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Nikolaou A, Salvador M, Wright I, Wantock T, Sandison G, Harle T, Carta D, Gutierrez-Merino J. The ratio of reactive oxygen and nitrogen species determines the type of cell death that bacteria undergo. Microbiol Res 2025; 292:127986. [PMID: 39675140 DOI: 10.1016/j.micres.2024.127986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2024] [Revised: 11/25/2024] [Accepted: 11/27/2024] [Indexed: 12/17/2024]
Abstract
Reactive oxygen and nitrogen species (RONS) are emerging as a novel antibacterial strategy to combat the alarming increase in antimicrobial resistance (AMR). RONS can inhibit bacterial growth through reactions with cellular molecules, compromising vital biological functions and leading to cell death. While their mechanisms of action have been studied, many remain unclear, especially in biologically relevant environments. In this study, we exposed Gram-positive and Gram-negative bacteria to varying RONS ratios, mimicking what microbes may naturally encounter. A ratio in favour of RNS induced membrane depolarization and pore formation, resulting in an irreversible bactericidal effect. By contrast, ROS predominance caused membrane permeabilization and necrotic-like responses, leading to biofilm formation. Furthermore, bacterial cells exposed to more RNS than ROS activated metabolic processes associated with anaerobic respiration, DNA & cell wall/membrane repair, and cell signalling. Our findings suggest that the combination of ROS and RNS can be an effective alternative to inhibit bacteria, but only under higher RNS levels, as ROS dominance might foster bacterial tolerance, which in the context of AMR could have devastating consequences.
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Affiliation(s)
- Athanasios Nikolaou
- School of Biosciences, University of Surrey, Guildford GU2 7XH, United Kingdom; School of Chemistry and Chemical Engineering, University of Surrey, Guildford G2 7XH, United Kingdom
| | - Manuel Salvador
- IDENER, Early Ovington 24-8, La Rinconada, Seville 41300, Spain
| | - Ian Wright
- School of Biosciences, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - Thomas Wantock
- Fourth State Medicine Ltd., Longfield, Fernhurst, Haslemere GU27 3HA, United Kingdom
| | - Gavin Sandison
- Fourth State Medicine Ltd., Longfield, Fernhurst, Haslemere GU27 3HA, United Kingdom
| | - Thomas Harle
- Fourth State Medicine Ltd., Longfield, Fernhurst, Haslemere GU27 3HA, United Kingdom
| | - Daniela Carta
- School of Chemistry and Chemical Engineering, University of Surrey, Guildford G2 7XH, United Kingdom
| | - Jorge Gutierrez-Merino
- School of Biosciences, University of Surrey, Guildford GU2 7XH, United Kingdom; School of Veterinary Medicine, University of Surrey, Guildford GU2 7AL, United Kingdom.
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2
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Wu KY, Yao FH, Ren XM, Hang XD, Bai YF, Qi SH. Multi-target anti-MRSA mechanism and antibiotic synergistic effect of marine alkaloid Ascomylactam A in vitro and in vivo against clinical MRSA strains. Biochem Pharmacol 2025; 232:116697. [PMID: 39643122 DOI: 10.1016/j.bcp.2024.116697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2024] [Revised: 11/26/2024] [Accepted: 12/03/2024] [Indexed: 12/09/2024]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA), as a kind of multi-drug resistant bacteria, often causes serious sanitary infection problems. Marine fungi are seen as a promising source of lead compounds for antibiotics. In this research, the antibacterial activity, antibiotic synergistic effect and mechanism of the alkaloid Ascomylactam A (AsA) derived from the marine fungus Microascus sp. SCSIO 41821 were investigated in vivo and in vitro. Antibacterial assays showed that AsA had excellent antibacterial activity and inhibition of biofilm formation against MRSA SC41993, and exhibitted synergistic antibacterial effects with clinical antibiotics. Transcriptomics revealed the potential mechanism that AsA affected the formation of MRSA biofilm, cell wall synthesis and virulence through LytSR, VraSR, ArgAC and KdpDE two-component system (TCS). In addition, by treatment with AsA, it was found that AdhE protein was a potential target for oxidative stress and lipid peroxidation in MRSA, and the resistance of MRSA was reversed by regulating some genes. In vivo experiments showed that AsA combined with gentamicin sulfate (GMS) had a better therapeutic effect than alone against clinical MRSA USA300, especially in the heart. In this study, the antibacterial mechanism of decahydrofluorene-class alkaloids was preliminarily investigated, supporting the potence of AsA as a promising therapeutic agent to combat MASA infections.
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Affiliation(s)
- Ke-Yue Wu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, Guangdong, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fei-Hua Yao
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, Guangdong, China
| | - Xu-Meng Ren
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, Guangdong, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xu-Dong Hang
- Department of Pathogen Biology, Jiangsu Key Laboratory of Pathogen Biology, Nanjing Medical University, Nanjing, China
| | - Yue-Fan Bai
- Department of Pathogen Biology, Jiangsu Key Laboratory of Pathogen Biology, Nanjing Medical University, Nanjing, China
| | - Shu-Hua Qi
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, Guangdong, China.
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3
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Hosmer J, McEwan AG, Kappler U. Bacterial acetate metabolism and its influence on human epithelia. Emerg Top Life Sci 2024; 8:1-13. [PMID: 36945843 PMCID: PMC10903459 DOI: 10.1042/etls20220092] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/16/2023] [Accepted: 03/02/2023] [Indexed: 03/23/2023]
Abstract
Short-chain fatty acids are known modulators of host-microbe interactions and can affect human health, inflammation, and outcomes of microbial infections. Acetate is the most abundant but least well-studied of these modulators, with most studies focusing on propionate and butyrate, which are considered to be more potent. In this mini-review, we summarize current knowledge of acetate as an important anti-inflammatory modulator of interactions between hosts and microorganisms. This includes a summary of the pathways by which acetate is metabolized by bacteria and human cells, the functions of acetate in bacterial cells, and the impact that microbially derived acetate has on human immune function.
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Affiliation(s)
- Jennifer Hosmer
- School of Chemistry and Molecular Biosciences, Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Australia
| | - Alastair G. McEwan
- School of Chemistry and Molecular Biosciences, Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Australia
| | - Ulrike Kappler
- School of Chemistry and Molecular Biosciences, Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Australia
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4
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Patel H, Rawat S. A genetic regulatory see-saw of biofilm and virulence in MRSA pathogenesis. Front Microbiol 2023; 14:1204428. [PMID: 37434702 PMCID: PMC10332168 DOI: 10.3389/fmicb.2023.1204428] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 05/30/2023] [Indexed: 07/13/2023] Open
Abstract
Staphylococcus aureus is one of the most common opportunistic human pathogens causing several infectious diseases. Ever since the emergence of the first methicillin-resistant Staphylococcus aureus (MRSA) strain decades back, the organism has been a major cause of hospital-acquired infections (HA-MRSA). The spread of this pathogen across the community led to the emergence of a more virulent subtype of the strain, i.e., Community acquired Methicillin resistant Staphylococcus aureus (CA-MRSA). Hence, WHO has declared Staphylococcus aureus as a high-priority pathogen. MRSA pathogenesis is remarkable because of the ability of this "superbug" to form robust biofilm both in vivo and in vitro by the formation of polysaccharide intercellular adhesin (PIA), extracellular DNA (eDNA), wall teichoic acids (WTAs), and capsule (CP), which are major components that impart stability to a biofilm. On the other hand, secretion of a diverse array of virulence factors such as hemolysins, leukotoxins, enterotoxins, and Protein A regulated by agr and sae two-component systems (TCS) aids in combating host immune response. The up- and downregulation of adhesion genes involved in biofilm formation and genes responsible for synthesizing virulence factors during different stages of infection act as a genetic regulatory see-saw in the pathogenesis of MRSA. This review provides insight into the evolution and pathogenesis of MRSA infections with a focus on genetic regulation of biofilm formation and virulence factors secretion.
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Affiliation(s)
| | - Seema Rawat
- Microbiology Laboratory, School of Life Sciences, Central University of Gujarat, Gandhinagar, Gujarat, India
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5
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Nguyen TQ, Heo BE, Park Y, Jeon S, Choudhary A, Moon C, Jang J. CRISPR Interference-Based Inhibition of MAB_0055c Expression Alters Drug Sensitivity in Mycobacterium abscessus. Microbiol Spectr 2023; 11:e0063123. [PMID: 37158736 PMCID: PMC10269454 DOI: 10.1128/spectrum.00631-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/21/2023] [Indexed: 05/10/2023] Open
Abstract
There is an unmet medical need for effective treatments against Mycobacterium abscessus infections. Although advanced molecular genetic tools to validate drug targets and resistance of M. abscessus exist, the practical design and construction of plasmids are relatively laborious and time-consuming. Thus, for this purpose, we used CRISPR interference (CRISPRi) combined with catalytically deactivated Cas9 to inhibit the gene expression of a predicted LysR-type transcriptional regulator gene, MAB_0055c, in M. abscessus and evaluated its contribution to the development of drug resistance. Our results showed that silencing the MAB_0055c gene lead to increased rifamycin susceptibility depending on the hydroquinone moiety. These results demonstrate that CRISPRi is an excellent approach for studying drug resistance in M. abscessus. IMPORTANCE In this study, we utilized CRISPR interference (CRISPRi) to specifically target the MAB_0055c gene in M. abscessus, a bacterium that causes difficult-to-treat infections. The study found that silencing the gene lead to increased rifabutin and rifalazil susceptibility. This study is the first to establish a link between the predicted LysR-type transcriptional regulator gene and antibiotic resistance in mycobacteria. These findings underscore the potential of using CRISPRi as a tool for elucidating resistance mechanisms, essential drug targets, and drug mechanisms of action, which could pave the way for more effective treatments for M. abscessus infections. The results of this study could have important implications for the development of new therapeutic options for this challenging-to-treat bacterial infection.
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Affiliation(s)
- Thanh Quang Nguyen
- Division of Life Science, Department of Bio & Medical Big Data (BK21 Four Program), Research Institute of Life Science, Gyeongsang National University, Jinju, Republic of Korea
| | - Bo Eun Heo
- Division of Life Science, Department of Bio & Medical Big Data (BK21 Four Program), Research Institute of Life Science, Gyeongsang National University, Jinju, Republic of Korea
| | - Yujin Park
- Division of Life Science, Department of Bio & Medical Big Data (BK21 Four Program), Research Institute of Life Science, Gyeongsang National University, Jinju, Republic of Korea
| | - Seunghyeon Jeon
- Division of Life Science, Department of Bio & Medical Big Data (BK21 Four Program), Research Institute of Life Science, Gyeongsang National University, Jinju, Republic of Korea
| | - Arunima Choudhary
- Division of Life Science, Department of Bio & Medical Big Data (BK21 Four Program), Research Institute of Life Science, Gyeongsang National University, Jinju, Republic of Korea
| | - Cheol Moon
- Department of Clinical Laboratory Science, Semyung University, Jecheon, Republic of Korea
| | - Jichan Jang
- Division of Life Science, Department of Bio & Medical Big Data (BK21 Four Program), Research Institute of Life Science, Gyeongsang National University, Jinju, Republic of Korea
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Tyagi E, Singhvi N, Keshavam CC, Sangwan N, Gupta V, Bhimwal T, Seth R, Seth RK, Singh Y. Phylogenetic analysis and interactomics study unveil gene co-optive evolution of LysR-type transcription regulators across non-pathogenic, opportunistic, and pathogenic mycobacteria. 3 Biotech 2023; 13:168. [PMID: 37188288 PMCID: PMC10167064 DOI: 10.1007/s13205-023-03583-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/23/2023] [Indexed: 05/17/2023] Open
Abstract
Mycobacterial species is known for inhabiting various niches ranging from soil to harsh intracellular environment of animal hosts and their survival through constant changes. For survival and persistence, these organisms must quickly adapt by bringing shift in their metabolism. Metabolic shifts are brought by sensing the environmental cues usually by membrane localized sensor molecules. These signals are transmitted to regulators of various metabolic pathways leading to post-translational modifications of regulators ultimately resulting in altered metabolic state of the cell. Multiple regulatory mechanisms have been unearthed so far that play crucial role in adapting to these situations, and among them, the signal-dependent transcriptional regulators mediated responses are integral for the microbes to perceive environmental signals and generate appropriate adaptive responses. LysR-type transcriptional regulators (LTTRs) form the largest family of transcriptional regulators, which are present in all kingdoms of life. Their numbers vary among bacterial genera and even in different mycobacterial species. To understand the evolutionary aspect of pathogenicity based on LTTRs, we performed phylogenetic analysis of LTTRs encoded by several mycobacterial species representing non-pathogenic (NP), opportunistic (OP), and totally pathogenic (TP) mycobacteria. Our results showed that LTTRs of TP clustered separately from LTTRs of NP and OP mycobacteria. In addition, LTTRs frequency per Mb of genome was reduced in TP when compared with NP and OP. Further, the protein-protein interactions and degree-based network analysis showed concomitant increased interactions per LTTRs with increase in pathogenicity. These results suggested the increase in regulon of LTTRs during evolution of TP mycobacteria.
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Affiliation(s)
- Ekta Tyagi
- Department of Zoology, University of Delhi, Delhi, 110007 India
| | - Nirjara Singhvi
- School of Allied Sciences, Dev Bhoomi Uttarakhand University, Dehradun, Uttarakhand 248001 India
| | | | - Nitika Sangwan
- Department of Zoology, University of Delhi, Delhi, 110007 India
| | - Vipin Gupta
- Ministry of Environment Forest & Climate Change, Integrated Regional Office, Dehradun, 248001 India
| | - Tanisha Bhimwal
- Department of Zoology, University of Delhi, Delhi, 110007 India
| | - Ranjana Seth
- Deshbandhu College, University of Delhi South Campus, New Delhi, 110019 India
| | | | - Yogendra Singh
- Department of Zoology, University of Delhi, Delhi, 110007 India
- Present Address: Delhi School of Public Health, Institution of Eminence, University of Delhi, Delhi, 110007 India
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7
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Sousa FM, Fernandes B, Pereira MM. The protein family of pyruvate:quinone oxidoreductases: Amino acid sequence conservation and taxonomic distribution. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148958. [PMID: 36758662 DOI: 10.1016/j.bbabio.2023.148958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 12/24/2022] [Accepted: 02/01/2023] [Indexed: 02/11/2023]
Abstract
Pyruvate:quinone oxidoreductases (PQOs) catalyse the oxidative decarboxylation of pyruvate to acetate and concomitant reduction of quinone to quinol with the release of CO2. They are thiamine pyrophosphate (TPP) and flavin-adenine dinucleotide (FAD) containing enzymes, which interact with the membrane in a monotopic way. PQOs are considered as part of alternatives to most recognized pyruvate catabolizing pathways, and little is known about their taxonomic distribution and structural/functional relationship. In this bioinformatics work we tackled these gaps in PQO knowledge. We used the KEGG database to identify PQO coding genes, performed a multiple sequence analysis which allowed us to study the amino acid conservation on these enzymes, and looked at their possible cellular function. We observed that PQOS are enzymes exclusively present in prokaryotes with most of the sequences identified in bacteria. Regarding the amino acid sequence conservation, we found that 75 amino acid residues (out of 570, on average) have a conservation over 90 %, and that the most conserved regions in the protein are observed around the TPP and FAD binding sites. We systematized the presence of conserved features involved in Mg2+, TPP and FAD binding, as well as residues directly linked to the catalytic mechanism. We also established the presence of a new motif named "HEH lock", possibly involved in the dimerization process. The results here obtained for the PQO protein family contribute to a better understanding of the biochemistry of these respiratory enzymes.
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Affiliation(s)
- Filipe M Sousa
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal; BioISI-Biosystems & Integrative Sciences Institute and Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa, 1749-016 Lisboa, Portugal
| | - Bárbara Fernandes
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal; BioISI-Biosystems & Integrative Sciences Institute and Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa, 1749-016 Lisboa, Portugal
| | - Manuela M Pereira
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal; BioISI-Biosystems & Integrative Sciences Institute and Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa, 1749-016 Lisboa, Portugal.
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8
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He X, Zhang W, Cao Q, Li Y, Bao G, Lin T, Bao J, Chang C, Yang C, Yin Y, Xu J, Ren Z, Jin Y, Lu F. Global Downregulation of Penicillin Resistance and Biofilm Formation by MRSA Is Associated with the Interaction between Kaempferol Rhamnosides and Quercetin. Microbiol Spectr 2022; 10:e0278222. [PMID: 36354319 PMCID: PMC9769653 DOI: 10.1128/spectrum.02782-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 10/24/2022] [Indexed: 11/12/2022] Open
Abstract
The rapid development of methicillin-resistant Staphylococcus aureus (MRSA) drug resistance and the formation of biofilms seriously challenge the clinical application of classic antibiotics. Extracts of the traditional herb Chenopodium ambrosioides L. were found to have strong antibiofilm activity against MRSA, but their mechanism of action remains poorly understood. This study was designed to investigate the antibacterial and antibiofilm activities against MRSA of flavonoids identified from C. ambrosioides L. in combination with classic antibiotics, including ceftazidime, erythromycin, levofloxacin, penicillin G, and vancomycin. Liquid chromatography-mass spectrometry (LC-MS) was used to analyze the nonvolatile chemical compositions. Reverse transcription (RT)-PCR was used to investigate potential multitargets of flavonoids based on global transcriptional responses of virulence and antibiotic resistance. A synergistic antibacterial and biofilm-inhibiting activity of the alcoholic extract of the ear of C. ambrosioides L. in combination with penicillin G was observed against MRSA, which proved to be closely related to the interaction of the main components of kaempferol rhamnosides with quercetin. In regard to the mechanism, the increased sensitivity of MRSA to penicillin G was shown to be related to the downregulation of penicillinase with SarA as a potential drug target, while the antibiofilm activity was mainly related to downregulation of various virulence factors involved in the initial and mature stages of biofilm development, with SarA and/or σB as drug targets. This study provides a theoretical basis for further exploration of the medicinal activity of kaempferol rhamnosides and quercetin and their application in combination with penicillin G against MRSA biofilm infection. IMPORTANCE In this study, the synergistic antibacterial and antibiofilm effects of the traditional herb C. ambrosioides L. and the classic antibiotic penicillin G on MRSA provide a potential strategy to deal with the rapid development of MRSA antibiotic resistance. This study also provides a theoretical basis for further optimizing the combined effect of kaempferol rhamnosides, quercetin, and penicillin G and exploring anti-MRSA biofilm infection research with SarA and σB as drug targets.
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Affiliation(s)
- Xinlong He
- Department of Pathogenic Biology, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
- Affiliated Hospital of Yangzhou University, Yangzhou, People’s Republic of China
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, People’s Republic of China
- Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, People’s Republic of China
| | - Wenwen Zhang
- Department of Pathogenic Biology, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
| | - Qingchao Cao
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, People’s Republic of China
| | - Yinyue Li
- Department of Pathogenic Biology, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
| | - Guangyu Bao
- Affiliated Hospital of Yangzhou University, Yangzhou, People’s Republic of China
| | - Tao Lin
- Affiliated Hospital of Yangzhou University, Yangzhou, People’s Republic of China
| | - Jiaojiao Bao
- Affiliated Hospital of Yangzhou University, Yangzhou, People’s Republic of China
| | - Caiwang Chang
- Affiliated Hospital of Yangzhou University, Yangzhou, People’s Republic of China
| | - Changshui Yang
- Department of Pharmacy, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
| | - Yi Yin
- Department of Pathogenic Biology, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
| | - Jiahui Xu
- Department of Pathogenic Biology, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
| | - Zhenyu Ren
- Department of Pathogenic Biology, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
| | - Yingshan Jin
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, People’s Republic of China
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, People’s Republic of China
| | - Feng Lu
- Department of Pathogenic Biology, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
- Affiliated Hospital of Yangzhou University, Yangzhou, People’s Republic of China
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, People’s Republic of China
- Jiangsu Key Laboratory of Experimental & Translational Non-coding RNA Research, School of Medicine, Yangzhou University, Yangzhou, People’s Republic of China
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, People’s Republic of China
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Chang AW, Dowd SE, Brackee G, Fralick JA, Vediyappan G. Inhibition of Staphylococcus aureus biofilm formation by gurmarin, a plant-derived cyclic peptide. Front Cell Infect Microbiol 2022; 12:1017545. [PMID: 36268224 PMCID: PMC9578378 DOI: 10.3389/fcimb.2022.1017545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/13/2022] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus (Sa) is an opportunistic pathogen capable of causing various infections ranging from superficial skin infections to life-threatening severe diseases including pneumonia and sepsis. Sa produces biofilms readily on biotic and abiotic surfaces. Biofilm cells are embedded in a protective polysaccharide matrix and show an innate resistance to antibiotics, disinfectants, and clearance by host defenses. Additionally, biofilms serve as a source for systemic dissemination. Moreover, infections associated with biofilms may result in longer hospitalizations, a need for surgery, and may even result in death. Agents that inhibit the formation of biofilms and virulence without affecting bacterial growth to avoid the development of drug resistance could be useful for therapeutic purposes. In this regard, we identified and purified a small cyclic peptide, gurmarin, from a plant source that inhibited the formation of Sa biofilm under in vitro growth conditions without affecting the viability of the bacterium. The purified peptide showed a predicted molecular size of ~4.2 kDa on SDS-PAGE. Transcriptomic analysis of Sa biofilm treated with peptide showed 161 differentially affected genes at a 2-fold change, and some of them include upregulation of genes involved in oxidoreductases and downregulation of genes involved in transferases and hydrolases. To determine the inhibitory effect of the peptide against Sa biofilm formation and virulence in vivo, we used a rat-implant biofilm model. Sa infected implants with or without peptide were placed under the neck skin of rats for seven days. Implants treated with peptide showed a reduction of CFU and lack of edema and sepsis when compared to that of control animals without peptide. Taken together, gurmarin peptide blocks Sa biofilm formation in vitro and in vivo and can be further developed for therapeutic use.
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Affiliation(s)
- Adeline W. Chang
- Division of Biology, Kansas State University, Manhattan, KS, United States
| | - Scot E. Dowd
- MR DNA (Molecular Research), Shallowater, TX, United States
| | - Gordon Brackee
- Laboratory Animal Resources Center, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Joe A. Fralick
- Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Govindsamy Vediyappan
- Division of Biology, Kansas State University, Manhattan, KS, United States
- Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- *Correspondence: Govindsamy Vediyappan,
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10
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Interactions between Jumbo Phage SA1 and Staphylococcus: A Global Transcriptomic Analysis. Microorganisms 2022; 10:microorganisms10081590. [PMID: 36014008 PMCID: PMC9414953 DOI: 10.3390/microorganisms10081590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 07/30/2022] [Accepted: 08/02/2022] [Indexed: 01/21/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is an important zoonotic pathogen that poses a serious health concern to humans and cattle worldwide. Although it has been proven that lytic phages may successfully kill S. aureus, the interaction between the host and the phage has yet to be thoroughly investigated, which will likely limit the clinical application of phage. Here, RNA sequencing (RNA-seq) was used to examine the transcriptomics of jumbo phage SA1 and Staphylococcus JTB1-3 during a high multiplicity of infection (MOI) and RT-qPCR was used to confirm the results. The RNA-seq analysis revealed that phage SA1 took over the transcriptional resources of the host cells and that the genes were categorized as early, middle, and late, based on the expression levels during infection. A minor portion of the resources of the host was employed to enable phage replication after infection because only 35.73% (997/2790) of the host genes were identified as differentially expressed genes (DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that the phage infection mainly affected the nucleotide metabolism, protein metabolism, and energy-related metabolism of the host. Moreover, the expression of the host genes involved in anti-phage systems, virulence, and drug resistance significantly changed during infection. This research gives a fresh understanding of the relationship between jumbo phages and their Gram-positive bacteria hosts and provides a reference for studying phage treatment and antibiotics.
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Abstract
What do programmed cell death (PCD) and carbohydrate metabolism by-product transport have in common? Intriguingly, both processes involve the cidABC and lrgAB operons in the major human pathogen Staphylococcus aureus. Previously, CidA and LrgA have been studied in the context of programmed cell death, but a second function in overflow metabolism is increasingly evident. New work from J. L. Endres, S. S. Chaudhari, X. Zhang, J. Prahlad, et al. (mBio 13:e02827-21, 2022, https://doi.org/10.1128/mBio.02827-21) combining a lysis cassette, mutagenesis, and classic microbiology demonstrates that CidA and LrgA function as holins to support endolysin-induced lysis. But that's not all-the lrgAB operon also facilitates pyruvate uptake during microaerobic and anaerobic growth. This commentary highlights the main findings from this work and places them in context of the literature to date. Finally, as these proteins are highly conserved and carry out disparate functions of great importance, it is tempting to speculate future work will elucidate the link between S. aureus lysis and pyruvate metabolism.
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G C B, Sahukhal GS, Elasri MO. Delineating the Role of the msaABCR Operon in Staphylococcal Overflow Metabolism. Front Microbiol 2022; 13:914512. [PMID: 35722290 PMCID: PMC9204165 DOI: 10.3389/fmicb.2022.914512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus is an important human pathogen that can infect almost every organ system, resulting in a high incidence of morbidity and mortality. The msaABCR operon is an important regulator of several staphylococcal phenotypes, including biofilm development, cell wall crosslinking, antibiotic resistance, oxidative stress, and acute and chronic implant-associated osteomyelitis. Our previous study showed that, by modulating murein hydrolase activity, the msaABCR operon negatively regulates the proteases that govern cell death. Here, we report further elucidation of the mechanism of cell death, which is regulated by the msaABCR operon at the molecular level in the USA300 LAC strain. We showed that deletion of msaABCR enhances weak-acid-dependent cell death, because, in the biofilm microenvironment, this mutant strain consumes glucose and produces acetate and acetoin at higher rates than wild-type USA300 LAC strain. We proposed the increased intracellular acidification leads to increased cell death. MsaB, a dual-function transcription factor and RNA chaperone, is a negative regulator of the cidR regulon, which has been shown to play an important role in overflow metabolism and programmed cell death during biofilm development in S. aureus. We found that MsaB binds directly to the cidR promoter, which represses expression of the cidR regulon and prevents transcription of the cidABC and alsSD operons. In addition, we observed that pyruvate induced expression of the msaABCR operon (MsaB). The results reported here have enabled us to decipher the role of the msaABCR operon in staphylococcal metabolic adaption during biofilm development.
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Affiliation(s)
- Bibek G C
- Center for Molecular and Cellular Biosciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Gyan S. Sahukhal
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
- *Correspondence: Gyan S. Sahukhal,
| | - Mohamed O. Elasri
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
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13
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Cordero M, García-Fernández J, Acosta IC, Yepes A, Avendano-Ortiz J, Lisowski C, Oesterreicht B, Ohlsen K, Lopez-Collazo E, Förstner KU, Eulalio A, Lopez D. The induction of natural competence adapts staphylococcal metabolism to infection. Nat Commun 2022; 13:1525. [PMID: 35314690 PMCID: PMC8938553 DOI: 10.1038/s41467-022-29206-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 03/03/2022] [Indexed: 11/26/2022] Open
Abstract
A central question concerning natural competence is why orthologs of competence genes are conserved in non-competent bacterial species, suggesting they have a role other than in transformation. Here we show that competence induction in the human pathogen Staphylococcus aureus occurs in response to ROS and host defenses that compromise bacterial respiration during infection. Bacteria cope with reduced respiration by obtaining energy through fermentation instead. Since fermentation is energetically less efficient than respiration, the energy supply must be assured by increasing the glycolytic flux. The induction of natural competence increases the rate of glycolysis in bacteria that are unable to respire via upregulation of DNA- and glucose-uptake systems. A competent-defective mutant showed no such increase in glycolysis, which negatively affects its survival in both mouse and Galleria infection models. Natural competence foster genetic variability and provides S. aureus with additional nutritional and metabolic possibilities, allowing it to proliferate during infection.
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Affiliation(s)
- Mar Cordero
- National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), 28049, Madrid, Spain
| | - Julia García-Fernández
- National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), 28049, Madrid, Spain
| | - Ivan C Acosta
- National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), 28049, Madrid, Spain
| | - Ana Yepes
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, 97080, Würzburg, Germany
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, 97080, Würzburg, Germany
| | - Jose Avendano-Ortiz
- The Innate Immune Response and Tumor Immunology Group, IdiPaz La Paz University Hospital, 28046, Madrid, Spain
| | - Clivia Lisowski
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, 97080, Würzburg, Germany
| | - Babett Oesterreicht
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, 97080, Würzburg, Germany
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, 97080, Würzburg, Germany
| | - Knut Ohlsen
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, 97080, Würzburg, Germany
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, 97080, Würzburg, Germany
| | - Eduardo Lopez-Collazo
- The Innate Immune Response and Tumor Immunology Group, IdiPaz La Paz University Hospital, 28046, Madrid, Spain
- CIBER of Respiratory Diseases (CIBERES), Madrid, Spain
| | - Konrad U Förstner
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, 97080, Würzburg, Germany
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, 97080, Würzburg, Germany
- Information Centre for Life Science (ZBMED), 50931, Cologne, Germany
- TH Köln - University of Applied Sciences, 50578, Cologne, Germany
| | - Ana Eulalio
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, 97080, Würzburg, Germany
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504, Coimbra, Portugal
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Daniel Lopez
- National Centre for Biotechnology, Spanish National Research Council (CNB-CSIC), 28049, Madrid, Spain.
- Research Centre for Infectious Diseases (ZINF), University of Würzburg, 97080, Würzburg, Germany.
- Institute for Molecular Infection Biology (IMIB), University of Würzburg, 97080, Würzburg, Germany.
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14
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Islam MM, Kim K, Lee JC, Shin M. LeuO, a LysR-Type Transcriptional Regulator, Is Involved in Biofilm Formation and Virulence of Acinetobacter baumannii. Front Cell Infect Microbiol 2021; 11:738706. [PMID: 34708004 PMCID: PMC8543017 DOI: 10.3389/fcimb.2021.738706] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/23/2021] [Indexed: 12/05/2022] Open
Abstract
Acinetobacter baumannii is an important nosocomial pathogen that can survive in different environmental conditions and poses a severe threat to public health due to its multidrug resistance properties. Research on transcriptional regulators, which play an essential role in adjusting to new environments, could provide new insights into A. baumannii pathogenesis. LysR-type transcriptional regulators (LTTRs) are structurally conserved among bacterial species and regulate virulence in many pathogens. We identified a novel LTTR, designated as LeuO encoded in the A. baumannii genome. After construction of LeuO mutant strain, transcriptome analysis showed that LeuO regulates the expression of 194 upregulated genes and 108 downregulated genes responsible for various functions and our qPCR validation of several differentially expressed genes support transcriptome data. Our results demonstrated that disruption of LeuO led to increased biofilm formation and increased pathogenicity in an animal model. However, the adherence and surface motility of the LeuO mutant were reduced compared with those of the wild-type strain. We observed some mutations on amino acids sequence of LeuO in clinical isolates. These mutations in the A. baumannii biofilm regulator LeuO may cause hyper-biofilm in the tested clinical isolates. This study is the first to demonstrate the association between the LTTR member LeuO and virulence traits of A. baumannii.
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Affiliation(s)
- Md Maidul Islam
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Kyeongmin Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Je Chul Lee
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Minsang Shin
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
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15
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Felden B, Augagneur Y. Diversity and Versatility in Small RNA-Mediated Regulation in Bacterial Pathogens. Front Microbiol 2021; 12:719977. [PMID: 34447363 PMCID: PMC8383071 DOI: 10.3389/fmicb.2021.719977] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 07/20/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial gene expression is under the control of a large set of molecules acting at multiple levels. In addition to the transcription factors (TFs) already known to be involved in global regulation of gene expression, small regulatory RNAs (sRNAs) are emerging as major players in gene regulatory networks, where they allow environmental adaptation and fitness. Developments in high-throughput screening have enabled their detection in the entire bacterial kingdom. These sRNAs influence a plethora of biological processes, including but not limited to outer membrane synthesis, metabolism, TF regulation, transcription termination, virulence, and antibiotic resistance and persistence. Almost always noncoding, they regulate target genes at the post-transcriptional level, usually through base-pair interactions with mRNAs, alone or with the help of dedicated chaperones. There is growing evidence that sRNA-mediated mechanisms of actions are far more diverse than initially thought, and that they go beyond the so-called cis- and trans-encoded classifications. These molecules can be derived and processed from 5' untranslated regions (UTRs), coding or non-coding sequences, and even from 3' UTRs. They usually act within the bacterial cytoplasm, but recent studies showed sRNAs in extracellular vesicles, where they influence host cell interactions. In this review, we highlight the various functions of sRNAs in bacterial pathogens, and focus on the increasing examples of widely diverse regulatory mechanisms that might compel us to reconsider what constitute the sRNA.
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Affiliation(s)
- Brice Felden
- Inserm, Bacterial Regulatory RNAs and Medicine (BRM) - UMR_S 1230, Rennes, France
| | - Yoann Augagneur
- Inserm, Bacterial Regulatory RNAs and Medicine (BRM) - UMR_S 1230, Rennes, France
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16
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Anaerobic Microbiota Derived from the Upper Airways Impact Staphylococcus aureus Physiology. Infect Immun 2021; 89:e0015321. [PMID: 34125598 DOI: 10.1128/iai.00153-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Staphylococcus aureus is associated with the development of persistent and severe inflammatory diseases of the upper airways. Yet, S. aureus is also carried asymptomatically in the sinonasal cavity of ∼50% of healthy adults. The causes of this duality and host and microbial factors that tip the balance between S. aureus pathogenesis and commensalism are poorly understood. We have shown that by degrading mucins, anaerobic microbiota support the growth of airway pathogens by liberating metabolites that are otherwise unavailable. Given the widely reported culture-based detection of anaerobes from individuals with chronic rhinosinusitis (CRS), here we tested our hypothesis that CRS microbiota is characterized by a mucin-degrading phenotype that alters S. aureus physiology. Using 16S rRNA gene sequencing, we indeed observed an increased prevalence and abundance of anaerobes in CRS relative to non-CRS controls. PICRUSt2-based functional predictions suggested increased mucin degradation potential among CRS microbiota that was confirmed by direct enrichment culture. Prevotella, Fusobacterium, and Streptococcus comprised a core mucin-degrading community across CRS subjects that generated a nutrient pool that augmented S. aureus growth on mucin as a carbon source. Finally, using transcriptome sequencing (RNA-seq), we observed that S. aureus transcription is profoundly altered in the presence of mucin-derived metabolites, though expression of several key metabolism- and virulence-associated pathways varied between CRS-derived bacterial communities. Together, these data support a model in which S. aureus metabolism and virulence in the upper airways are dependent upon the composition of cocolonizing microbiota and the metabolites they exchange.
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17
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Liu J, Shen Z, Tang J, Huang Q, Jian Y, Liu Y, Wang Y, Ma X, Liu Q, He L, Li M. Extracellular DNA released by glycine-auxotrophic Staphylococcus epidermidis small colony variant facilitates catheter-related infections. Commun Biol 2021; 4:904. [PMID: 34294851 PMCID: PMC8298460 DOI: 10.1038/s42003-021-02423-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/05/2021] [Indexed: 11/09/2022] Open
Abstract
Though a definitive link between small colony variants (SCVs) and implant-related staphylococcal infections has been well-established, the specific underlying mechanism remains an ill-explored field. The present study analyzes the role SCVs play in catheter infection by performing genomic and metabolic analyses, as well as analyzing biofilm formation and impacts of glycine on growth and peptidoglycan-linking rate, on a clinically typical Staphylococcus epidermidis case harboring stable SCV, normal counterpart (NC) and nonstable SCV. Our findings reveal that S. epidermidis stable SCV carries mutations involved in various metabolic processes. Metabolome analyses demonstrate that two biosynthetic pathways are apparently disturbed in SCV. One is glycine biosynthesis, which contributes to remarkable glycine shortage, and supplementation of glycine restores growth and peptidoglycan-linking rate of SCV. The other is overflow of pyruvic acid and acetyl-CoA, leading to excessive acetate. SCV demonstrates higher biofilm-forming ability due to rapid autolysis and subsequent eDNA release. Despite a remarkable decline in cell viability, SCV can facilitate in vitro biofilm formation and in vivo survival of NC when co-infected with its normal counterparts. This work illustrates an intriguing strategy utilized by a glycine-auxotrophic clinical S. epidermidis SCV isolate to facilitate biofilm-related infections, and casts a new light on the role of SCV in persistent infections.
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Affiliation(s)
- Junlan Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Zhen Shen
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Jin Tang
- Department of Laboratory Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Qian Huang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Ying Jian
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Yao Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Yanan Wang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Xiaowei Ma
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Qian Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Lei He
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.
| | - Min Li
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China. .,Faculty of Medical Laboratory Science, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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18
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The Staphylococcus aureus CidA and LrgA Proteins Are Functional Holins Involved in the Transport of By-Products of Carbohydrate Metabolism. mBio 2021; 13:e0282721. [PMID: 35100878 PMCID: PMC8805020 DOI: 10.1128/mbio.02827-21] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The Staphylococcus aureus cidABC and lrgAB operons encode members of a well-conserved family of proteins thought to be involved in programmed cell death (PCD). Based on the structural similarities that CidA and LrgA share with bacteriophage holins, we have hypothesized that these proteins function by forming pores within the cytoplasmic membrane. To test this, we utilized a "lysis cassette" system that demonstrated the abilities of the cidA and lrgA genes to support bacteriophage endolysin-induced cell lysis. Typical of holins, CidA- and LrgA-induced lysis was dependent on the coexpression of endolysin, consistent with the proposed holin-like functions of these proteins. In addition, the CidA and LrgA proteins were shown to localize to the surface of membrane vesicles and cause leakage of small molecules, providing direct evidence of their hole-forming potential. Consistent with recent reports demonstrating a role for the lrgAB homologues in other bacterial and plant species in the transport of by-products of carbohydrate metabolism, we also show that lrgAB is important for S. aureus to utilize pyruvate during microaerobic and anaerobic growth, by promoting the uptake of pyruvate under these conditions. Combined, these data reveal that the CidA and LrgA membrane proteins possess holin-like properties that play an important role in the transport of small by-products of carbohydrate metabolism. IMPORTANCE The Staphylococcus aureus cidABC and lrgAB operons represent the founding members of a large, highly conserved family of genes that span multiple kingdoms of life. Despite the fact that they have been shown to be involved in bacterial PCD, very little is known about the molecular/biochemical functions of the proteins they encode. The results presented in this study reveal that the cidA and lrgA genes encode proteins with bacteriophage holin-like functions, consistent with their roles in cell death. However, these studies also demonstrate that these operons are involved in the transport of small metabolic by-products of carbohydrate metabolism, suggesting an intriguing link between these two seemingly disparate processes.
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19
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Novel Functions and Signaling Specificity for the GraS Sensor Kinase of Staphylococcus aureus in Response to Acidic pH. J Bacteriol 2020; 202:JB.00219-20. [PMID: 32868405 DOI: 10.1128/jb.00219-20] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 08/26/2020] [Indexed: 01/30/2023] Open
Abstract
Although the GraS sensor kinase of Staphylococcus aureus is known for the sensing of and resistance to cationic antimicrobial peptides (CAMPs), we recently established that it also signals in response to acidic pH, which is encountered on human skin concurrently with CAMPs, antimicrobial unsaturated free fatty acids (uFFA), and calcium. We therefore evaluated how these environmental signals would affect GraS function and resistance to antimicrobial uFFA. Growth at pH 5.5 promoted increased resistance of S. aureus USA300 to linoleic and arachidonic acids but not palmitoleic or sapienic acid. However, enhanced resistance to these C16:1 uFFA was achieved by supplementing acidic medium with 0.5 mM calcium or subinhibitory CAMPs. Enhanced resistance to uFFA at acidic pH was dependent on GraS and GraS-dependent expression of the lysyl-phosphatidylglycerol synthase enzyme MprF, through a mechanism that did not require the lysyl-transferase function of MprF. In addition to enhanced resistance to antimicrobial uFFA, acidic pH also promoted increased production of secreted proteases in a GraS-dependent manner. During growth at pH 5.5, downstream phenotypes of signaling through GraS, including resistance to uFFA, MprF-dependent addition of positive charge to the cell surface, and increased production of secreted proteases, all occurred independently of acidic amino acids in the extracytoplasmic sensor loop of GraS that were previously found to be required for sensing of CAMPs. Cumulatively, our data indicate that signaling through GraS at acidic pH occurs through a mechanism that is distinct from that described for CAMPs, leading to increased resistance to antimicrobial uFFA and production of secreted proteases.IMPORTANCE Staphylococcus aureus asymptomatically colonizes 30% of humans but is also a leading cause of infectious morbidity and mortality. Since infections are typically initiated by the same strain associated with asymptomatic colonization of the nose or skin, it is important to understand how the microbe can endure exposure to harsh conditions that successfully restrict the growth of other bacteria, including a combination of acidic pH, antimicrobial peptides, and antimicrobial fatty acids. The significance of our research is in showing that acidic pH combined with antimicrobial peptide or environmental calcium can signal through a single membrane sensor protein to promote traits that may aid in survival, including modification of cell surface properties, increased resistance to antimicrobial fatty acids, and enhanced production of secreted proteases.
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20
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Butina K, Tomac A, Choong FX, Shirani H, Nilsson KPR, Löffler S, Richter-Dahlfors A. Optotracing for selective fluorescence-based detection, visualization and quantification of live S. aureus in real-time. NPJ Biofilms Microbiomes 2020; 6:35. [PMID: 33037198 PMCID: PMC7547713 DOI: 10.1038/s41522-020-00150-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 09/10/2020] [Indexed: 11/09/2022] Open
Abstract
Methods for bacterial detection are needed to advance the infection research and diagnostics. Based on conformation-sensitive fluorescent tracer molecules, optotracing was recently established for dynamic detection and visualization of structural amyloids and polysaccharides in the biofilm matrix of gram-negative bacteria. Here, we extend the use of optotracing for detection of gram-positive bacteria, focussing on the clinically relevant opportunistic human pathogen Staphylococcus aureus. We identify a donor-acceptor-donor-type optotracer, whose binding-induced fluorescence enables real-time detection, quantification, and visualization of S. aureus in monoculture and when mixed with gram-negative Salmonella Enteritidis. An algorithm-based automated high-throughput screen of 1920 S. aureus transposon mutants recognized the cell envelope as the binding target, which was corroborated by super-resolution microscopy of bacterial cells and spectroscopic analysis of purified cell wall components. The binding event was essentially governed by hydrophobic interactions, which permitted custom-designed tuning of the binding selectivity towards S. aureus versus Enterococcus faecalis by appropriate selection of buffer conditions. Collectively this work demonstrates optotracing as an enabling technology relevant for any field of basic and applied research, where visualization and detection of S. aureus is needed.
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Affiliation(s)
- Karen Butina
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Ana Tomac
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Ferdinand X Choong
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Hamid Shirani
- Department of Chemistry, IFM, Linköping University, SE-581 83, Linköping, Sweden
| | - K Peter R Nilsson
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Chemistry, IFM, Linköping University, SE-581 83, Linköping, Sweden
| | - Susanne Löffler
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden.,Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Agneta Richter-Dahlfors
- AIMES-Center for the Advancement of Integrated Medical and Engineering Sciences at Karolinska Institutet and KTH Royal Institute of Technology, Stockholm, Sweden. .,Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden.
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21
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Fu Y, Zhang L, Wang G, Lin Y, Ramanathan S, Yang G, Lin W, Lin X. The LysR-Type Transcriptional Regulator YeeY Plays Important Roles in the Regulatory of Furazolidone Resistance in Aeromonas hydrophila. Front Microbiol 2020; 11:577376. [PMID: 33013815 PMCID: PMC7509050 DOI: 10.3389/fmicb.2020.577376] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 08/19/2020] [Indexed: 12/18/2022] Open
Abstract
Aeromonas hydrophila is an aquatic pathogen of freshwater fish. The emergence of widespread antimicrobial-resistance strains of this pathogen has caused increasing rates of fish infections. Our previous research reported that A. hydrophila yeeY, a LysR-type transcriptional regulator (LTTR), negatively regulated furazolidone (FZ) resistance. Although, it’s intrinsic regulatory mechanism is still unclear. In this study, a data-independent acquisition (DIA) quantitative proteomics method was used to compare the differentially expressed proteins (DEPs) between the ΔyeeY and wild-type strain under FZ treatment. When compared to the control, a total of 594 DEPs were identified in ΔyeeY. Among which, 293 and 301 proteins were substantially increased and decreased in abundance, respectively. Bioinformatics analysis showed that several biological pathways such as the secretion system and protein transport were mainly involved in FZ resistance. Subsequently, the antibiotics susceptibility assays of several gene deletion strains identified from the proteomics results showed that YeeY may regulate some important genes such as cysD, AHA_2766, AHA_3195, and AHA_4275, which affects the FZ resistance in A. hydrophila. Furthermore, 34 antimicrobial resistance genes (ARGs) from the bacterial drug resistance gene database (CARD) were found to be directly or indirectly regulated by YeeY. A subsequent assay of several ARGs mutants showed that ΔAHA_3222 increased the susceptibility of A. hydrophila to FZ, while ΔcysN and ΔAHA_3753 decreased the susceptibility rate. Finally, the chromatin immunoprecipitation (ChIP) PCR and an electrophoretic mobility shift assay (EMSA) have revealed that the genes such as AHA_3222 and AHA_4275 were directly and transcriptionally regulated by YeeY. Taken together, our findings demonstrated that YeeY may participate in antimicrobial resistance of A. hydrophila to FZ, which provides a new target for the development of novel antimicrobial agents in the future.
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Affiliation(s)
- Yuying Fu
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fuzhou, China
| | - Lishan Zhang
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fuzhou, China
| | - Guibin Wang
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fuzhou, China.,State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing, China
| | - Yuexu Lin
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fuzhou, China
| | - Srinivasan Ramanathan
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fuzhou, China
| | - Guidi Yang
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fuzhou, China
| | - Wenxiong Lin
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fuzhou, China
| | - Xiangmin Lin
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fuzhou, China.,Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, China
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22
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Presentato A, Piacenza E, Scurria A, Albanese L, Zabini F, Meneguzzo F, Nuzzo D, Pagliaro M, Martino DC, Alduina R, Ciriminna R. A New Water-Soluble Bactericidal Agent for the Treatment of Infections Caused by Gram-Positive and Gram-Negative Bacterial Strains. Antibiotics (Basel) 2020; 9:antibiotics9090586. [PMID: 32911640 PMCID: PMC7558503 DOI: 10.3390/antibiotics9090586] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 08/27/2020] [Accepted: 09/07/2020] [Indexed: 01/31/2023] Open
Abstract
Grapefruit and lemon pectin obtained from the respective waste citrus peels via hydrodynamic cavitation in water only are powerful, broad-scope antimicrobials against Gram-negative and -positive bacteria. Dubbed IntegroPectin, these pectic polymers functionalized with citrus flavonoids and terpenes show superior antimicrobial activity when compared to commercial citrus pectin. Similar to commercial pectin, lemon IntegroPectin determined ca. 3-log reduction in Staphylococcus aureus cells, while an enhanced activity of commercial citrus pectin was detected in the case of Pseudomonas aeruginosa cells with a minimal bactericidal concentration (MBC) of 15 mg mL−1. Although grapefruit and lemon IntegroPectin share equal MBC in the case of P. aeruginosa cells, grapefruit IntegroPectin shows boosted activity upon exposure of S. aureus cells with a 40 mg mL−1 biopolymer concentration affording complete killing of the bacterial cells. Insights into the mechanism of action of these biocompatible antimicrobials and their effect on bacterial cells, at the morphological level, were obtained indirectly through Fourier Transform Infrared spectroscopy and directly through scanning electron microscopy. In the era of antimicrobial resistance, these results are of great societal and sanitary relevance since citrus IntegroPectin biomaterials are also devoid of cytotoxic activity, as already shown for lemon IntegroPectin, opening the route to the development of new medical treatments of polymicrobial infections unlikely to develop drug resistance.
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Affiliation(s)
- Alessandro Presentato
- Department of Biological, Chemical, and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy; (A.P.); (E.P.); (D.C.M.)
| | - Elena Piacenza
- Department of Biological, Chemical, and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy; (A.P.); (E.P.); (D.C.M.)
- National Interuniversity Consortium of Materials Science and Technology (INSTM), Via G. Giusti 9, 50121 Firenze, Italy
| | - Antonino Scurria
- Istituto per lo Studio dei Materiali Nanostrutturati, CNR, via U. La Malfa 153, 90146 Palermo, Italy; (A.S.); (R.C.)
| | - Lorenzo Albanese
- Istituto per la Bioeconomia, CNR, via Madonna del Piano 10, 50019 Sesto Fiorentino, FI, Italy; (L.A.); (F.Z.); (F.M.)
| | - Federica Zabini
- Istituto per la Bioeconomia, CNR, via Madonna del Piano 10, 50019 Sesto Fiorentino, FI, Italy; (L.A.); (F.Z.); (F.M.)
| | - Francesco Meneguzzo
- Istituto per la Bioeconomia, CNR, via Madonna del Piano 10, 50019 Sesto Fiorentino, FI, Italy; (L.A.); (F.Z.); (F.M.)
| | - Domenico Nuzzo
- Istituto per la Ricerca e l’Innovazione Biomedica, CNR, via U. La Malfa 153, 90146 Palermo, Italy;
| | - Mario Pagliaro
- Istituto per lo Studio dei Materiali Nanostrutturati, CNR, via U. La Malfa 153, 90146 Palermo, Italy; (A.S.); (R.C.)
- Correspondence: (M.P.); (R.A.)
| | - Delia Chillura Martino
- Department of Biological, Chemical, and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy; (A.P.); (E.P.); (D.C.M.)
- National Interuniversity Consortium of Materials Science and Technology (INSTM), Via G. Giusti 9, 50121 Firenze, Italy
| | - Rosa Alduina
- Department of Biological, Chemical, and Pharmaceutical Science and Technology (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy; (A.P.); (E.P.); (D.C.M.)
- Correspondence: (M.P.); (R.A.)
| | - Rosaria Ciriminna
- Istituto per lo Studio dei Materiali Nanostrutturati, CNR, via U. La Malfa 153, 90146 Palermo, Italy; (A.S.); (R.C.)
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Schilcher K, Horswill AR. Staphylococcal Biofilm Development: Structure, Regulation, and Treatment Strategies. Microbiol Mol Biol Rev 2020; 84:e00026-19. [PMID: 32792334 PMCID: PMC7430342 DOI: 10.1128/mmbr.00026-19] [Citation(s) in RCA: 380] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In many natural and clinical settings, bacteria are associated with some type of biotic or abiotic surface that enables them to form biofilms, a multicellular lifestyle with bacteria embedded in an extracellular matrix. Staphylococcus aureus and Staphylococcus epidermidis, the most frequent causes of biofilm-associated infections on indwelling medical devices, can switch between an existence as single free-floating cells and multicellular biofilms. During biofilm formation, cells first attach to a surface and then multiply to form microcolonies. They subsequently produce the extracellular matrix, a hallmark of biofilm formation, which consists of polysaccharides, proteins, and extracellular DNA. After biofilm maturation into three-dimensional structures, the biofilm community undergoes a disassembly process that leads to the dissemination of staphylococcal cells. As biofilms are dynamic and complex biological systems, staphylococci have evolved a vast network of regulatory mechanisms to modify and fine-tune biofilm development upon changes in environmental conditions. Thus, biofilm formation is used as a strategy for survival and persistence in the human host and can serve as a reservoir for spreading to new infection sites. Moreover, staphylococcal biofilms provide enhanced resilience toward antibiotics and the immune response and impose remarkable therapeutic challenges in clinics worldwide. This review provides an overview and an updated perspective on staphylococcal biofilms, describing the characteristic features of biofilm formation, the structural and functional properties of the biofilm matrix, and the most important mechanisms involved in the regulation of staphylococcal biofilm formation. Finally, we highlight promising strategies and technologies, including multitargeted or combinational therapies, to eradicate staphylococcal biofilms.
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Affiliation(s)
- Katrin Schilcher
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Department of Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado, USA
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24
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Schilcher K, Horswill AR. Staphylococcal Biofilm Development: Structure, Regulation, and Treatment Strategies. Microbiol Mol Biol Rev 2020. [PMID: 32792334 DOI: 10.1128/mmbr.00026-19/asset/e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023] Open
Abstract
In many natural and clinical settings, bacteria are associated with some type of biotic or abiotic surface that enables them to form biofilms, a multicellular lifestyle with bacteria embedded in an extracellular matrix. Staphylococcus aureus and Staphylococcus epidermidis, the most frequent causes of biofilm-associated infections on indwelling medical devices, can switch between an existence as single free-floating cells and multicellular biofilms. During biofilm formation, cells first attach to a surface and then multiply to form microcolonies. They subsequently produce the extracellular matrix, a hallmark of biofilm formation, which consists of polysaccharides, proteins, and extracellular DNA. After biofilm maturation into three-dimensional structures, the biofilm community undergoes a disassembly process that leads to the dissemination of staphylococcal cells. As biofilms are dynamic and complex biological systems, staphylococci have evolved a vast network of regulatory mechanisms to modify and fine-tune biofilm development upon changes in environmental conditions. Thus, biofilm formation is used as a strategy for survival and persistence in the human host and can serve as a reservoir for spreading to new infection sites. Moreover, staphylococcal biofilms provide enhanced resilience toward antibiotics and the immune response and impose remarkable therapeutic challenges in clinics worldwide. This review provides an overview and an updated perspective on staphylococcal biofilms, describing the characteristic features of biofilm formation, the structural and functional properties of the biofilm matrix, and the most important mechanisms involved in the regulation of staphylococcal biofilm formation. Finally, we highlight promising strategies and technologies, including multitargeted or combinational therapies, to eradicate staphylococcal biofilms.
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Affiliation(s)
- Katrin Schilcher
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Department of Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado, USA
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25
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Kuehl R, Morata L, Meylan S, Mensa J, Soriano A. When antibiotics fail: a clinical and microbiological perspective on antibiotic tolerance and persistence of Staphylococcus aureus. J Antimicrob Chemother 2020; 75:1071-1086. [PMID: 32016348 DOI: 10.1093/jac/dkz559] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen causing a vast array of infections with significant mortality. Its versatile physiology enables it to adapt to various environments. Specific physiological changes are thought to underlie the frequent failure of antimicrobial therapy despite susceptibility in standard microbiological assays. Bacteria capable of surviving high antibiotic concentrations despite having a genetically susceptible background are described as 'antibiotic tolerant'. In this review, we put current knowledge on environmental triggers and molecular mechanisms of increased antibiotic survival of S. aureus into its clinical context. We discuss animal and clinical evidence of its significance and outline strategies to overcome infections with antibiotic-tolerant S. aureus.
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Affiliation(s)
- Richard Kuehl
- Service of Infectious Diseases, Hospital Clinic of Barcelona, University of Barcelona, IDIBAPS, Barcelona, Spain
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel, Switzerland
| | - Laura Morata
- Service of Infectious Diseases, Hospital Clinic of Barcelona, University of Barcelona, IDIBAPS, Barcelona, Spain
| | - Sylvain Meylan
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel, Switzerland
- Division de Maladies Infectieuses, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Josep Mensa
- Service of Infectious Diseases, Hospital Clinic of Barcelona, University of Barcelona, IDIBAPS, Barcelona, Spain
| | - Alex Soriano
- Service of Infectious Diseases, Hospital Clinic of Barcelona, University of Barcelona, IDIBAPS, Barcelona, Spain
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26
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Ahn SJ, Desai S, Blanco L, Lin M, Rice KC. Acetate and Potassium Modulate the Stationary-Phase Activation of lrgAB in Streptococcus mutans. Front Microbiol 2020; 11:401. [PMID: 32231651 PMCID: PMC7082836 DOI: 10.3389/fmicb.2020.00401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/26/2020] [Indexed: 12/28/2022] Open
Abstract
Fluctuating environments force bacteria to constantly adapt and optimize the uptake of substrates to maintain cellular and nutritional homeostasis. Our recent findings revealed that LrgAB functions as a pyruvate uptake system in Streptococcus mutans, and its activity is modulated in response to glucose and oxygen levels. Here, we show that the composition of the growth medium dramatically influences the magnitude and pattern of lrgAB activation. Specifically, tryptone (T) medium does not provide a preferred environment for stationary phase lrgAB activation, which is independent of external pyruvate concentration. The addition of pyruvate to T medium can elicit PlrgA activation during exponential growth, enabling the cell to utilize external pyruvate for improvement of cell growth. Through comparison of the medium composition and a series of GFP quantification assays for measurement of PlrgA activation, we found that acetate and potassium (K+) play important roles in eliciting PlrgA activation at stationary phase. Of note, supplementation of pooled human saliva to T medium induced lrgAB expression at stationary phase and in response to pyruvate, suggesting that LrgAB is likely functional in the oral cavity. High concentrations of acetate inhibit cell growth, while high concentrations of K+ negatively regulate lrgAB activation. qPCR analysis also revealed that growth in T medium (acetate/K+ limited) significantly affects the expression of genes related to the catabolic pathways of pyruvate, including the Pta/AckA pathway (acetate metabolism). Lastly, stationary phase lrgAB expression is not activated when S. mutans is cultured in T medium, even in a strain that overexpresses lytST. Taken together, these data suggest that lrgAB activation and pyruvate uptake in S. mutans are connected to acetate metabolism and potassium uptake systems, important for cellular and energy homeostasis. They also suggest that these factors need to be implemented when planning metabolic experiments and analyzing data in S. mutans studies that may be sensitive to stationary growth phase.
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Affiliation(s)
- Sang-Joon Ahn
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, United States
| | - Shailja Desai
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, United States
| | - Loraine Blanco
- Department of Biology, College of Liberal Arts and Sciences, University of Florida, Gainesville, FL, United States
| | - Min Lin
- Department of Chemistry, College of Liberal Arts and Sciences, University of Florida, Gainesville, FL, United States
| | - Kelly C Rice
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, United States
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27
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Liu L, Shen X, Yu J, Cao X, Zhan Q, Guo Y, Yu F. Subinhibitory Concentrations of Fusidic Acid May Reduce the Virulence of S. aureus by Down-Regulating sarA and saeRS to Reduce Biofilm Formation and α-Toxin Expression. Front Microbiol 2020; 11:25. [PMID: 32117092 PMCID: PMC7033611 DOI: 10.3389/fmicb.2020.00025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 01/08/2020] [Indexed: 01/08/2023] Open
Abstract
Staphylococcus aureus is an important pathogen in hospital and community infections. Fusidic acid is particularly effective in treating skin and wound infections caused by staphylococci. The purpose of our study was to clarify the effect of fusidic acid on the biofilm formation and α-toxin expression of S. aureus at subinhibitory concentrations [1/64, 1/32, and 1/16 × minimum inhibitory concentration (MIC)]. A total of 504 genes greater than a twofold or less than twofold change in expression of S. aureus effected by subinhibitory concentrations of fusidic acid were found, including 232 up-regulated genes and 272 down-regulated genes, which were determined by transcriptome sequencing. Our results showed subinhibitory concentrations of fusidic acid significantly inhibited the expression of hla, spa, icaA, and cidA at the mRNA level in clinical S. aureus strains tested. And subinhibitory concentrations of fusidic acid can significantly reduce the hemolysis activity and α-toxin production of S. aureus. In addition, the subinhibitory concentrations of fusidic acid significantly inhibited biofilm formation, autolysis, cell aggregation, and polysaccharide intercellular adhesin (PIA) production of S. aureus. Moreover, fusidic acid effectively reduces the damage of mouse skin lesion area. Furthermore, fusidic acid reduced the expression of the two-component regulatory system saeRS and staphylococcal accessory gene regulator (sarA). In conclusion, our results suggested that the subinhibitory concentrations of fusidic acid may reduce the virulence of S. aureus by down-regulating sarA and saeRS to reduce biofilm formation and α-toxin expression, which will provide a theoretical basis for the clinical treatment of S. aureus infection. This is the first report that fusidic acid has an inhibitory effect on the virulence of S. aureus, and this broadens the clinical application of fusidic acid.
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Affiliation(s)
- Li Liu
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xiaofei Shen
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jingyi Yu
- Department of Laboratory Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xingwei Cao
- Jiangxi Provincial Key Laboratory of Medicine, Clinical Laboratory of the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Qing Zhan
- Jiangxi Provincial Key Laboratory of Preventive Medicine, Nanchang University, Nanchang, China
| | - Yinjuan Guo
- Department of Clinical Laboratory, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
| | - Fangyou Yu
- Department of Clinical Laboratory, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China
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28
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CidR and CcpA Synergistically Regulate Staphylococcus aureus cidABC Expression. J Bacteriol 2019; 201:JB.00371-19. [PMID: 31501288 DOI: 10.1128/jb.00371-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 09/04/2019] [Indexed: 12/18/2022] Open
Abstract
The death and lysis of a subpopulation of Staphylococcus aureus cells during biofilm development benefit the whole bacterial population through the release of an important component of the biofilm matrix, extracellular DNA. Previously, we have demonstrated that these processes are affected by the gene products of the cidABC operon, the expression of which is controlled by the LysR-type transcriptional regulator, CidR. In this study, we characterized cis- and trans-acting elements essential for the induction of the cidABC operon. In addition to a CidR-binding site located within the cidABC promoter region, sequence analysis revealed the presence of a putative catabolite responsive element (cre box), suggestive of the involvement of the catabolite control protein A (CcpA) in the regulation of cidABC expression. This was confirmed using electrophoretic mobility shift assays and real-time reverse transcriptase PCR analysis demonstrating the direct positive control of cidABC transcription by the master regulator of carbon metabolism. Furthermore, the importance of CcpA and the identified cre site for the induction of the cidABC operon was demonstrated by examining the expression of P cidABC-lacZ reporter fusions in various mutant strains in which the genes involved in carbon metabolism and carbon catabolite repression were disrupted. Together the results of this study demonstrate the necessity of both transcriptional regulators, CidR and CcpA, for the induction of the cidABC operon and reveal the complexity of molecular interactions controlling its expression.IMPORTANCE This work focuses on the characterization of cis- and trans-acting elements essential for the induction of the cidABC operon in S. aureus The results of this study are the first to demonstrate the synergistic control of cidABC expression by transcriptional regulators CidR and CcpA during carbohydrate metabolism. We established that the full induction of cidABC expression depends on the metabolic state of bacteria and requires both CidR and CcpA. Together, these findings delineate regulatory control of cidABC expression under different metabolic conditions and provide important new insights into our understanding of cell death mechanisms during biofilm development in S. aureus.
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29
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Four LysR-type transcriptional regulator family proteins (LTTRs) involved in antibiotic resistance in Aeromonas hydrophila. World J Microbiol Biotechnol 2019; 35:127. [DOI: 10.1007/s11274-019-2700-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 07/22/2019] [Indexed: 01/21/2023]
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30
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Piacenza E, Presentato A, Ambrosi E, Speghini A, Turner RJ, Vallini G, Lampis S. Physical-Chemical Properties of Biogenic Selenium Nanostructures Produced by Stenotrophomonas maltophilia SeITE02 and Ochrobactrum sp. MPV1. Front Microbiol 2018; 9:3178. [PMID: 30619230 PMCID: PMC6306038 DOI: 10.3389/fmicb.2018.03178] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/07/2018] [Indexed: 01/22/2023] Open
Abstract
Stenotrophomonas maltophilia SeITE02 and Ochrobactrum sp. MPV1 were isolated from the rhizosphere soil of the selenium-hyperaccumulator legume Astragalus bisulcatus and waste material from a dumping site for roasted pyrites, respectively. Here, these bacterial strains were studied as cell factories to generate selenium-nanostructures (SeNS) under metabolically controlled growth conditions. Thus, a defined medium (DM) containing either glucose or pyruvate as carbon and energy source along with selenite () was tested to evaluate bacterial growth, oxyanion bioconversion and changes occurring in SeNS features with respect to those generated by these strains grown on rich media. Transmission electron microscopy (TEM) images show extra- or intra-cellular emergence of SeNS in SeITE02 or MPV1 respectively, revealing the presence of two distinct biological routes of SeNS biogenesis. Indeed, the stress exerted by upon SeITE02 cells triggered the production of membrane vesicles (MVs), which surrounded Se-nanoparticles (SeNPsSeITE02-G_e and SeNPsSeITE02-P_e with average diameter of 179 ± 56 and 208 ± 60 nm, respectively), as highlighted by TEM and scanning electron microscopy (SEM), strongly suggesting that MVs might play a crucial role in the excreting mechanism of the SeNPs in the extracellular environment. On the other hand, MPV1 strain biosynthesized intracellular inclusions likely containing hydrophobic storage compounds and SeNPs (123 ± 32 nm) under pyruvate conditioning, while the growth on glucose as the only source of carbon and energy led to the production of a mixed population of intracellular SeNPs (118 ± 36 nm) and nanorods (SeNRs; average length of 324 ± 89). SEM, fluorescence spectroscopy, and confocal laser scanning microscopy (CLSM) revealed that the biogenic SeNS were enclosed in an organic material containing proteins and amphiphilic molecules, possibly responsible for the high thermodynamic stability of these nanomaterials. Finally, the biogenic SeNS extracts were photoluminescent upon excitation ranging from 380 to 530 nm, whose degree of fluorescence emission (λem = 416–640 nm) was comparable to that from chemically synthesized SeNPs with L-cysteine (L-cys SeNPs). This study offers novel insights into the formation, localization, and release of biogenic SeNS generated by two different Gram-negative bacterial strains under aerobic and metabolically controlled growth conditions. The work strengthens the possibility of using these bacterial isolates as eco-friendly biocatalysts to produce high quality SeNS targeted to possible biomedical applications and other biotechnological purposes.
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Affiliation(s)
- Elena Piacenza
- Environmental Microbiology and Microbial Biotechnology Laboratory, Department of Biotechnology, University of Verona, Verona, Italy.,Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Alessandro Presentato
- Environmental Microbiology and Microbial Biotechnology Laboratory, Department of Biotechnology, University of Verona, Verona, Italy
| | - Emmanuele Ambrosi
- Department of Molecular Sciences and Nanosystems, Ca'Foscari University, Venezia, Italy
| | - Adolfo Speghini
- Nanomaterials Research Group, Department of Biotechnology, University of Verona and INSTM, Verona, Italy
| | - Raymond J Turner
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Giovanni Vallini
- Environmental Microbiology and Microbial Biotechnology Laboratory, Department of Biotechnology, University of Verona, Verona, Italy
| | - Silvia Lampis
- Environmental Microbiology and Microbial Biotechnology Laboratory, Department of Biotechnology, University of Verona, Verona, Italy
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31
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Lee GY, Kang KM, Back SH, Baek JY, Kim SH, Park JH, Yang SJ. Adaptations of Vancomycin-Intermediate Sequence Type 72 Methicillin-Resistant Staphylococcus aureus for Daptomycin Nonsusceptibility. Microb Drug Resist 2018; 24:1489-1496. [PMID: 29927700 DOI: 10.1089/mdr.2018.0112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In Korea, the major clonal type of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is sequence type 72 (ST72) with staphylococcal cassette chromosome mec (SCCmec) type IV (ST72-MRSA-IV). In this study, we used a previously well-characterized isogenic pair of ST72 vancomycin (VAN) susceptible-and VAN intermediate-MRSA strains (VSSA303 and VISA072) and several VSSA strains complemented with plasmids expressing single-point mutated genes (dprAG196C, femAF92C, vraRE127K, and vraSRE127K) identified in the VISA strain. Using the strain set, we assessed the (1) susceptibilities to daptomycin (DAP) and cationic antimicrobial peptides (CAMPs), (2) alterations in cell envelope phenotypes, such as cell wall autolysis, surface positive charge, and membrane potential (ΔΨ), (3) transcriptional expression profiles of genes involved in surface charge regulation and changes of ΔΨ, and (4) cytokine stimulation profiles in murine macrophages. The vraRE127K mutation could enhance surface positive charge through mprF- and dltABCD-independent mechanisms with thickened cell wall. However, none of the single-point mutated genes increased DAP resistance. The DAP nonsusceptible (DAP-NS) phenotype observed in VISA072 strain likely resulted from the combined effects of low ΔΨ and increased positive surface charge. These results suggest that physicochemical alterations in cell envelope are involved in the survival response of DAP-NS VISA072 in sites of infections.
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Affiliation(s)
- Gi Yong Lee
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Kyung Mi Kang
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Seung Hyun Back
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
| | - Jin Yang Baek
- 2 Asia Pacific Foundation for Infectious Diseases (APFID) , Seoul, Korea
- 3 Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea
| | - So Hyun Kim
- 2 Asia Pacific Foundation for Infectious Diseases (APFID) , Seoul, Korea
- 3 Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine , Seoul, Korea
| | - Jong-Hwan Park
- 4 Laboratory Animal Medicine, College of Veterinary Medicine, Chonnam National University , Gwangju, Korea
| | - Soo-Jin Yang
- 1 School of Bioresources and Bioscience, Chung-Ang University , Anseong, Korea
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32
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Claunch KM, Bush M, Evans CR, Malmquist JA, Hale MC, McGillivray SM. Transcriptional profiling of the clpX mutant in Bacillus anthracis reveals regulatory connection with the lrgAB operon. MICROBIOLOGY-SGM 2018; 164:659-669. [PMID: 29473820 DOI: 10.1099/mic.0.000628] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
ClpX functions as either an independent chaperone or a component of the ClpXP protease, a conserved intracellular protease that acts as a global regulator in the bacterial cell by degrading regulatory proteins, stress response proteins and rate-limiting enzymes. Previously, we found that loss of clpX in Bacillus anthracis Sterne leads to increased susceptibility to antimicrobial agents that target the cell envelope. The aim of this study was to identify genes within the regulatory network of clpX that contribute to antimicrobial resistance. Using microarray analysis, we found 119 genes that are highly differentially expressed in the ∆clpX mutant, with the majority involved in metabolic, transport or regulatory functions. Several of these differentially expressed genes, including glpF, sigM, mrsA, lrgA and lrgB, are associated with cell wall-active antibiotics in other bacterial species. We focused on lrgA and lrgB, which form the lrgAB operon and are downregulated in ∆clpX, because loss of lrgAB increases autolytic activity and penicillin susceptibility in Staphylococcus aureus. While we observed no changes in autolytic activity in either ∆clpX or ∆lrgAB B. anthracis Sterne, we find that both mutants have increased susceptibility to the antimicrobial peptide LL-37 and daptomycin. However, phenotypes between ∆clpX and ∆lrgAB are not identical as ∆clpX also displays increased susceptibility to penicillin and nisin but ∆lrgAB does not. Therefore, while decreased expression of lrgAB may be partially responsible for the increased antimicrobial susceptibility seen in the ∆clpX mutant, disruption of other pathways must also contribute to this phenotype.
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Affiliation(s)
- Kevin M Claunch
- Department of Biology, Texas Christian University, Fort Worth, TX, USA.,Present address: Texas A&M Health Science Center College of Medicine, Bryan, TX, USA
| | - Madeline Bush
- Department of Biology, Texas Christian University, Fort Worth, TX, USA.,Present address: St. Jude Graduate School of Biomedical Sciences, Memphis TN, USA
| | - Christopher R Evans
- Department of Biology, Texas Christian University, Fort Worth, TX, USA.,Present address: Department of Microbiology and Molecular Genetics, McGovern Medical School, Houston, TX, USA
| | - Jacob A Malmquist
- Department of Biology, Texas Christian University, Fort Worth, TX, USA
| | - Matthew C Hale
- Department of Biology, Texas Christian University, Fort Worth, TX, USA
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33
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For the greater good: Programmed cell death in bacterial communities. Microbiol Res 2017; 207:161-169. [PMID: 29458850 DOI: 10.1016/j.micres.2017.11.016] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 11/25/2017] [Accepted: 11/28/2017] [Indexed: 12/21/2022]
Abstract
For a long a time programmed cell death was thought to be a unique characteristic of higher eukaryotes, but evidence has accumulated showing that programmed cell death is a universal phenomenon in all life forms. Many different types of bacterial programmed cell death systems have been identified, rivalling the eukaryotic systems in diversity. Bacteria are singular, seemingly independently living organisms, however they are part of complex communities. Being part of a community seems indispensable for survival in different environments. This review is focussed on the mechanism of and reasons for bacterial programmed cell death in the context of bacterial communities.
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Peng Q, Wu J, Chen X, Qiu L, Zhang J, Tian H, Song F. Disruption of Two-component System LytSR Affects Forespore Engulfment in Bacillus thuringiensis. Front Cell Infect Microbiol 2017; 7:468. [PMID: 29164075 PMCID: PMC5675857 DOI: 10.3389/fcimb.2017.00468] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 10/23/2017] [Indexed: 11/13/2022] Open
Abstract
Two-component regulatory systems (TCSs) play pivotal roles in bacteria sensing many different stimuli from environment. Here, we investigated the role of the LytSR TCS in spore formation in Bacillus thuringiensis (Bt) subsp. kurstaki HD73. lacZ gene fusions revealed that the transcription of the downstream genes, lrgAB, encoding two putative membrane-associated proteins, is regulated by LytSR. The sporulation efficiency of a lytSR mutant was significantly lower than that of wild-type HD73. A confocal microscopic analysis demonstrated that LytSR modulates the process of forespore engulfment. Moreover, the transcription of the lytSR operon is regulated by the mother-cell transcription factor SigE, whereas the transcription of the sporulation gene spoIIP was reduced in the lytSR mutant, as demonstrated with a β-galactosidase activity assay. These results suggest that LytSR modulates forespore engulfment by affecting the transcription of the spoIIP gene in Bt.
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Affiliation(s)
- Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jianbo Wu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.,Institute of Food Science and Technology, Hebei Agricultural University, Baoding, China
| | - Xiaomin Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lili Qiu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hongtao Tian
- Institute of Food Science and Technology, Hebei Agricultural University, Baoding, China
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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The CodY-dependent clhAB2 operon is involved in cell shape, chaining and autolysis in Bacillus cereus ATCC 14579. PLoS One 2017; 12:e0184975. [PMID: 28991912 PMCID: PMC5633148 DOI: 10.1371/journal.pone.0184975] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 09/05/2017] [Indexed: 11/19/2022] Open
Abstract
The Gram-positive pathogen Bacillus cereus is able to grow in chains of rod-shaped cells, but the regulation of chaining remains largely unknown. Here, we observe that glucose-grown cells of B. cereus ATCC 14579 form longer chains than those grown in the absence of glucose during the late exponential and transition growth phases, and identify that the clhAB2 operon is required for this chain lengthening phenotype. The clhAB2 operon is specific to the B. cereus group (i.e., B. thuringiensis, B. anthracis and B. cereus) and encodes two membrane proteins of unknown function, which are homologous to the Staphylococcus aureus CidA and CidB proteins involved in cell death control within glucose-grown cells. A deletion mutant (ΔclhAB2) was constructed and our quantitative image analyses show that ΔclhAB2 cells formed abnormal short chains regardless of the presence of glucose. We also found that glucose-grown cells of ΔclhAB2 were significantly wider than wild-type cells (1.47 μm ±CI95% 0.04 vs 1.19 μm ±CI95% 0.03, respectively), suggesting an alteration of the bacterial cell wall. Remarkably, ΔclhAB2 cells showed accelerated autolysis under autolysis-inducing conditions, compared to wild-type cells. Overall, our data suggest that the B. cereus clhAB2 operon modulates peptidoglycan hydrolase activity, which is required for proper cell shape and chain length during cell growth, and down-regulates autolysin activity. Lastly, we studied the transcription of clhAB2 using a lacZ transcriptional reporter in wild-type, ccpA and codY deletion-mutant strains. We found that the global transcriptional regulatory protein CodY is required for the basal level of clhAB2 expression under all conditions tested, including the transition growth phase while CcpA, the major global carbon regulator, is needed for the high-level expression of clhAB2 in glucose-grown cells.
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Abstract
Recent studies have revealed an important role for the Staphylococcus aureus CidC enzyme in cell death during the stationary phase and in biofilm development and have contributed to our understanding of the metabolic processes that are important in the induction of bacterial programmed cell death (PCD). To gain more insight into the characteristics of this enzyme, we performed an in-depth biochemical and biophysical analysis of its catalytic properties. In vitro experiments show that this flavoprotein catalyzes the oxidative decarboxylation of pyruvate to acetate and carbon dioxide. CidC efficiently reduces menadione, but not CoenzymeQ0, suggesting a specific role in the S. aureus respiratory chain. CidC exists as a monomer under neutral-pH conditions but tends to aggregate and bind to artificial lipid membranes at acidic pH, resulting in enhanced enzymatic activity. Unlike its Escherichia coli counterpart, PoxB, CidC does not appear to be activated by other amphiphiles like Triton X-100 or octyl β-d-glucopyranoside. In addition, only reduced CidC is protected from proteolytic cleavage by chymotrypsin, and unlike its homologues in other bacteria, protease treatment does not increase CidC enzymatic activity. Finally, CidC exhibits maximal activity at pH 5.5-5.8 and negligible activity at pH 7-8. The results of this study are consistent with a model in which CidC functions as a pyruvate:menaquinone oxidoreductase whose activity is induced at the cellular membrane during cytoplasmic acidification, a process previously shown to be important for the induction of bacterial PCD.
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Affiliation(s)
- Xinyan Zhang
- Department of Pharmaceutical Sciences and ‡Department of Pathology & Microbiology, University of Nebraska Medical Center , Omaha, Nebraska 68198-5900, United States
| | - Kenneth W Bayles
- Department of Pharmaceutical Sciences and ‡Department of Pathology & Microbiology, University of Nebraska Medical Center , Omaha, Nebraska 68198-5900, United States
| | - Sorin Luca
- Department of Pharmaceutical Sciences and ‡Department of Pathology & Microbiology, University of Nebraska Medical Center , Omaha, Nebraska 68198-5900, United States
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Rice KC, Turner ME, Carney OV, Gu T, Ahn SJ. Modification of the Streptococcus mutans transcriptome by LrgAB and environmental stressors. Microb Genom 2017; 3:e000104. [PMID: 28348880 PMCID: PMC5361627 DOI: 10.1099/mgen.0.000104] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 12/20/2016] [Indexed: 12/14/2022] Open
Abstract
The Streptococcus mutans Cid/Lrg system is central to the physiology of this cariogenic organism, affecting oxidative stress resistance, biofilm formation and competence. Previous transcriptome analyses of lytS (responsible for the regulation of lrgAB expression) and cidB mutants have revealed pleiotropic effects on carbohydrate metabolism and stress resistance genes. In this study, it was found that an lrgAB mutant, previously shown to have diminished aerobic and oxidative stress growth, was also much more growth impaired in the presence of heat and vancomycin stresses, relative to wild-type, lrgA and lrgB mutants. To obtain a more holistic picture of LrgAB and its involvement in stress resistance, RNA sequencing and bioinformatics analyses were used to assess the transcriptional response of wild-type and isogenic lrgAB mutants under anaerobic (control) and stress-inducing culture conditions (aerobic, heat and vancomycin). Hierarchical clustering and principal components analyses of all differentially expressed genes revealed that the most distinct gene expression profiles between S. mutans UA159 and lrgAB mutant occurred during aerobic and high-temperature growth. Similar to previous studies of a cidB mutant, lrgAB stress transcriptomes were characterized by a variety of gene expression changes related to genomic islands, CRISPR-C as systems, ABC transporters, competence, bacteriocins, glucosyltransferases, protein translation, tricarboxylic acid cycle, carbohydrate metabolism/storage and transport. Notably, expression of lrgAB was upregulated in the wild-type strain under all three stress conditions. Collectively, these results demonstrate that mutation of lrgAB alters the transcriptional response to stress, and further support the idea that the Cid/Lrg system acts to promote cell homeostasis in the face of environmental stress.
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Affiliation(s)
- Kelly C Rice
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - Matthew E Turner
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - O'neshia V Carney
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.,†Present address: Department of Health Outcomes and Policy, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Tongjun Gu
- 2Bioinformatics, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32610, USA
| | - Sang-Joon Ahn
- 3Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
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Dakheel KH, Abdul Rahim R, Neela VK, Al-Obaidi JR, Hun TG, Yusoff K. Methicillin-Resistant Staphylococcus aureus Biofilms and Their Influence on Bacterial Adhesion and Cohesion. BIOMED RESEARCH INTERNATIONAL 2016; 2016:4708425. [PMID: 28078291 PMCID: PMC5203895 DOI: 10.1155/2016/4708425] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/08/2016] [Accepted: 11/13/2016] [Indexed: 01/30/2023]
Abstract
Twenty-five methicillin-resistant Staphylococcus aureus (MRSA) isolates were characterized by staphylococcal protein A gene typing and the ability to form biofilms. The presence of exopolysaccharides, proteins, and extracellular DNA and RNA in biofilms was assessed by a dispersal assay. In addition, cell adhesion to surfaces and cell cohesion were evaluated using the packed-bead method and mechanical disruption, respectively. The predominant genotype was spa type t127 (22 out of 25 isolates); the majority of isolates were categorized as moderate biofilm producers. Twelve isolates displayed PIA-independent biofilm formation, while the remaining 13 isolates were PIA-dependent. Both groups showed strong dispersal in response to RNase and DNase digestion followed by proteinase K treatment. PIA-dependent biofilms showed variable dispersal after sodium metaperiodate treatment, whereas PIA-independent biofilms showed enhanced biofilm formation. There was no correlation between the extent of biofilm formation or biofilm components and the adhesion or cohesion abilities of the bacteria, but the efficiency of adherence to glass beads increased after biofilm depletion. In conclusion, nucleic acids and proteins formed the main components of the MRSA clone t127 biofilm matrix, and there seems to be an association between adhesion and cohesion in the biofilms tested.
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Affiliation(s)
- Khulood Hamid Dakheel
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia
| | - Raha Abdul Rahim
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia
| | - Vasantha Kumari Neela
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia
| | - Jameel R. Al-Obaidi
- Agro-Biotechnology Institute Malaysia (ABI), c/o MARDI Headquarters, 43400 Serdang, Selangor, Malaysia
| | - Tan Geok Hun
- Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
| | - Khatijah Yusoff
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia
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van den Esker MH, Kovács ÁT, Kuipers OP. YsbA and LytST are essential for pyruvate utilization in Bacillus subtilis. Environ Microbiol 2016; 19:83-94. [PMID: 27422364 DOI: 10.1111/1462-2920.13454] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 07/12/2016] [Indexed: 12/01/2022]
Abstract
The genome of Bacillus subtilis encodes homologues of the Cid/Lrg network. In other bacterial species, this network consists of holin- and antiholin-like proteins that regulate cell death by controlling murein hydrolase activity. The YsbA protein of B. subtilis is currently annotated as a putative antiholin-like protein that possibly impedes cell death, whereas YwbH is thought to act as holin-like protein. However, the actual functions of YsbA and YwbH in B. subtilis have never been characterized. Therefore, we examined the impact of these proteins on growth and cell death in B. subtilis. We did not find a connection to the regulation of programmed cell death, but instead, our experiments reveal that YsbA and its two-component regulator LytST are essential for growth on pyruvate. Moreover, deletion of ysbA and lytS significantly reduces pyruvate consumption. Our findings suggest that LytST induces ysbA transcription in the presence of pyruvate, and that YsbA is involved in pyruvate utilization presumably by functioning as pyruvate uptake system. We show that B. subtilis excretes pyruvate as overflow metabolite in rich medium, indicating that pyruvate could be a common nutrient in the environment. Hence, YsbA and LytST might play a major role in environmental growth of B. subtilis.
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Affiliation(s)
- Marielle H van den Esker
- Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Ákos T Kovács
- Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Oscar P Kuipers
- Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
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Chaudhari SS, Thomas VC, Sadykov MR, Bose JL, Ahn DJ, Zimmerman MC, Bayles KW. The LysR-type transcriptional regulator, CidR, regulates stationary phase cell death in Staphylococcus aureus. Mol Microbiol 2016; 101:942-53. [PMID: 27253847 DOI: 10.1111/mmi.13433] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2016] [Indexed: 11/29/2022]
Abstract
The Staphylococcus aureus LysR-type transcriptional regulator, CidR, activates the expression of two operons including cidABC and alsSD that display pro- and anti-death functions, respectively. Although several investigations have focused on the functions of different genes associated with these operons, the collective role of the CidR regulon in staphylococcal physiology is not clearly understood. Here we reveal that the primary role of this regulon is to limit acetate-dependent potentiation of cell death in staphylococcal populations. Although both CidB and CidC promote acetate generation and cell death, the CidR-dependent co-activation of CidA and AlsSD counters the effects of CidBC by redirecting intracellular carbon flux towards acetoin formation. From a mechanistic standpoint, we demonstrate that CidB is necessary for full activation of CidC, whereas CidA limits the abundance of CidC in the cell.
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Affiliation(s)
- Sujata S Chaudhari
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA
| | - Vinai C Thomas
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA
| | - Marat R Sadykov
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA
| | - Jeffrey L Bose
- Department of Microbiology, Molecular Genetics and Immunology, The University of Kansas Medical Center, MSN 3029, 3901 Rainbow Boulevard, Kansas City, KS, 66160, USA
| | - Daniel J Ahn
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA
| | - Matthew C Zimmerman
- Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Kenneth W Bayles
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, 68198-5900, USA.
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Prax M, Mechler L, Weidenmaier C, Bertram R. Glucose Augments Killing Efficiency of Daptomycin Challenged Staphylococcus aureus Persisters. PLoS One 2016; 11:e0150907. [PMID: 26960193 PMCID: PMC4784881 DOI: 10.1371/journal.pone.0150907] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 02/21/2016] [Indexed: 02/05/2023] Open
Abstract
Treatment of Staphylococcus aureus in stationary growth phase with high doses of the antibiotic daptomycin (DAP) eradicates the vast majority of the culture and leaves persister cells behind. Despite resting in a drug-tolerant and dormant state, persister cells exhibit metabolic activity which might be exploited for their elimination. We here report that the addition of glucose to S. aureus persisters treated with DAP increased killing by up to five-fold within one hour. This glucose-DAP effect also occurred with strains less sensitive to the drug. The underlying mechanism is independent of the proton motive force and was not observed with non-metabolizable 2-deoxy-glucose. Our results are consistent with two hypotheses on the glucose-DAP interplay. The first is based upon glucose-induced carbohydrate transport proteins that may influence DAP and the second suggests that glucose may trigger the release or activity of cell-lytic proteins to augment DAP’s mode of action.
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Affiliation(s)
- Marcel Prax
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin, Lehrbereich Mikrobielle Genetik, Auf der Morgenstelle 28, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
- Paul-Ehrlich-Institut, Mikrobiologische Sicherheit, Paul-Ehrlich-Str. 51–59, 63225 Langen, Germany
| | - Lukas Mechler
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin, Lehrbereich Mikrobielle Genetik, Auf der Morgenstelle 28, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Christopher Weidenmaier
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin, Medizinische Mikrobiologie und Hygiene, Elfriede-Aulhorn-Str. 6, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Ralph Bertram
- Interfakultäres Institut für Mikrobiologie und Infektionsmedizin, Lehrbereich Mikrobielle Genetik, Auf der Morgenstelle 28, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
- Klinikum Nürnberg Medical School GmbH, Research Department, Paracelsus Medical University, Nuremberg, Germany
- * E-mail:
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Savijoki K, Skogman M, Fallarero A, Nyman TA, Sukura A, Vuorela P, Varmanen P. Penicillin G increases the synthesis of a suicidal marker (CidC) and virulence (HlgBC) proteins in Staphylococcus aureus biofilm cells. Int J Med Microbiol 2016; 306:69-74. [PMID: 26725755 DOI: 10.1016/j.ijmm.2015.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/30/2015] [Accepted: 11/29/2015] [Indexed: 10/22/2022] Open
Abstract
The present study reports the effect of Penicillin G (PenG) on the proteome dynamics of the Staphylococcus aureus strain Newman during biofilm mode of growth. The viability of the 18-h-old biofilm cells challenged with PenG at the concentration of 1mgmL(-1) was first assessed by plate counting, resazurin and LIVE/DEAD fluorescence staining, which indicated that the viability was reduced by ∼35% and ∼90% at 2h and 24h, respectively, after the addition of PenG. Subsequent two-dimensional difference gel electrophoresis (2D DIGE) assay of the treated and non-treated biofilm cells at the indicated time points revealed 45 proteins showing time- and treatment-specific change (1.5-fold, p<0.01). The 2D DIGE results suggested that the PenG-induced decrease in viability was accompanied by an increased synthesis of pyruvate oxidase (CidC), a suicidal marker known to potentiate acetate-dependent cell death in S. aureus. Increased abundance was also found for the TCA cycle associated malate-quinone oxidoreductase (Mqo), the ClpC ATPase, the HlgBC toxin and phage-associated proteins, which suggests that surviving cells have induced these activities as a last effort to overcome lethal doses of PenG. Proteomic results also revealed that the surviving cells were likely to strengthen their peptidoglycan due to the increased abundance of cell-wall biogenesis associated proteins, FemA and Pbp2; a phenomenon associated with dormancy in S. aureus.
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Affiliation(s)
- Kirsi Savijoki
- Department of Food and Environmental Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Finland; Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Finland.
| | - Malena Skogman
- Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Finland
| | - Adyary Fallarero
- Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Finland
| | - Tuula A Nyman
- Institute of Biotechnology, University of Helsinki, Finland
| | - Antti Sukura
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Finland
| | - Pia Vuorela
- Pharmaceutical Biology, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, Finland
| | - Pekka Varmanen
- Department of Food and Environmental Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Finland
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Thorsing M, Bentin T, Givskov M, Tolker-Nielsen T, Goltermann L. The bactericidal activity of β-lactam antibiotics is increased by metabolizable sugar species. MICROBIOLOGY-SGM 2015; 161:1999-2007. [PMID: 26243263 DOI: 10.1099/mic.0.000152] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Here, the influence of metabolizable sugars on the susceptibility of Escherichia coli to β-lactam antibiotics was investigated. Notably, monitoring growth and survival of mono- and combination-treated planktonic cultures showed a 1000- to 10 000-fold higher antibacterial efficacy of carbenicillin and cefuroxime in the presence of certain sugars, whereas other metabolites had no effect on β-lactam sensitivity. This effect was unrelated to changes in growth rate. Light microscopy and flow cytometry profiling revealed that bacterial filaments, formed due to β-lactam-mediated inhibition of cell division, rapidly appeared upon β-lactam mono-treatment and remained stable for up to 18 h. The presence of metabolizable sugars in the medium did not change the rate of filamentation, but led to lysis of the filaments within a few hours. No lysis occurred in E. coli mutants unable to metabolize the sugars, thus establishing sugar metabolism as an important factor influencing the bactericidal outcome of β-lactam treatment. Interestingly, the effect of sugar on β-lactam susceptibility was suppressed in a strain unable to synthesize the nutrient stress alarmone (p)ppGpp. Here, to the best of our knowledge, we demonstrate for the first time a specific and significant increase in β-lactam sensitivity due to sugar metabolism in planktonic, exponentially growing bacteria, unrelated to general nutrient availability or growth rate. Understanding the mechanisms underlying the nutritional influences on antibiotic sensitivity is likely to reveal new proteins or pathways that can be targeted by novel compounds, adding to the list of pharmacodynamic adjuvants that increase the efficiency and lifespan of conventional antibiotics.
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Affiliation(s)
- Mette Thorsing
- Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3b, 2200 Copenhagen, Denmark
| | - Thomas Bentin
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3b, 2200 Copenhagen, Denmark
| | - Michael Givskov
- Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3b, 2200 Copenhagen, Denmark.,Singapore Center on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Tim Tolker-Nielsen
- Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3b, 2200 Copenhagen, Denmark
| | - Lise Goltermann
- Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3b, 2200 Copenhagen, Denmark
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The Matrix Reloaded: Probing the Extracellular Matrix Synchronizes Bacterial Communities. J Bacteriol 2015; 197:2092-2103. [PMID: 25825428 DOI: 10.1128/jb.02516-14] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In response to chemical communication, bacterial cells often organize themselves into complex multicellular communities that carry out specialized tasks. These communities are frequently referred to as biofilms, which involve collective behavior of different cell types. Like cells of multicellular eukaryotes, the biofilm cells are surrounded by self-produced polymers that constitute the extracellular matrix (ECM), which binds them to each other and to the surface. In multicellular eukaryotes, it has been evident for decades that cell-ECM interactions control multiple cellular processes during development. While cells, both in biofilms and in multicellular eukaryotes, are surrounded by ECM and activate various genetic programs, until recently it has been unclear whether cell-ECM interactions are recruited in bacterial communicative behaviors. In this review, we will describe the examples reported thus far for ECM involvement in control of cell behavior throughout the different stages of biofilm formation. The studies presented in this review provide a newly emerging perspective of the bacterial ECM as an active player in regulation of biofilm development.
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Patel K, Golemi-Kotra D. Signaling mechanism by the Staphylococcus aureus two-component system LytSR: role of acetyl phosphate in bypassing the cell membrane electrical potential sensor LytS. F1000Res 2015; 4:79. [PMID: 27127614 PMCID: PMC4830213 DOI: 10.12688/f1000research.6213.2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/17/2016] [Indexed: 01/08/2023] Open
Abstract
The two-component system LytSR has been linked to the signal transduction of cell membrane electrical potential perturbation and is involved in the adaptation of
Staphylococcus aureus to cationic antimicrobial peptides. It consists of a membrane-bound histidine kinase, LytS, which belongs to the family of multiple transmembrane-spanning domains receptors, and a response regulator, LytR, which belongs to the novel family of non-helix-turn-helix DNA-binding domain proteins. LytR regulates the expression of
cidABC and
lrgAB operons, the gene products of which are involved in programmed cell death and lysis.
Invivo studies have demonstrated involvement of two overlapping regulatory networks in regulating the
lrgAB operon, both depending on LytR. One regulatory network responds to glucose metabolism and the other responds to changes in the cell membrane potential. Herein, we show that LytS has autokinase activity and can catalyze a fast phosphotransfer reaction, with 50% of its phosphoryl group lost within 1 minute of incubation with LytR. LytS has also phosphatase activity. Notably, LytR undergoes phosphorylation by acetyl phosphate at a rate that is 2-fold faster than the phosphorylation by LytS. This observation is significant in lieu of the
in vivo observations that regulation of the
lrgAB operon is LytR-dependent in the presence of excess glucose in the medium. The latter condition does not lead to perturbation of the cell membrane potential but rather to the accumulation of acetate in the cell. Our study provides insights into the molecular basis for regulation of
lrgAB in a LytR-dependent manner under conditions that do not involve sensing by LytS.
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Affiliation(s)
- Kevin Patel
- Department of Chemistry, York University, Toronto, Toronto, Ontario, M3J 1P3, Canada
| | - Dasantila Golemi-Kotra
- Department of Chemistry, York University, Toronto, Toronto, Ontario, M3J 1P3, Canada; Department of Biology, York University, Toronto, Toronto, Ontario, M3J 1P3, Canada
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Lehman MK, Bose JL, Sharma-Kuinkel BK, Moormeier DE, Endres JL, Sadykov MR, Biswas I, Bayles KW. Identification of the amino acids essential for LytSR-mediated signal transduction in Staphylococcus aureus and their roles in biofilm-specific gene expression. Mol Microbiol 2015; 95:723-37. [PMID: 25491472 DOI: 10.1111/mmi.12902] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2014] [Indexed: 12/15/2022]
Abstract
Recent studies have demonstrated that expression of the Staphylococcus aureus lrgAB operon is specifically localized within tower structures during biofilm development. To gain a better understanding of the mechanisms underlying this spatial control of lrgAB expression, we carried out a detailed analysis of the LytSR two-component system. Specifically, a conserved aspartic acid (Asp53) of the LytR response regulator was shown to be the target of phosphorylation, which resulted in enhanced binding to the lrgAB promoter and activation of transcription. In addition, we identified His390 of the LytS histidine kinase as the site of autophosphorylation and Asn394 as a critical amino acid involved in phosphatase activity. Interestingly, LytS-independent activation of LytR was observed during planktonic growth, with acetyl phosphate acting as a phosphodonor to LytR. In contrast, mutations disrupting the function of LytS prevented tower-specific lrgAB expression, providing insight into the physiologic environment within these structures. In addition, overactivation of LytR led to increased lrgAB promoter activity during planktonic and biofilm growth and a change in biofilm morphology. Overall, the results of this study are the first to define the LytSR signal transduction pathway, as well as determine the metabolic context within biofilm tower structures that triggers these signaling events.
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Affiliation(s)
- McKenzie K Lehman
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
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Sublethal concentrations of carbapenems alter cell morphology and genomic expression of Klebsiella pneumoniae biofilms. Antimicrob Agents Chemother 2015; 59:1707-17. [PMID: 25583711 DOI: 10.1128/aac.04581-14] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Klebsiella pneumoniae, a Gram-negative bacterium, is normally associated with pneumonia in patients with weakened immune systems. However, it is also a prevalent nosocomial infectious agent that can be found in infected surgical sites and combat wounds. Many of these clinical strains display multidrug resistance. We have worked with a clinical strain of K. pneumoniae that was initially isolated from a wound of an injured soldier. This strain demonstrated resistance to many commonly used antibiotics but sensitivity to carbapenems. This isolate was capable of forming biofilms in vitro, contributing to its increased antibiotic resistance and impaired clearance. We were interested in determining how sublethal concentrations of carbapenem treatment specifically affect K. pneumoniae biofilms both in morphology and in genomic expression. Scanning electron microscopy showed striking morphological differences between untreated and treated biofilms, including rounding, blebbing, and dimpling of treated cells. Comparative transcriptome analysis using RNA sequencing (RNA-Seq) technology identified a large number of open reading frames (ORFs) differentially regulated in response to carbapenem treatment at 2 and 24 h. ORFs upregulated with carbapenem treatment included genes involved in resistance, as well as those coding for antiporters and autoinducers. ORFs downregulated included those coding for metal transporters, membrane biosynthesis proteins, and motility proteins. Quantitative real-time PCR validated the general trend of some of these differentially regulated ORFs. Treatment of K. pneumoniae biofilms with sublethal concentrations of carbapenems induced a wide range of phenotypic and gene expression changes. This study reveals some of the mechanisms underlying how sublethal amounts of carbapenems could affect the overall fitness and pathogenic potential of K. pneumoniae biofilm cells.
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Thomas VC, Sadykov MR, Chaudhari SS, Jones J, Endres JL, Widhelm TJ, Ahn JS, Jawa RS, Zimmerman MC, Bayles KW. A central role for carbon-overflow pathways in the modulation of bacterial cell death. PLoS Pathog 2014; 10:e1004205. [PMID: 24945831 PMCID: PMC4063974 DOI: 10.1371/journal.ppat.1004205] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 05/08/2014] [Indexed: 12/17/2022] Open
Abstract
Similar to developmental programs in eukaryotes, the death of a subpopulation of cells is thought to benefit bacterial biofilm development. However mechanisms that mediate a tight control over cell death are not clearly understood at the population level. Here we reveal that CidR dependent pyruvate oxidase (CidC) and α-acetolactate synthase/decarboxylase (AlsSD) overflow metabolic pathways, which are active during staphylococcal biofilm development, modulate cell death to achieve optimal biofilm biomass. Whereas acetate derived from CidC activity potentiates cell death in cells by a mechanism dependent on intracellular acidification and respiratory inhibition, AlsSD activity effectively counters CidC action by diverting carbon flux towards neutral rather than acidic byproducts and consuming intracellular protons in the process. Furthermore, the physiological features that accompany metabolic activation of cell death bears remarkable similarities to hallmarks of eukaryotic programmed cell death, including the generation of reactive oxygen species and DNA damage. Finally, we demonstrate that the metabolic modulation of cell death not only affects biofilm development but also biofilm-dependent disease outcomes. Given the ubiquity of such carbon overflow pathways in diverse bacterial species, we propose that the metabolic control of cell death may be a fundamental feature of prokaryotic development. Many bacterial species including the pathogen Staphylococcus aureus are capable of adhering to surfaces and forming complex communities called biofilms. This mode of growth can be particularly challenging from an infection control standpoint, as they are often refractory to antibiotics and host immune system. Although developmental processes underlying biofilm formation are not entirely clear, recent evidence suggests that cell death of a subpopulation is crucial for its maturation. In this study we provide insight regarding the metabolic pathways that control cell death and demonstrate that acetate, a by-product of glucose catabolism, potentiates a form of cell death that exhibits physiological and biochemical hallmarks of apoptosis in eukaryotic organisms. Finally, we demonstrate that altering the ability of metabolic pathways that regulate acetate mediated cell death in S. aureus affects the outcome of biofilm-related diseases, such as infective endocarditis.
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Affiliation(s)
- Vinai Chittezham Thomas
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Marat R. Sadykov
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Sujata S. Chaudhari
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Joselyn Jones
- Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Jennifer L. Endres
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Todd J. Widhelm
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Jong-Sam Ahn
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Randeep S. Jawa
- Department of Surgery, Stony Brook University School of Medicine, Stony Brook, New York, United States of America
| | - Matthew C. Zimmerman
- Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Kenneth W. Bayles
- Center for Staphylococcal Research, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail:
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Jenkins R, Burton N, Cooper R. Proteomic and genomic analysis of methicillin-resistant Staphylococcus aureus (MRSA) exposed to manuka honey in vitro demonstrated down-regulation of virulence markers. J Antimicrob Chemother 2013; 69:603-15. [PMID: 24176984 PMCID: PMC3922154 DOI: 10.1093/jac/dkt430] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Objectives Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen. Its resistance to multiple antibiotics and its prevalence in healthcare establishments make it a serious threat to human health that requires novel interventions. Manuka honey is a broad-spectrum antimicrobial agent that is gaining acceptance in the topical treatment of wounds. Because its mode of action is only partially understood, proteomic and genomic analysis was used to investigate the effects of manuka honey on MRSA at a molecular level. Methods Two-dimensional gel electrophoresis with dual-channel imaging was combined with matrix-assisted laser desorption ionization–time of flight mass spectrometry to determine the identities of differentially expressed proteins. The expression of the corresponding genes was investigated by quantitative PCR. Microarray analysis provided an overview of alterations in gene expression across the MRSA genome. Results Genes with increased expression following exposure to manuka honey were associated with glycolysis, transport and biosynthesis of amino acids, proteins and purines. Those with decreased expression were involved in the tricarboxylic acid cycle, cell division, quorum sensing and virulence. The greatest reductions were seen in genes conferring virulence (sec3, fnb, hlgA, lip and hla) and coincided with a down-regulation of global regulators, such as agr, sae and sarV. A model to illustrate these multiple effects was constructed and implicated glucose, which is one of the major sugars contained in honey. Conclusions A decreased expression of virulence genes in MRSA will impact on its pathogenicity and needs to be investigated in vivo.
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Affiliation(s)
- Rowena Jenkins
- Cardiff Metropolitan University, Western Avenue, Cardiff CF5 2YB, UK
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Mutation of RNA polymerase β-subunit gene promotes heterogeneous-to-homogeneous conversion of β-lactam resistance in methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2013; 57:4861-71. [PMID: 23877693 DOI: 10.1128/aac.00720-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three types of phenotypic expression of β-lactam resistance have been reported in methicillin-resistant Staphylococcus aureus (MRSA): heterogeneous, homogeneous, and Eagle-type resistance. Heterogeneous-to-homogeneous conversion of β-lactam resistance is postulated to be caused by a chromosomal mutation (chr*) in addition to the expression of the mecA gene. Eagle-type resistance is a unique phenotype of chr* occurring in pre-MRSA strain N315 whose mecA gene expression is strongly repressed by an intact mecI gene. We here report that certain mutations of the rpoB gene, encoding the RNA polymerase β subunit, belong to chr*. We studied homogeneous MRSA (homo-MRSA) strain N315ΔIP-H5 (abbreviated as ΔIP-H5), which was obtained from hetero-MRSA strain N315ΔIP by selection with 8 mg/liter imipenem. Whole-genome sequencing of ΔIP-H5 revealed the presence of a unique mutation in the rpoB gene, rpoB(N967I), causing the amino acid replacement of Asn by Ile at position 967 of RpoB. The effect of the rpoB(N967I) mutation was confirmed by constructing a revertant H5 rpoB(I967N) strain as well as an N315-derived mutant, N315 rpoB(N967I). H5 rpoB(I967N) regained the hetero-resistance phenotype, and the N315 rpoB(N967I) strain showed an Eagle-type phenotype similar to that of the typical Eagle-type MRSA strain N315h4. Furthermore, subsequent whole-genome sequencing revealed that N315h4 also had a missense mutation of rpoB(R644H). Introduction of the rpoB(N967I) mutation was accompanied by decreased autolysis, prolonged doubling time, and tolerance to bactericidal concentrations of methicillin. We consider that rpoB mutations are the major cause for heterogeneous-to-homogeneous phenotypic conversion of β-lactam resistance in MRSA strain N315 and its derived strains.
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