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Liu L, Wang L, Liu X, Wang B, Guo X, Wang Y, Xu Y, Guan J, Zhao Y. Elucidating the potential of isorhapontigenin in targeting the MgrA regulatory network: a paradigm shift for attenuating MRSA virulence. Antimicrob Agents Chemother 2024; 68:e0061124. [PMID: 39046236 PMCID: PMC11373206 DOI: 10.1128/aac.00611-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Accepted: 07/06/2024] [Indexed: 07/25/2024] Open
Abstract
As methicillin-resistant Staphylococcus aureus (MRSA) exhibits formidable resistance to many drugs, the imperative for alternative therapeutic strategies becomes increasingly evident. At the heart of our study is the identification of a novel inhibitor through fluorescence anisotropy assays, specifically targeting the crucial multiple gene regulator A (MgrA) regulatory network in S. aureus. Isorhapontigenin (Iso), a natural compound, exhibits outstanding inhibitory efficacy, modulating bacterial virulence pathways without exerting direct bactericidal activity. This suggests a paradigm shift toward attenuating virulence instead of purely focusing on bacterial elimination. Through comprehensive in vitro and in vivo evaluations, we elucidated the complex interplay between Iso and MgrA, leading to reduced S. aureus adhesion, and overall virulence. At the cellular level, Iso offers significant protection to A549 cells infected with S. aureus, reducing cellular damage. Importantly, Iso augments the chemotaxis of neutrophils, curtailing the immune evasion capabilities of S. aureus. Furthermore, in vivo investigations highlight the notable effectiveness of Iso against MRSA-induced pneumonia and within the Galleria mellonella infection model, underscoring its pivotal role in the evolving realm of antibacterial drug discovery. Significantly, when Iso is used in combination with vancomycin, it outperforms its solo application, indicating a more pronounced therapeutic impact. This seminal research emphasizes Iso's potential as a primary defense against the surge of multidrug-resistant pathogens, heralding new prospects in antimicrobial therapy.
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Affiliation(s)
- Lihan Liu
- Department of Infectious Diseases and Center of Infectious Diseases and Pathogen Biology, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Jilin University, Changchun, China
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Li Wang
- Clinical Medical College, Changchun University of Chinese Medicine, Changchun, China
| | - Xiaolei Liu
- Department of Infectious Diseases and Center of Infectious Diseases and Pathogen Biology, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Jilin University, Changchun, China
| | - Bingmei Wang
- Clinical Medical College, Changchun University of Chinese Medicine, Changchun, China
| | - Xuerui Guo
- School of Pharmaceutical Science, Jilin University, Changchun, China
| | - Yueying Wang
- Department of Orthopedics, The Third Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, China
| | - Yueshan Xu
- Department of Orthopedics, The Third Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, China
| | - Jiyu Guan
- Department of Infectious Diseases and Center of Infectious Diseases and Pathogen Biology, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Jilin University, Changchun, China
| | - Yicheng Zhao
- Department of Infectious Diseases and Center of Infectious Diseases and Pathogen Biology, State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Jilin University, Changchun, China
- China-Japan Union Hospital of Jilin University, Changchun, China
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Cancino-Diaz ME, Gómez-Chávez F, Cancino-Diaz JC. Presence and mRNA Expression of the sar Family Genes in Clinical and Non-clinical (Healthy Conjunctiva and Healthy Skin) Isolates of Staphylococcus epidermidis. Indian J Microbiol 2024; 64:1301-1309. [PMID: 39282185 PMCID: PMC11399487 DOI: 10.1007/s12088-024-01339-x] [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: 11/09/2023] [Accepted: 06/14/2024] [Indexed: 09/18/2024] Open
Abstract
Staphylococcus aureus possesses sar family genes, including sarA, S, R, T, U, V, X, Y, Z, and rot, which are transcription factors involved in biofilm formation and quorum sensing. In contrast, Staphylococcus epidermidis has sarA, R, V, X, Y, Z, and rot genes; specifically, SarA, Z, and X are involved in biofilm formation. The expression of the sar family members in S. epidermidis isolated from clinical and non-clinical environments is unknown. This study aimed to establish if clinical and non-clinical isolates of S. epidermidis express the sar family members. We genotyped isolates from clinical ocular infections (n = 52), or non-clinical healthy conjunctiva (n = 40), and healthy skin (n = 50), using multilocus sequence typing (MLST) and the staphylococcal chromosomal cassette mec (SCCmec). We selected strains with different genotypes and representatives of each source of isolation, and the presence of the sar family genes was detected using PCR and RT-qPCR to determine their expression. The sar family genes were present in all selected strains, with no observed differences. The relative expression of the sar family showed that all selected strains expressed each gene weakly, with no significant differences observed between them or between different sources of isolation. In conclusion, the presence and relative expression of the sar family genes are very similar among strains, with no differences based on their origin of isolation and genotype. Supplementary Information The online version contains supplementary material available at 10.1007/s12088-024-01339-x.
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Affiliation(s)
- Mario E Cancino-Diaz
- Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, 11350 Ciudad de Mexico, Mexico
| | - Fernando Gómez-Chávez
- Laboratorio de Enfermedades Osteoarticulares E Inmunológicas, Sección de Estudios de Posgrado E Investigación, ENMyH-Instituto Politécnico Nacional, 07320 Ciudad de Mexico, Mexico
| | - Juan C Cancino-Diaz
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, 11350 Ciudad de Mexico, Mexico
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3
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Sato'o Y, Hisatsune J, Aziz F, Tatsukawa N, Shibata-Nakagawa M, Ono HK, Naito I, Omoe K, Sugai M. Coordination of prophage and global regulator leads to high enterotoxin production in staphylococcal food poisoning-associated lineage. Microbiol Spectr 2024; 12:e0292723. [PMID: 38319074 PMCID: PMC10913437 DOI: 10.1128/spectrum.02927-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 01/05/2024] [Indexed: 02/07/2024] Open
Abstract
Staphylococcus species in food produce Staphylococcal enterotoxins (SEs) that cause Staphylococcal food poisoning (SFP). More than 20 SE types have been reported, among which Staphylococcal enterotoxin A (SEA) has been recognized as one of the most important SEs associated with SFP. However, the regulatory mechanisms underlying its production remain unclear. Previously, we identified a major SFP clone in Japan, CC81 subtype-1, which exhibits high SEA production. In this study, we attempted to identify the factors contributing to this phenomenon. Thus, we demonstrated that the attenuation of the activity of endogenous regulator, Staphylococcal accessory regulator S (SarS), and the lysogenization of a high SEA-producing phage contributed to this phenomenon in CC81 subtype-1. Furthermore, our results indicated that SarS could directly bind to the promoter upstream of the sea gene and suppress SEA expression; this low SarS repression activity was identified as one of the reasons for the high SEA production observed. Therefore, we revealed that both exogenous and endogenous factors may probably contribute to the high SEA production. Our results confirmed that SE production is a fundamental and critical factor in SFP and clarified the associated production mechanism while enhancing our understanding as to why a specific clone frequently causes SFP. IMPORTANCE The importance of this study lies in its unveiling of a molecular regulatory mechanism associated with the most important food poisoning toxin and the evolution of Staphylococcal food poisoning (SFP)-associated clone. SFP is primarily caused by Staphylococcus aureus, with Staphylococcal enterotoxin A (SEA) being commonly involved in many cases. Thus, SEA has been recognized as a major toxin type. However, despite almost a century since its discovery, the complete mechanism of SEA production is as yet unknown. In this study, we analyzed an SEA-producing SFP clone isolated in East Asia and discovered that this strain, besides acquiring the high SEA-producing phage, exhibits remarkably high SEA production due to the low activity of SarS, an intrinsic regulatory factor. This is the first report documenting the evolution of the SFP clone through the coordinated action of exogenous mobile genetic factors and endogenous regulators on this notorious toxin.
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Affiliation(s)
- Yusuke Sato'o
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima, Japan
| | - Junzo Hisatsune
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima, Japan
- Antimicrobial Resistance Research Center, National Institute of Infectious Diseases (NIID), Tokyo, Japan
| | - Fatkhanuddin Aziz
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima, Japan
| | - Nobuyuki Tatsukawa
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima, Japan
| | - Mari Shibata-Nakagawa
- Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka city, Japan
| | - Hisaya K. Ono
- Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka city, Japan
- Laboratory of Zoonoses, Kitasato University School of Veterinary Medicine, Towada city, Japan
| | - Ikunori Naito
- Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka city, Japan
| | - Katsuhiko Omoe
- Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka city, Japan
| | - Motoyuki Sugai
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical & Health Sciences, Hiroshima, Japan
- Antimicrobial Resistance Research Center, National Institute of Infectious Diseases (NIID), Tokyo, Japan
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4
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Liu JY, Jia JJ, Liu M, Duan H, Hu ML, Liu C, Xue RY, Jin ZL, Zhang SS, Li GC, Feng R, Jin Z, Li HB, He L. A novel indolylbenzoquinone compound HL-J6 suppresses biofilm formation and α-toxin secretion in methicillin-resistant Staphylococcus aureus. Int J Antimicrob Agents 2023; 62:106972. [PMID: 37741585 DOI: 10.1016/j.ijantimicag.2023.106972] [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: 02/01/2023] [Revised: 08/24/2023] [Accepted: 09/15/2023] [Indexed: 09/25/2023]
Abstract
Eradication of methicillin-resistant Staphylococcus aureus (MRSA) is challenging due to multi-drug resistance of strains and biofilm formation, the latter of which is an important barrier to the penetration of antibiotics and host defences. As such, there is an urgent need to discover and develop novel agents to fight MRSA-associated infection. In this study, HL-J6, a novel indolylbenzoquinone compound, was shown to inhibit S. aureus strains, with a minimum inhibitory concentration against MRSA252 of 2 µg/mL. Moreover, HL-J6 exhibited potent antibiofilm activity in vitro and was able to kill bacteria in biofilm. In the mouse models of wound infection, HL-J6 treatment reduced the MRSA load significantly and inhibited biofilm formation on the wounds. The potent targets of its antibiofilm activity were explored by real-time reverse transcriptase polymerase chain rection, which indicated that HL-J6 downregulated the transcription levels of sarA, atlAE and icaADBC. Moreover, Western blot results showed that HL-J6 reduced the secretion level of α-toxin, a major virulence factor. These findings indicate that HL-J6 is a promising lead compound for the development of novel drugs against MRSA biofilm infections.
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Affiliation(s)
- Jing-Yi Liu
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Jing-Jing Jia
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Engineering Laboratory for Plant-Sourced Drugs and Sichuan Research Centre for Drug Precision Industrial Technology, Department of Medicinal Chemistry, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, China
| | - Ming Liu
- Department of Pharmaceutical Analysis, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Hao Duan
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China; School of Clinical Medicine, Jiamusi University, Jiamusi, Heilongjiang, China
| | - Ming-Li Hu
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Engineering Laboratory for Plant-Sourced Drugs and Sichuan Research Centre for Drug Precision Industrial Technology, Department of Medicinal Chemistry, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, China
| | - Chang Liu
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Ruo-Yi Xue
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Zi-Li Jin
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Shan-Shan Zhang
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China; School of Clinical Medicine, Jiamusi University, Jiamusi, Heilongjiang, China
| | - Guo-Cheng Li
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Rang Feng
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Zhe Jin
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China
| | - Hai-Bo Li
- National Engineering Research Centre of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University (Army Medical University), Chongqing, China.
| | - Ling He
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Engineering Laboratory for Plant-Sourced Drugs and Sichuan Research Centre for Drug Precision Industrial Technology, Department of Medicinal Chemistry, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, China.
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5
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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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Study of SarA by DNA Affinity Capture Assay (DACA) Employing Three Promoters of Key Virulence and Resistance Genes in Methicillin-Resistant Staphylococcus aureus. Antibiotics (Basel) 2022; 11:antibiotics11121714. [PMID: 36551372 PMCID: PMC9774152 DOI: 10.3390/antibiotics11121714] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/21/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA), one of the most well-known human pathogens, houses many virulence factors and regulatory proteins that confer resistance to diverse antibiotics. Although they have been investigated intensively, the correlations among virulence factors, regulatory proteins and antibiotic resistance are still elusive. We aimed to identify the most significant global MRSA regulator by concurrently analyzing protein-binding and several promoters under same conditions and at the same time point. DNA affinity capture assay (DACA) was performed with the promoters of mecA, sarA, and sarR, all of which significantly impact survival of MRSA. Here, we show that SarA protein binds to all three promoters. Consistent with the previous reports, ΔsarA mutant exhibited weakened antibiotic resistance to oxacillin and reduced biofilm formation. Additionally, production and activity of many virulence factors such as phenol-soluble modulins (PSM), α-hemolysin, motility, staphyloxanthin, and other related proteins were decreased. Comparing the sequence of SarA with that of clinical strains of various lineages showed that all sequences were highly conserved, in contrast to that observed for AgrA, another major regulator of virulence and resistance in MRSA. We have demonstrated that SarA regulates antibiotic resistance and the expression of various virulence factors. Our results warrant that SarA could be a leading target for developing therapeutic agents against MRSA infections.
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Gonçalves LG, Santos S, Gomes LP, Armengaud J, Miragaia M, Coelho AV. Skin-to-blood pH shift triggers metabolome and proteome global remodelling in Staphylococcus epidermidis. Front Microbiol 2022; 13:1000737. [PMID: 36246270 PMCID: PMC9554481 DOI: 10.3389/fmicb.2022.1000737] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus epidermidis is one of the most common bacteria of the human skin microbiota. Despite its role as a commensal, S. epidermidis has emerged as an opportunistic pathogen, associated with 80% of medical devices related infections. Moreover, these bacteria are extremely difficult to treat due to their ability to form biofilms and accumulate resistance to almost all classes of antimicrobials. Thus new preventive and therapeutic strategies are urgently needed. However, the molecular mechanisms associated with S. epidermidis colonisation and disease are still poorly understood. A deeper understanding of the metabolic and cellular processes associated with response to environmental factors characteristic of SE ecological niches in health and disease might provide new clues on colonisation and disease processes. Here we studied the impact of pH conditions, mimicking the skin pH (5.5) and blood pH (7.4), in a S. epidermidis commensal strain by means of next-generation proteomics and 1H NMR-based metabolomics. Moreover, we evaluated the metabolic changes occurring during a sudden pH change, simulating the skin barrier break produced by a catheter. We found that exposure of S. epidermidis to skin pH induced oxidative phosphorylation and biosynthesis of peptidoglycan, lipoteichoic acids and betaine. In contrast, at blood pH, the bacterial assimilation of monosaccharides and its oxidation by glycolysis and fermentation was promoted. Additionally, several proteins related to virulence and immune evasion, namely extracellular proteases and membrane iron transporters were more abundant at blood pH. In the situation of an abrupt skin-to-blood pH shift we observed the decrease in the osmolyte betaine and changes in the levels of several metabolites and proteins involved in cellular redoxl homeostasis. Our results suggest that at the skin pH S. epidermidis cells are metabolically more active and adhesion is promoted, while at blood pH, metabolism is tuned down and cells have a more virulent profile. pH increase during commensal-to-pathogen conversion appears to be a critical environmental signal to the remodelling of the S. epidermidis metabolism toward a more pathogenic state. Targeting S. epidermidis proteins induced by pH 7.4 and promoting the acidification of the medical device surface or surrounding environment might be new strategies to treat and prevent S. epidermidis infections.
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Affiliation(s)
- Luis Gafeira Gonçalves
- Laboratory of Proteomics of Non-Model Organisms, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Susana Santos
- Laboratory of Proteomics of Non-Model Organisms, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Laidson Paes Gomes
- Laboratory of Proteomics of Non-Model Organisms, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Jean Armengaud
- Département Médicaments et Technologies pour la Santé, SPI, Université Paris-Saclay, CEA, INRAE, Bagnols-sur-Cèze, France
| | - Maria Miragaia
- Laboratory of Bacterial Evolution and Molecular Epidemiology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
- *Correspondence: Maria Miragaia,
| | - Ana Varela Coelho
- Laboratory of Proteomics of Non-Model Organisms, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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Abstract
SarA, a transcriptional regulator of Staphylococcus aureus, is a major global regulatory system that coordinates the expression of target genes involved in its pathogenicity. Various studies have identified a large number of SarA target genes, but an in-depth characterization of the sarA regulon, including small regulatory RNAs (sRNAs), has not yet been done. In this study, we utilized transcriptome sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq) to determine a comprehensive list of SarA-regulated targets, including both mRNAs and sRNAs. RNA-Seq analysis indicated 390 mRNAs and 51 sRNAs differentially expressed in a ΔsarA mutant, while ChIP-Seq revealed 354 mRNAs and 55 sRNA targets in the S. aureus genome. We confirmed the authenticity of several novel SarA targets by Northern blotting and electrophoretic mobility shift assays. Among them, we characterized repression of sprG2, a gene that encodes the toxin of a type I toxin-antitoxin system, indicating a multilayer lockdown of toxin expression by both SarA and its cognate antitoxin, SprF2. Finally, a novel SarA consensus DNA binding sequence was generated using the upstream promoter sequences of 15 novel SarA-regulated sRNA targets. A genome-wide scan with a deduced SarA motif enabled the discovery of new potential SarA target genes which were not identified in our RNA-Seq and ChIP-Seq analyses. The strength of this new consensus was confirmed with one predicted sRNA target. The RNA-Seq and ChIP-Seq combinatory analysis gives a snapshot of the regulation, whereas bioinformatic analysis reveals a permanent view of targets based on sequence. Altogether these experimental and in silico methodologies are effective to characterize transcriptional factor (TF) regulons and functions. IMPORTANCEStaphylococcus aureus, a commensal and opportunist pathogen, is responsible for a large number of human and animal infections, from benign to severe. Gene expression adaptation during infection requires a complex network of regulators, including transcriptional factors (TF) and sRNAs. TF SarA influences virulence, metabolism, biofilm formation, and resistance to some antibiotics. SarA directly regulates expression of around 20 mRNAs and a few sRNAs. Here, we combined high-throughput expression screening methods combined with binding assays and bioinformatics for an in-depth investigation of the SarA regulon. This combinatory approach allowed the identification of 85 unprecedented mRNAs and sRNAs targets, with at least 14 being primary. Among novel SarA direct targets, we characterized repression of sprG2, a gene that encodes the toxin of a toxin-antitoxin system, indicating a multilayer lockdown of toxin expression by both SarA and its cognate antitoxin, SprF2.
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Pizauro LJL, de Almeida CC, Silva SR, MacInnes JI, Kropinski AM, Zafalon LF, de Avila FA, de Mello Varani A. Genomic comparisons and phylogenetic analysis of mastitis-related staphylococci with a focus on adhesion, biofilm, and related regulatory genes. Sci Rep 2021; 11:17392. [PMID: 34462461 PMCID: PMC8405628 DOI: 10.1038/s41598-021-96842-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 08/10/2021] [Indexed: 02/07/2023] Open
Abstract
Mastitis is a common and costly disease on dairy farms, commonly caused by Staphylococcus spp. though the various species are associated with different clinical outcomes. In the current study, we performed genomic analyses to determine the prevalence of adhesion, biofilm, and related regulatory genes in 478 staphylococcal species isolated from clinical and subclinical mastitis cases deposited in public databases. The most prevalent adhesin genes (ebpS, atl, pls, sasH and sasF) were found in both clinical and subclinical isolates. However, the ebpS gene was absent in subclinical isolates of Staphylococcus arlettae, S. succinus, S. sciuri, S. equorun, S. galinarum, and S. saprophyticus. In contrast, the coa, eap, emp, efb, and vWbp genes were present more frequently in clinical (vs. subclincal) mastitis isolates and were highly correlated with the presence of the biofim operon (icaABCD) and its transcriptional regulator, icaR. Co-phylogenetic analyses suggested that many of these adhesins, biofilm, and associated regulatory genes could have been horizontally disseminated between clinical and subclinical isolates. Our results further suggest that several adhesins, biofilm, and related regulatory genes, which have been overlooked in previous studies, may be of use for virulence profiling of mastitis-related Staphylococcus strains or as potential targets for vaccine development.
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Affiliation(s)
- Lucas José Luduverio Pizauro
- grid.410543.70000 0001 2188 478XDepartment of Technology, Sao Paulo State University, Jaboticabal, Sao Paulo Brazil
| | - Camila Chioda de Almeida
- grid.410543.70000 0001 2188 478XDepartment of Microbiology, Sao Paulo State University, Jaboticabal, Sao Paulo Brazil
| | - Saura Rodrigues Silva
- grid.410543.70000 0001 2188 478XDepartment of Technology, Sao Paulo State University, Jaboticabal, Sao Paulo Brazil
| | - Janet I. MacInnes
- grid.34429.380000 0004 1936 8198Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON Canada
| | - Andrew M. Kropinski
- grid.34429.380000 0004 1936 8198Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON Canada
| | - Luiz Francisco Zafalon
- grid.460200.00000 0004 0541 873XBrazilian Agricultural Research Corporation (EMBRAPA), Embrapa Southeast Livestock, Sao Carlos, Sao Paulo Brazil
| | - Fernando Antônio de Avila
- grid.410543.70000 0001 2188 478XDepartment of Microbiology, Sao Paulo State University, Jaboticabal, Sao Paulo Brazil
| | - Alessandro de Mello Varani
- grid.410543.70000 0001 2188 478XDepartment of Technology, Sao Paulo State University, Jaboticabal, Sao Paulo Brazil
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10
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Schelin J, Cohn MT, Frisk B, Frees D. A Functional ClpXP Protease is Required for Induction of the Accessory Toxin Genes, tst, sed, and sec. Toxins (Basel) 2020; 12:E553. [PMID: 32872362 PMCID: PMC7551677 DOI: 10.3390/toxins12090553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/21/2020] [Accepted: 08/26/2020] [Indexed: 01/09/2023] Open
Abstract
Staphylococcal toxic shock syndrome is a potentially lethal illness attributed to superantigens produced by Staphylococcus aureus, in particular toxic shock syndrome toxin 1 (TSST-1), but staphylococcal enterotoxins (SEs) are also implicated. The genes encoding these important toxins are carried on mobile genetic elements, and the regulatory networks controlling expression of these toxins remain relatively unexplored. We show here that the highly conserved ClpXP protease stimulates transcription of tst (TSST-1), sec (SEC), and sed (SED) genes in the prototypical strains, SA564 and RN4282. In the wild-type cells, the post-exponential upregulation of toxin gene transcription was proposed to occur via RNAIII-mediated downregulation of the Rot repressor. Contradictive to this model, we showed that the post-exponential induction of tst, sed, and sec transcription did not occur in cells devoid of ClpXP activity, despite the Rot level being diminished. To identify transcriptional regulators with a changed expression in cells devoid of ClpXP activity, RNA sequencing was performed. The RNAseq analysis revealed a number of global virulence regulators that might act downstream of ClpXP, to control expression of tst and other virulence genes. Collectively, the results extend our understanding of the complex transcriptional regulation of the tst, sed, and sec genes.
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Affiliation(s)
- Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden; (J.S.); (B.F.)
| | - Marianne Thorup Cohn
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederikberg C, Denmark;
| | - Barbro Frisk
- Division of Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden; (J.S.); (B.F.)
| | - Dorte Frees
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederikberg C, Denmark;
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11
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Oelker A, Horger T, Kuttler C. From Staphylococcus aureus gene regulation to its pattern formation. J Math Biol 2019; 78:2207-2234. [PMID: 30949755 DOI: 10.1007/s00285-019-01340-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 12/31/2018] [Indexed: 11/25/2022]
Abstract
The focus of this paper is to develop a new partial differential equation model for the pattern formation of the human pathogen Staphylococcus aureus, starting from a newly developed model of selected gene regulation mechanisms. In our model, we do not only account for the bacteria densities and nutrient concentrations, but also for the quorum sensing and biofilm components, since they enable bacteria to coordinate their behavior and provide the environment in which the colony grows. To this end, we model the relevant gene regulation systems using ordinary differential equations and therefrom derive our evolution equations for quorum sensing and biofilm environment by time-scale arguments. Furthermore, we compare and validate our model and the corresponding simulation results with biological real data observations of Staphylococcus aureus mutant colony growth in the laboratory. We show that we are able to adequately display the qualitative biological features of pattern formation in selected mutants, using the parameter changes indicated by the gene regulation mechanisms.
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Affiliation(s)
- A Oelker
- Technische Universität München, Boltzmannstrasse 3, 85748, Garching bei München, Germany.
| | - T Horger
- Technische Universität München, Boltzmannstrasse 3, 85748, Garching bei München, Germany
| | - C Kuttler
- Technische Universität München, Boltzmannstrasse 3, 85748, Garching bei München, Germany
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12
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Transcriptional Regulation of icaADBC by both IcaR and TcaR in Staphylococcus epidermidis. J Bacteriol 2019; 201:JB.00524-18. [PMID: 30602488 DOI: 10.1128/jb.00524-18] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 12/17/2018] [Indexed: 12/17/2022] Open
Abstract
S. epidermidis is a primary cause of biofilm-mediated infections in humans due to adherence to foreign bodies. A major staphylococcal biofilm accumulation molecule is polysaccharide intracellular adhesin (PIA), which is synthesized by enzymes encoded by the icaADBC operon. Expression of PIA is highly variable among clinical isolates, suggesting that PIA expression levels are selected in certain niches of the host. However, the mechanisms that govern enhanced icaADBC transcription and PIA synthesis in these isolates are not known. We hypothesized that enhanced PIA synthesis in these isolates was due to function of IcaR and/or TcaR. Thus, two S. epidermidis isolates (1457 and CSF41498) with different icaADBC transcription and PIA expression levels were studied. Constitutive expression of both icaR and tcaR demonstrated that both repressors are functional and can completely repress icaADBC transcription in both 1457 and CSF41498. However, it was found that IcaR was the primary repressor for CSF41498 and TcaR was the primary repressor for 1457. Further analysis demonstrated that icaR transcription was repressed in 1457 in comparison to CSF41498, suggesting that TcaR functions as a repressor only in the absence of IcaR. Indeed, DNase I footprinting suggests IcaR and TcaR may bind to the same site within the icaR-icaA intergenic region. Lastly, we found mutants expressing variable amounts of PIA could rapidly be selected from both 1457 and CSF41498. Collectively, we propose that strains producing enhanced PIA synthesis are selected within certain niches of the host through several genetic mechanisms that function to repress icaR transcription, thus increasing PIA synthesis.IMPORTANCE Staphylococcus epidermidis is a commensal bacterium that resides on our skin. As a commensal, it protects humans from bacterial pathogens through a variety of mechanisms. However, it is also a significant cause of biofilm infections due to its ability to bind to plastic. Polysaccharide intercellular adhesin is a significant component of biofilm, and we propose that the expression of this polysaccharide is beneficial in certain host niches, such as providing extra strength when the bacterium is colonizing the lumen of a catheter, and detrimental in others, such as colonization of the skin surface. We show here that fine-tuning of icaADBC transcription, and thus PIA synthesis, is mediated via two transcriptional repressors, IcaR and TcaR.
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13
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Chemmugil P, Lakshmi P, Annamalai A. Exploring Morin as an anti-quorum sensing agent (anti-QSA) against resistant strains of Staphylococcus aureus. Microb Pathog 2019; 127:304-315. [DOI: 10.1016/j.micpath.2018.12.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 09/28/2018] [Accepted: 12/04/2018] [Indexed: 11/30/2022]
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14
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Small RNA teg49 Is Derived from a sarA Transcript and Regulates Virulence Genes Independent of SarA in Staphylococcus aureus. Infect Immun 2018; 86:IAI.00635-17. [PMID: 29133345 DOI: 10.1128/iai.00635-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Accepted: 10/30/2017] [Indexed: 01/08/2023] Open
Abstract
Expression of virulence factors in Staphylococcus aureus is regulated by a wide range of transcriptional regulators, including proteins and small RNAs (sRNAs), at the level of transcription and/or translation. The sarA locus consists of three overlapping transcripts generated from three distinct promoters, all containing the sarA open reading frame (ORF). The 5' untranslated regions (UTRs) of these transcripts contain three separate regions ∼711, 409, and 146 nucleotides (nt) upstream of the sarA translation start, the functions of which remain unknown. Recent transcriptome-sequencing (RNA-Seq) analysis and subsequent characterization indicated that two sRNAs, teg49 and teg48, are processed and likely produced from the sarA P3 and sarA P1 transcripts of the sarA locus, respectively. In this report, we utilized a variety of sarA promoter mutants and cshA and rnc mutants to ascertain the contributions of these factors to the generation of teg49. We also defined the transcriptional regulon of teg49, including virulence genes not regulated by SarA. Phenotypically, teg49 did not impact biofilm formation or affect overall SarA expression significantly. Comparative analyses of RNA-Seq data between the wild-type, teg49 mutant, and sarA mutant strains indicated that ∼133 genes are significantly upregulated while 97 are downregulated in a teg49 deletion mutant in a sarA-independent manner. An abscess model of skin infection indicated that the teg49 mutant exhibited a reduced bacterial load compared to the wild-type S. aureus Overall, these results suggest that teg49 sRNA has a regulatory role in target gene regulation independent of SarA. The exact mechanism of this regulation is yet to be dissected.
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15
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Peng H, Zhang Y, Palmer LD, Kehl-Fie TE, Skaar EP, Trinidad JC, Giedroc DP. Hydrogen Sulfide and Reactive Sulfur Species Impact Proteome S-Sulfhydration and Global Virulence Regulation in Staphylococcus aureus. ACS Infect Dis 2017; 3:744-755. [PMID: 28850209 DOI: 10.1021/acsinfecdis.7b00090] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hydrogen sulfide (H2S) is thought to protect bacteria from oxidative stress, but a comprehensive understanding of its function in bacteria is largely unexplored. In this study, we show that the human pathogen Staphylococcus aureus (S. aureus) harbors significant effector molecules of H2S signaling, reactive sulfur species (RSS), as low molecular weight persulfides of bacillithiol, coenzyme A, and cysteine, and significant inorganic polysulfide species. We find that proteome S-sulfhydration, a post-translational modification (PTM) in H2S signaling, is widespread in S. aureus. RSS levels modulate the expression of secreted virulence factors and the cytotoxicity of the secretome, consistent with an S-sulfhydration-dependent inhibition of DNA binding by MgrA, a global virulence regulator. Two previously uncharacterized thioredoxin-like proteins, denoted TrxP and TrxQ, are S-sulfhydrated in sulfide-stressed cells and are capable of reducing protein hydrodisulfides, suggesting that this PTM is potentially regulatory in S. aureus. In conclusion, our results reveal that S. aureus harbors a pool of proteome- and metabolite-derived RSS capable of impacting protein activities and gene regulation and that H2S signaling can be sensed by global regulators to affect the expression of virulence factors.
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Affiliation(s)
- Hui Peng
- Department of Chemistry, Indiana University, 800 E. Kirkwood Drive, Bloomington, Indiana 47405-7102, United States
- Graduate Program in Biochemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, Indiana 47405, United States
| | - Yixiang Zhang
- Department of Chemistry, Indiana University, 800 E. Kirkwood Drive, Bloomington, Indiana 47405-7102, United States
- Laboratory for Biological Mass Spectrometry,
Department of Chemistry, Indiana University, Simon Hall 120B, 212 S. Hawthorne
Drive, Bloomington, Indiana 47405, United States
| | - Lauren D. Palmer
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, Tennessee 37232-2363, United States
| | - Thomas E. Kehl-Fie
- Department of Microbiology, University of Illinois Urbana−Champaign, 601 South Goodwin Avenue, Urbana, Illinois 61801, United States
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, Tennessee 37232-2363, United States
| | - Jonathan C. Trinidad
- Department of Chemistry, Indiana University, 800 E. Kirkwood Drive, Bloomington, Indiana 47405-7102, United States
- Laboratory for Biological Mass Spectrometry,
Department of Chemistry, Indiana University, Simon Hall 120B, 212 S. Hawthorne
Drive, Bloomington, Indiana 47405, United States
| | - David P. Giedroc
- Department of Chemistry, Indiana University, 800 E. Kirkwood Drive, Bloomington, Indiana 47405-7102, United States
- Department
of Molecular and Cellular Biochemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, Indiana 47405, United States
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16
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Ma R, Qiu S, Jiang Q, Sun H, Xue T, Cai G, Sun B. AI-2 quorum sensing negatively regulates rbf expression and biofilm formation in Staphylococcus aureus. Int J Med Microbiol 2017; 307:257-267. [PMID: 28416278 DOI: 10.1016/j.ijmm.2017.03.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Indexed: 12/11/2022] Open
Abstract
Staphylococcus aureus is an important pathogen that is capable of forming biofilms on biomaterial surfaces to cause biofilm-associated infections. Autoinducer 2 (AI-2), a universal language for interspecies communication, is involved in a variety of physiological activities, although its exact role in Gram-positive bacteria, especially in S. aureus, is not yet thoroughly characterized. Herein we demonstrate that inactivation of luxS, which encodes AI-2 synthase, resulted in increased biofilm formation and higher polysaccharide intercellular adhesion (PIA) production compared with the wild-type strain in S. aureus NCTC8325. The transcript level of rbf, a positive regulator of biofilm formation, was significantly increased in the luxS mutant. All of the parental phenotypes could be restored by genetic complementation and chemically synthesized 4,5-dihydroxy-2,3-pentanedione, the AI-2 precursor molecule, suggesting that AI-2 has a signaling function to regulate rbf transcription and biofilm formation in S. aureus. Phenotypic analysis revealed that the luxS rbf double mutant produced approximately the same amount of biofilms and PIA as the rbf mutant. In addition, real-time quantitative reverse transcription-PCR analysis showed that the icaA transcript level of the rbf mutant was similar to that of the luxS rbf double mutant. These findings demonstrate that the LuxS/AI-2 system regulates PIA-dependent biofilm formation via repression of rbf expression in S. aureus. Furthermore, we demonstrated that Rbf could bind to the sarX and rbf promoters to upregulate their expression.
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Affiliation(s)
- Ronghua Ma
- CAS Key Laboratory of Innate Immunity and Chronic Disease, University of Science and Technology of China, Hefei, Anhui 230027, China; School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Shuwan Qiu
- School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Qiu Jiang
- CAS Key Laboratory of Innate Immunity and Chronic Disease, University of Science and Technology of China, Hefei, Anhui 230027, China; School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Haipeng Sun
- CAS Key Laboratory of Innate Immunity and Chronic Disease, University of Science and Technology of China, Hefei, Anhui 230027, China; School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Ting Xue
- School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Gang Cai
- School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China; Hefei National Laboratory for Physical Sciences at Microscale, Hefei, Anhui 230027, China.
| | - Baolin Sun
- CAS Key Laboratory of Innate Immunity and Chronic Disease, University of Science and Technology of China, Hefei, Anhui 230027, China; School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, Anhui 230027, China; Hefei National Laboratory for Physical Sciences at Microscale, Hefei, Anhui 230027, China.
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17
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RNAIII of the Staphylococcus aureus agr system activates global regulator MgrA by stabilizing mRNA. Proc Natl Acad Sci U S A 2015; 112:14036-41. [PMID: 26504242 DOI: 10.1073/pnas.1509251112] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
RNAIII, the effector of the agr quorum-sensing system, plays a key role in virulence gene regulation in Staphylococcus aureus, but how RNAIII transcriptionally regulates its downstream genes is not completely understood. Here, we show that RNAIII stabilizes mgrA mRNA, thereby increasing the production of MgrA, a global transcriptional regulator that affects the expression of many genes. The mgrA gene is transcribed from two promoters, P1 and P2, to produce two mRNA transcripts with long 5' UTR. Two adjacent regions of the mgrA mRNA UTR transcribed from the upstream P2 promoter, but not the P1 promoter, form a stable complex with two regions of RNAIII near the 5' and 3' ends. We further demonstrate that the interaction has several biological effects. We propose that MgrA can serve as an intermediary regulator through which agr exerts its regulatory function.
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18
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Arya R, Princy SA. Exploration of Modulated Genetic Circuits Governing Virulence Determinants in Staphylococcus aureus. Indian J Microbiol 2015; 56:19-27. [PMID: 26843693 DOI: 10.1007/s12088-015-0555-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/15/2015] [Indexed: 02/06/2023] Open
Abstract
The expression of virulence genes in the human pathogen Staphylococcus aureus is strongly influenced by the multiple global regulators. The signal transduction cascade of these global regulators is accountable for recognizing and integrating the environmental cues to regulate the virulence regulon. While the production of virulent factors by individual global regulators are comparatively straightforward to define, auto-regulation of these global regulators and their impact on other regulators is more complex process. There are several reports on the production of virulent factors that are precisely regulated by switching processes of multiple global regulators including some prominent accessory regulators such as agr, sae and sar which allows S. aureus to coordinate the gene expression, and thus, provide organism an ability to act collectively. This review implicates the mechanisms involved in the global regulation of various virulence factors along with a comprehensive discussion on the differences between these signal transduction systems, their auto-induction and, coordination of classical and some comparatively new bacterial signal transduction systems.
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Affiliation(s)
- Rekha Arya
- Quorum Sensing Laboratory, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA University, Thirumalaisamudram, Thanjavur, 613 401 Tamil Nadu India
| | - S Adline Princy
- Quorum Sensing Laboratory, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA University, Thirumalaisamudram, Thanjavur, 613 401 Tamil Nadu India
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19
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Andrey DO, Jousselin A, Villanueva M, Renzoni A, Monod A, Barras C, Rodriguez N, Kelley WL. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus. PLoS One 2015; 10:e0135579. [PMID: 26275216 PMCID: PMC4537247 DOI: 10.1371/journal.pone.0135579] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 07/24/2015] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression.
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Affiliation(s)
- Diego O. Andrey
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland
| | - Ambre Jousselin
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
| | - Maite Villanueva
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
| | - Adriana Renzoni
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland
| | - Antoinette Monod
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland
| | - Christine Barras
- Service of Infectious Diseases, University Hospital and Medical School of Geneva, 4 rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland
| | - Natalia Rodriguez
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
| | - William L. Kelley
- Department of Microbiology and Molecular Medicine, University Hospital and Medical School of Geneva, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
- * E-mail:
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20
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Mahapa A, Mandal S, Biswas A, Jana B, Polley S, Sau S, Sau K. Chemical and thermal unfolding of a global staphylococcal virulence regulator with a flexible C-terminal end. PLoS One 2015; 10:e0122168. [PMID: 25822635 PMCID: PMC4379015 DOI: 10.1371/journal.pone.0122168] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 02/07/2015] [Indexed: 11/19/2022] Open
Abstract
SarA, a Staphylococcus aureus-specific dimeric protein, modulates the expression of numerous proteins including various virulence factors. Interestingly, S. aureus synthesizes multiple SarA paralogs seemingly for optimizing the expression of its virulence factors. To understand the domain structure/flexibility and the folding/unfolding mechanism of the SarA protein family, we have studied a recombinant SarA (designated rSarA) using various in vitro probes. Limited proteolysis of rSarA and the subsequent analysis of the resulting protein fragments suggested it to be a single-domain protein with a long, flexible C-terminal end. rSarA was unfolded by different mechanisms in the presence of different chemical and physical denaturants. While urea-induced unfolding of rSarA occurred successively via the formation of a dimeric and a monomeric intermediate, GdnCl-induced unfolding of this protein proceeded through the production of two dimeric intermediates. The surface hydrophobicity and the structures of the intermediates were not identical and also differed significantly from those of native rSarA. Of the intermediates, the GdnCl-generated intermediates not only possessed a molten globule-like structure but also exhibited resistance to dissociation during their unfolding. Compared to the native rSarA, the intermediate that was originated at lower GdnCl concentration carried a compact shape, whereas, other intermediates owned a swelled shape. The chemical-induced unfolding, unlike thermal unfolding of rSarA, was completely reversible in nature.
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Affiliation(s)
- Avisek Mahapa
- Department of Biotechnology, Haldia Institute of Technology, Haldia, West Bengal, India
| | - Sukhendu Mandal
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
| | - Anindya Biswas
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
| | - Biswanath Jana
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
| | - Soumitra Polley
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
| | - Subrata Sau
- Department of Biochemistry, Bose Institute, Kolkata, West Bengal, India
- * E-mail: (SS); (KS)
| | - Keya Sau
- Department of Biotechnology, Haldia Institute of Technology, Haldia, West Bengal, India
- * E-mail: (SS); (KS)
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21
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Nitzan M, Fechter P, Peer A, Altuvia Y, Bronesky D, Vandenesch F, Romby P, Biham O, Margalit H. A defense-offense multi-layered regulatory switch in a pathogenic bacterium. Nucleic Acids Res 2015; 43:1357-69. [PMID: 25628364 PMCID: PMC4330369 DOI: 10.1093/nar/gkv001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells adapt to environmental changes by efficiently adjusting gene expression programs. Staphylococcus aureus, an opportunistic pathogenic bacterium, switches between defensive and offensive modes in response to quorum sensing signal. We identified and studied the structural characteristics and dynamic properties of the core regulatory circuit governing this switch by deterministic and stochastic computational methods, as well as experimentally. This module, termed here Double Selector Switch (DSS), comprises the RNA regulator RNAIII and the transcription factor Rot, defining a double-layered switch involving both transcriptional and post-transcriptional regulations. It coordinates the inverse expression of two sets of target genes, immuno-modulators and exotoxins, expressed during the defensive and offensive modes, respectively. Our computational and experimental analyses show that the DSS guarantees fine-tuned coordination of the inverse expression of its two gene sets, tight regulation, and filtering of noisy signals. We also identified variants of this circuit in other bacterial systems, suggesting it is used as a molecular switch in various cellular contexts and offering its use as a template for an effective switching device in synthetic biology studies.
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Affiliation(s)
- Mor Nitzan
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
| | - Pierre Fechter
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg F-67084, France
| | - Asaf Peer
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
| | - Yael Altuvia
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
| | - Delphine Bronesky
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg F-67084, France
| | - François Vandenesch
- CIRI, International Center for Infectiology Research,Lyon, France Inserm, U1111, Lyon, France École Normale Supérieure de Lyon, Lyon, France Université Lyon 1, Lyon, France CNRS, UMR5308, Lyon, France
| | - Pascale Romby
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg F-67084, France
| | - Ofer Biham
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
| | - Hanah Margalit
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
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22
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Contribution of teg49 small RNA in the 5' upstream transcriptional region of sarA to virulence in Staphylococcus aureus. Infect Immun 2014; 82:4369-79. [PMID: 25092913 DOI: 10.1128/iai.02002-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
High-throughput RNA sequencing technology has found the 5' untranslated region of sarA to contain two putative small RNAs (sRNAs), designated teg49 and teg48. Northern blot analysis disclosed that teg49 and teg48 were detectable within the P3-P1 and P1 sarA promoter regions, respectively. Focusing on teg49, we found that this sRNA, consisting of 196 nucleotides, is transcribed in the same direction as the sarA P3 transcript. The expression of both P3 and teg49 transcripts is dependent on sigB and cshA, which encodes a DEAD box RNA helicase. Within the sRNA teg49, there are two putative hairpin-loop structures, HP1 and HP2. Transversion mutation of the HP1 loop produced a smaller amount of sarA P3 and P2 transcripts and SarA protein than the corresponding HP1 stem and the HP2 stem and loop mutations, leading to lower RNAII transcription and derepression of aur transcription. The HP1 loop mutant also exhibited less biofilm formation than the parental and complemented strains. Complementation with shuttle plasmid pEPSA5 carrying teg49 was able to reestablish sarA P3 and P2 transcription and augment RNAII expression in the HP1 loop mutant. We thus conclude that teg49, embedded within the extended promoter regions of sarA, is modulated by sigB and cshA and plays an important trans-acting role in modulating the transcription and ensuing expression of sarA.
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Liu CL, Chen ZJ, Wang F, Hou HY, Wang Y, Zhu XH, Jian C, Tian L, Yan SZ, Xu LQ, Sun ZY. The impact of mgrA on progression of Staphylococcus aureus sepsis. Microb Pathog 2014; 71-72:56-61. [DOI: 10.1016/j.micpath.2014.03.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/30/2014] [Accepted: 03/31/2014] [Indexed: 12/27/2022]
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Romilly C, Lays C, Tomasini A, Caldelari I, Benito Y, Hammann P, Geissmann T, Boisset S, Romby P, Vandenesch F. A non-coding RNA promotes bacterial persistence and decreases virulence by regulating a regulator in Staphylococcus aureus. PLoS Pathog 2014; 10:e1003979. [PMID: 24651379 PMCID: PMC3961350 DOI: 10.1371/journal.ppat.1003979] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 01/21/2014] [Indexed: 11/19/2022] Open
Abstract
Staphylococcus aureus produces a high number of RNAs for which the functions are poorly understood. Several non-coding RNAs carry a C-rich sequence suggesting that they regulate mRNAs at the post-transcriptional level. We demonstrate that the Sigma B-dependent RsaA RNA represses the synthesis of the global transcriptional regulator MgrA by forming an imperfect duplex with the Shine and Dalgarno sequence and a loop-loop interaction within the coding region of the target mRNA. These two recognition sites are required for translation repression. Consequently, RsaA causes enhanced production of biofilm and a decreased synthesis of capsule formation in several strain backgrounds. These phenotypes led to a decreased protection of S. aureus against opsonophagocytic killing by polymorphonuclear leukocytes compared to the mutant strains lacking RsaA. Mice animal models showed that RsaA attenuates the severity of acute systemic infections and enhances chronic catheter infection. RsaA takes part in a regulatory network that contributes to the complex interactions of S. aureus with the host immune system to moderate invasiveness and favour chronic infections. It is the first example of a conserved small RNA in S. aureus functioning as a virulence suppressor of acute infections. Because S. aureus is essentially a human commensal, we propose that RsaA has been positively selected through evolution to support commensalism and saprophytic interactions with the host. Staphylococcus aureus is a commensal and an opportunistic pathogen that causes a large range of community and hospital-acquired infections. The bacteria produce an array of virulence factors, the expression of which is regulated by a set of regulators including proteins and RNAs. In recent years, a large number of small non-coding RNAs encoded by the S. aureus genome have been identified but determination of their function is still lagging behind. This study shows that RsaA, a staphylococcal conserved non-coding RNA, operates at the post-transcriptional level by repressing the translation of the master regulatory protein MgrA. The repression is based on a direct interaction of RsaA with the ribosome binding site of mgrA mRNA. Through MgrA regulation, RsaA activates biofilm formation and inhibits capsule synthesis. Using appropriate animal models, we showed that RsaA acts as a suppressor of virulence because the deletion of its gene increases the invasiveness of S. aureus in the mice sepsis model. RsaA is thus part of complex regulatory network that modify the interactions of S. aureus with the eukaryotic immune system. These findings illustrate how small RNAs can have a major impact in bacterial biology.
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Affiliation(s)
- Cédric Romilly
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Claire Lays
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
| | - Arnaud Tomasini
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Isabelle Caldelari
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Yvonne Benito
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
- Hospices Civils de Lyon, Lyon, France
| | | | - Thomas Geissmann
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
| | - Sandrine Boisset
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
- Hospices Civils de Lyon, Lyon, France
| | - Pascale Romby
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
- * E-mail: (PR); (FV)
| | - François Vandenesch
- CIRI, International Center for Infectiology Research, Université de Lyon, Lyon, France
- Inserm U1111, Lyon, France
- Ecole Normale Supérieure de Lyon, Lyon, France
- Université Lyon 1, Lyon, France
- CNRS, UMR5308, Lyon, France
- Hospices Civils de Lyon, Lyon, France
- * E-mail: (PR); (FV)
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25
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Regulation of expression of abcA and its response to environmental conditions. J Bacteriol 2014; 196:1532-9. [PMID: 24509312 DOI: 10.1128/jb.01406-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The ATP-dependent transporter gene abcA in Staphylococcus aureus confers resistance to hydrophobic β-lactams. In strain ISP794, abcA is regulated by the transcriptional regulators MgrA and NorG and shares a 420-nucleotide intercistronic region with the divergently transcribed pbp4 gene, which encodes the transpeptidase Pbp4. Exposure of exponentially growing cells to iron-limited media, oxidative stress, and acidic pH (5.5) for 0.5 to 2 h had no effect on abcA expression. In contrast, nutrient limitation produced a significant increase in abcA transcripts. We identified three additional regulators (SarA, SarZ, and Rot) that bind to the overlapping promoter region of abcA and pbp4 in strain MW2 and investigated their role in the regulation of abcA expression. Expression of abcA is decreased by 10.0-fold in vivo in a subcutaneous abscess model. In vitro, abcA expression depends on rot and sarZ regulators. Moenomycin A exposure of strain MW2 produced an increase in abcA transcripts. Relative to MW2, the MIC of moenomycin was decreased 8-fold for MW2ΔabcA and increased 10-fold for the MW2 abcA overexpresser, suggesting that moenomycin is a substrate of AbcA.
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Manna AC. Genetic interruption of target genes for investigation of virulence factors. Methods Mol Biol 2014; 1085:149-167. [PMID: 24085695 DOI: 10.1007/978-1-62703-664-1_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Recently, more emphasis has been given to understand molecular genetics and the contribution of a gene in the disease process. In fact, increased understanding of bacterial pathogenesis and intracellular communication has revealed many potential strategies for development of novel agents to treat bacterial infection. Therefore, to study the function and the involvement of a particular gene in pathogenesis, the inactivation or interruption is very important. In this section, various methods leading to inactivation of the gene in Staphylococcus aureus will be discussed.
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Affiliation(s)
- Adhar C Manna
- Department of Biological Sciences, Presidency University, Kolkata, WB, India
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Arya R, Princy SA. An insight into pleiotropic regulators Agr and Sar: molecular probes paving the new way for antivirulent therapy. Future Microbiol 2013; 8:1339-53. [DOI: 10.2217/fmb.13.92] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Staphylococcus aureus pathogenesis is an intricate process involving a diverse array of extracellular proteins, biofilm and cell wall components that are coordinately expressed in different stages of infection. The expression of two divergent loci, agr and sar, is increasingly recognized as a key regulator of virulence in S. aureus, and there is mounting evidence for the role of these loci in staphylococcal infections. The functional agr regulon is critical for the production of virulence factors, including α, β and δ hemolysins. The sar locus encodes SarA protein, which regulates the expression of cell wall-associated and certain extracellular proteins in agr-dependent and agr-independent pathways. Multidrug-resistant S. aureus is a leading cause of morbidity and mortality in the world and its management, especially in community-acquired methicillin-resistant S. aureus infections, has evolved comparatively little. In particular, no novel targets have been incorporated into its treatment to date. Hence, these loci appear to be the most significant and are currently at the attention of intense investigation regarding their therapeutic prospects.
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Affiliation(s)
- Rekha Arya
- Quorum Sensing Laboratory, SASTRA‘s Hub for Research & Innovation (SHRI), School of Chemical & Biotechnology, SASTRA University, Tirumalaisamudrum 613401, Thanjavur, Tamil Nadu, India
| | - S Adline Princy
- Quorum Sensing Laboratory, SASTRA‘s Hub for Research & Innovation (SHRI), School of Chemical & Biotechnology, SASTRA University, Tirumalaisamudrum 613401, Thanjavur, Tamil Nadu, India
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Genetic variation in the Staphylococcus aureus 8325 strain lineage revealed by whole-genome sequencing. PLoS One 2013; 8:e77122. [PMID: 24098817 PMCID: PMC3786944 DOI: 10.1371/journal.pone.0077122] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 09/05/2013] [Indexed: 01/05/2023] Open
Abstract
Staphylococcus aureus strains of the 8325 lineage, especially 8325-4 and derivatives lacking prophage, have been used extensively for decades of research. We report herein the results of our deep sequence analysis of strain 8325-4. Assignment of sequence variants compared with the reference strain 8325 (NRS77/PS47) required correction of errors in the 8325 reference genome, and reassessment of variation previously attributed to chemical mutagenesis of the restriction-defective RN4220. Using an extensive strain pedigree analysis, we discovered that 8325-4 contains 16 single nucleotide polymorphisms (SNP) arising prior to the construction of RN4220. We identified 5 indels in 8325-4 compared with 8325. Three indels correspond to expected Φ11, 12, 13 excisions, one indel is explained by a sequence assembly artifact, and the final indel (Δ63bp) in the spa-sarS intergenic region is common to only a sub-lineage of 8325-4 strains including SH1000. This deletion was found to significantly decrease (75%) steady state sarS but not spa transcript levels in post-exponential phase. The sub-lineage 8325-4 was also found to harbor 4 additional SNPs. We also found large sequence variation between 8325, 8325-4 and RN4220 in a cluster of repetitive hypothetical proteins (SA0282 homologs) near the Ess secretion cluster. The overall 8325-4 SNP set results in 17 alterations within coding sequences. Remarkably, we discovered that all tested strains of the 8325-4 lineage lack phenol soluble modulin α3 (PSMα3), a virulence determinant implicated in neutrophil chemotaxis, biofilm architecture and surface spreading. Collectively, our results clarify and define the 8325-4 pedigree and reveal clear evidence that mutations existing throughout all branches of this lineage, including the widely used RN6390 and SH1000 strains, could conceivably impact virulence regulation.
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Ibarra JA, Pérez-Rueda E, Carroll RK, Shaw LN. Global analysis of transcriptional regulators in Staphylococcus aureus. BMC Genomics 2013; 14:126. [PMID: 23442205 PMCID: PMC3616918 DOI: 10.1186/1471-2164-14-126] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 02/12/2013] [Indexed: 02/01/2023] Open
Abstract
Background Staphylococcus aureus is a widely distributed human pathogen capable of infecting almost every ecological niche of the host. As a result, it is responsible for causing many different diseases. S. aureus has a vast array of virulence determinants whose expression is modulated by an intricate regulatory network, where transcriptional factors (TFs) are the primary elements. In this work, using diverse sequence analysis, we evaluated the repertoire of TFs and sigma factors in the community-associated methicillin resistant S. aureus (CA-MRSA) strain USA300-FPR3757. Results A total of 135 TFs and sigma factors were identified and classified into 36 regulatory families. From these around 43% have been experimentally characterized to date, which demonstrates the significant work still at hand to unravel the regulatory network in place for this important pathogen. A comparison of the TF repertoire of S. aureus against 1209 sequenced bacterial genomes was carried out allowing us to identify a core set of orthologous TFs for the Staphylococacceae, and also allowing us to assign potential functions to previously uncharacterized TFs. Finally, the USA300 TFs were compared to those in eleven other S. aureus strains including: Newman, COL, JH1, JH9, MW2, Mu3, Mu50, N315, RF122, MRSA252 and MSSA476. We identify conserved TFs among these strains and suggest possible regulatory interactions. Conclusions The analysis presented herein highlights the complexity of regulatory networks in S. aureus strains, identifies key conserved TFs among the Staphylococacceae, and offers unique insights into several as yet uncharacterized TFs.
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Affiliation(s)
- Jose Antonio Ibarra
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 East Fowler Avenue, ISA 2015, Tampa, FL 33620-5150, USA.
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31
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Junecko JM, Zielinska AK, Mrak LN, Ryan DC, Graham JW, Smeltzer MS, Lee CY. Transcribing virulence in Staphylococcus aureus. World J Clin Infect Dis 2012; 2:63-76. [DOI: 10.5495/wjcid.v2.i4.63] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is an important human pathogen capable of causing a diverse range of infections. Once regarded as an opportunistic pathogen causing primarily nosocomial infections, recent years have seen the emergence of S. aureus strains capable of causing serious infection even in otherwise healthy human hosts. There has been much debate about whether this transition is a function of unique genotypic characteristics or differences in the expression of conserved virulence factors, but irrespective of this debate it is clear that the ability of S. aureus to cause infection in all of its diverse forms is heavily influenced by its ability to modulate gene expression in response to changing conditions within the human host. Indeed, the S. aureus genome encodes more than 100 transcriptional regulators that modulate the production of virulence factors either directly via interactions with cis elements associated with genes encoding virulence factors or indirectly through their complex interactions with each other. The goal of this review is to summarize recent work describing these regulators and their contribution to defining S. aureus as a human pathogen.
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32
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Arya R, Princy SA. Computational approach to design small molecule inhibitors and identify SarA as a potential therapeutic candidate. Med Chem Res 2012. [DOI: 10.1007/s00044-012-0185-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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33
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Biofilm formation in Staphylococcus implant infections. A review of molecular mechanisms and implications for biofilm-resistant materials. Biomaterials 2012; 33:5967-82. [PMID: 22695065 DOI: 10.1016/j.biomaterials.2012.05.031] [Citation(s) in RCA: 698] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 05/15/2012] [Indexed: 02/07/2023]
Abstract
Implant infections in orthopaedics, as well as in many other medical fields, are chiefly caused by staphylococci. The ability of growing within a biofilm enhances the chances of staphylococci to protect themselves from host defences, antibiotic therapies, and biocides. Advances in scientific knowledge on structural molecules (exopolysaccharide, proteins, teichoic acids, and the most recently described extracellular DNA), on the synthesis and genetics of staphylococcal biofilms, and on the complex network of signal factors that intervene in their control are here presented, also reporting on the emerging strategies to disrupt or inhibit them. The attitude of polymorphonuclear neutrophils and macrophages to infiltrate and phagocytise biofilms, as well as the ambiguous behaviour exhibited by these innate immune cells in biofilm-related implant infections, are here discussed. Research on anti-biofilm biomaterials is focused, reviewing materials loaded with antibacterial substances, or coated with anti-adhesive/anti-bacterial immobilized agents, or surfaced with nanostructures. Latter approaches appear promising, since they avoid the spread of antibacterial substances in the neighbouring tissues with the consequent risk of inducing bacterial resistance.
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Cue D, Lei MG, Lee CY. Genetic regulation of the intercellular adhesion locus in staphylococci. Front Cell Infect Microbiol 2012; 2:38. [PMID: 23061050 PMCID: PMC3459252 DOI: 10.3389/fcimb.2012.00038] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 03/05/2012] [Indexed: 01/29/2023] Open
Abstract
The formation of biofilms by Staphylococcus aureus and Staphylococcus epidermidis is an important aspect of many staphylococcal infections, most notably endocarditis, osteomyelitis and infections associated with indwelling medical devices. The major constituents of staphylococcal biofilms are polysaccharides, such as poly N-acetyl glucosamine (PIA/PNAG), cell surface and secreted bacterial proteins, and extracellular DNA. The exact composition of biofilms often varies considerably between different strains of staphylococci and between different sites of infection by the same strain. PIA/PNAG is synthesized by the products of four genes, icaADBC, that are encoded in a single operon. A fifth gene, icaR, is a negative regulator of icaADBC. Expression of icaADBC is tightly regulated, but can often be induced in vitro by growing staphylococci in the presence of high salt, high glucose, or ethanol. Regulation of icaADBC is complex and numerous regulatory factors have been implicated in control of icaADBC. Many of these are well known global transcriptional regulatory factors like SarA and sigmaB, whereas other regulators, such as IcaR, seem to affect expression of relatively few genes. Here, we will summarize how various regulatory factors affect the production of PIA/PNAG in staphylococci.
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Affiliation(s)
- David Cue
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock AR, USA
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35
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Reduced aeration affects the expression of the NorB efflux pump of Staphylococcus aureus by posttranslational modification of MgrA. J Bacteriol 2012; 194:1823-34. [PMID: 22287526 DOI: 10.1128/jb.06503-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously showed that at acid pH, the transcription of norB, encoding the NorB efflux pump, increases due to a reduction in the phosphorylation level of MgrA, which in turn leads to a reduction in bacterial killing by moxifloxacin, a substrate of the NorB efflux pump. In this study, we demonstrated that reduced oxygen levels did not affect the transcript levels of mgrA but modified the dimerization of the MgrA protein, which remained mostly in its monomeric form. Under reduced aeration, we also observed a 21.7-fold increase in the norB transcript levels after 60 min of growth that contributed to a 4-fold increase in the MICs of moxifloxacin and sparfloxacin for Staphylococcus aureus RN6390. The relative proportions of MgrA in monomeric and dimeric forms were altered by treatment with H(2)O(2), but incubation of purified MgrA with extracts of cells grown under reduced but not normal aeration prevented MgrA from being converted to its dimeric DNA-binding form. This modification was associated with cleavage of a fragment of the dimerization domain of MgrA without change in MgrA phosphorylation and an increase in transcript levels of genes encoding serine proteases in cells incubated at reduced aeration. Taken together, these data suggest that modification of MgrA by proteases underlies the reversal of its repression of norB and increased resistance to NorB substrates in response to reduced-aeration conditions, illustrating a third mechanism of posttranslational modification, in addition to oxidation and phosphorylation, that modulates the regulatory activities of MgrA.
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36
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Transcriptional profiling analysis of the global regulator NorG, a GntR-like protein of Staphylococcus aureus. J Bacteriol 2011; 193:6207-14. [PMID: 21908673 DOI: 10.1128/jb.05847-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The GntR-like protein NorG has been shown to affect Staphylococcus aureus genes involved in resistance to quinolones and β-lactams, such as those encoding the NorB and AbcA transporters. To identify the target genes regulated by NorG, we carried out transcriptional-profiling assays using S. aureus RN6390 and its isogenic norG::cat mutant. Our data showed that NorG positively affected the transcription of global regulators mgrA, arlS, and sarZ. The three putative drug efflux pump genes most positively affected by NorG were the NorB efflux pump (5.1-fold), the MmpL-like protein SACOL2566 (5.2-fold), and the BcrA-like drug transporter SACOL2525 (5.7-fold) genes. The S. aureus predicted MmpL protein showed 53% homology with the MmpL lipid transporter of Mycobacterium tuberculosis, and the putative SACOL2525 protein showed 87% homology with the bacitracin drug transporter BcrA of Staphylococcus hominis. Two pump genes most negatively affected by NorG were the NorC (4-fold) and AbcA (6-fold) genes. Other categories of genes, such as those participating in amino acid, inorganic ion, or nucleotide transporters and metabolism, were also affected by NorG. Real-time reverse transcription (RT)-PCR assays for mgrA, arlS, sarZ, norB, norC, abcA, mmpL, and bcrA-like were carried out to verify microarray data and showed the same level of up- or downregulation by NorG. The norG mutant showed a 2-fold increase in resistance to norfloxacin and rhodamine, both substrates of the NorC transporter, which is consistent with the resistance phenotype conferred by overexpression of norC on a plasmid. These data indicate that NorG has broad regulatory function in S. aureus.
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Implication of the NorB efflux pump in the adaptation of Staphylococcus aureus to growth at acid pH and in resistance to moxifloxacin. Antimicrob Agents Chemother 2011; 55:3214-9. [PMID: 21555767 DOI: 10.1128/aac.00289-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is an important pathogen that adapts and survives in low-pH environments. One component of this adaptation involves the regulation of genes encoding bacterial transporters that could affect response to antibiotics under these conditions. We previously demonstrated that the transcriptional regulator MgrA in its phosphorylated form (MgrA-P) represses the expression of norB, encoding the NorB multidrug resistance efflux pump. In this study, we focused on changes in the expression of mgrA at the transcriptional and posttranslational levels, following a shift from pH 7.0 to pH 4.5. We then correlated those changes with modifications in transcript levels of norB and to resistance to moxifloxacin, a substrate of NorB. At pH 4.5, S. aureus MgrA increased 2-fold and MgrA-P decreased 4-fold, associated with an 8-fold increase in norB transcripts and a 6-fold reduction in bacterial killing by moxifloxacin, and the phenomenon was dependent on intact mgrA. Taken together, these new data showed that phosphoregulation of MgrA at low pH reverses its repression of norB expression, conferring resistance to moxifloxacin.
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Inference of the transcriptional regulatory network in Staphylococcus aureus by integration of experimental and genomics-based evidence. J Bacteriol 2011; 193:3228-40. [PMID: 21531804 DOI: 10.1128/jb.00350-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Transcriptional regulatory networks are fine-tuned systems that help microorganisms respond to changes in the environment and cell physiological state. We applied the comparative genomics approach implemented in the RegPredict Web server combined with SEED subsystem analysis and available information on known regulatory interactions for regulatory network reconstruction for the human pathogen Staphylococcus aureus and six related species from the family Staphylococcaceae. The resulting reference set of 46 transcription factor regulons contains more than 1,900 binding sites and 2,800 target genes involved in the central metabolism of carbohydrates, amino acids, and fatty acids; respiration; the stress response; metal homeostasis; drug and metal resistance; and virulence. The inferred regulatory network in S. aureus includes ∼320 regulatory interactions between 46 transcription factors and ∼550 candidate target genes comprising 20% of its genome. We predicted ∼170 novel interactions and 24 novel regulons for the control of the central metabolic pathways in S. aureus. The reconstructed regulons are largely variable in the Staphylococcaceae: only 20% of S. aureus regulatory interactions are conserved across all studied genomes. We used a large-scale gene expression data set for S. aureus to assess relationships between the inferred regulons and gene expression patterns. The predicted reference set of regulons is captured within the Staphylococcus collection in the RegPrecise database (http://regprecise.lbl.gov).
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Control of thioredoxin reductase gene (trxB) transcription by SarA in Staphylococcus aureus. J Bacteriol 2010; 192:336-45. [PMID: 19854896 DOI: 10.1128/jb.01202-09] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thioredoxin reductase (encoded by trxB) protects Staphylococcus aureus against oxygen or disulfide stress and is indispensable for growth. Among the different sarA family mutants analyzed, transcription of trxB was markedly elevated in the sarA mutant under conditions of aerobic as well as microaerophilic growth, indicating that SarA acts as a negative regulator of trxB expression. Gel shift analysis showed that purified SarA protein binds directly to the trxB promoter region DNA in vitro. DNA binding of SarA was essential for repression of trxB transcription in vivo in S. aureus. Northern blot analysis and DNA binding studies of the purified wild-type SarA and the mutant SarAC9G with oxidizing agents indicated that oxidation of Cys-9 reduced the binding of SarA to the trxB promoter DNA. Oxidizing agents, in particular diamide, could further enhance transcription of the trxB gene in the sarA mutant, suggesting the presence of a SarA-independent mode of trxB induction. Analysis of two oxidative stress-responsive sarA regulatory target genes, trxB and sodM, with various mutant sarA constructs showed a differential ability of the SarA to regulate expression of the two above-mentioned genes in vivo. The overall data demonstrate the important role played by SarA in modulating expression of genes involved in oxidative stress resistance in S. aureus.
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McCallum N, Berger-Bächi B, Senn MM. Regulation of antibiotic resistance in Staphylococcus aureus. Int J Med Microbiol 2009; 300:118-29. [PMID: 19800843 DOI: 10.1016/j.ijmm.2009.08.015] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Staphylococcus aureus has a formidable ability to adapt to varying environmental conditions and an extraordinary capacity to rapidly become resistant to virtually all antibiotics. Resistance develops either through mutations and rearrangements within the staphylococcal genome, or by the acquisition of resistance determinants. Antibiotic resistances often impose a fitness burden on the host. Such biological costs can be reduced by tight regulation and antibiotic-inducible expression of resistance genes, or by compensatory mutations. Resistance induction by antibiotics can be mediated by dedicated, antibiotic-recognizing signal transducers or by mechanisms relieving translational attenuation. Antibiotic tolerance and the expression of resistance phenotypes can also be strongly influenced by the genetic backgrounds of strains and several other factors. Modification and indirect regulation of resistance levels can occur by mutations that alter gene expression or substrate specificity of genes contributing to resistance. Insertion elements can alter resistance profiles by turning relevant genes on or off. Environmental conditions and stress response mechanisms triggered by perturbation of the cell envelope, DNA damage, or faulty intermediary metabolism can also have an impact on resistance development and expression. Clinically relevant resistance is often built up through multiple steps, each of which contributes to an increase in resistance. The driving force behind resistance formation is antibiotic stress, and under clinical conditions selection for resistance is continuously competing with selection for bacterial fitness.
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Affiliation(s)
- Nadine McCallum
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 32, CH-8006 Zürich, Switzerland
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