1
|
Paquette AR, Payne SR, McKay GA, Brazeau-Henrie JT, Darnowski MG, Kammili A, Bernal F, Mah TF, Gruenheid S, Nguyen D, Boddy CN. RpoN-Based stapled peptides with improved DNA binding suppress Pseudomonas aeruginosa virulence. RSC Med Chem 2022; 13:445-455. [PMID: 35647551 PMCID: PMC9020619 DOI: 10.1039/d1md00371b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 02/02/2022] [Indexed: 11/21/2022] Open
Abstract
Stapled peptides have the ability to mimic α-helices involved in protein binding and have proved to be effective pharmacological agents for disrupting protein-protein interactions. DNA-binding proteins such as transcription factors bind their cognate DNA sequences via an α-helix interacting with the major groove of DNA. We previously developed a stapled peptide based on the bacterial alternative sigma factor RpoN capable of binding the RpoN DNA promoter sequence and inhibiting RpoN-mediated expression in Escherichia coli. We have elucidated a structure-activity relationship for DNA binding by this stapled peptide, improving DNA binding affinity constants in the high nM range. Lead peptides were shown to have low toxicity as determined by their low hemolytic activity at 100 μM and were shown to have anti-virulence activity in a Galleria mellonella model of Pseudomonas aeruginosa infection. These findings support further preclinical development of stapled peptides as antivirulence agents targeting P. aeruginosa.
Collapse
Affiliation(s)
- André R. Paquette
- Department of Chemistry and Biomolecular Sciences, University of OttawaOttawaONK1N 6N5 Canada
| | - Sterling R. Payne
- Laboratory of Protein Dynamics and Signaling, National Cancer Institute, National Institutes of HealthFrederickMD 21702USA
| | - Geoffrey A. McKay
- Meakins-Christie Laboratories, Research Institute of the McGill University Health CentreMontrealQuebec H4A 3J1Canada
| | | | - Micheal G. Darnowski
- Department of Chemistry and Biomolecular Sciences, University of OttawaOttawaONK1N 6N5 Canada
| | - Anitha Kammili
- Department of Chemistry and Biomolecular Sciences, University of Ottawa Ottawa ON K1N 6N5 Canada
| | - Federico Bernal
- Laboratory of Protein Dynamics and Signaling, National Cancer Institute, National Institutes of HealthFrederickMD 21702USA
| | - Thien-Fah Mah
- Department of Biochemistry, Microbiology, and Immunology, University of OttawaOttawaONK1H 8M5Canada
| | | | - Dao Nguyen
- Meakins-Christie Laboratories, Research Institute of the McGill University Health CentreMontrealQuebec H4A 3J1Canada,Department of Medicine, McGill UniversityMontrealQuebec H4A 3J1Canada
| | - Christopher N. Boddy
- Department of Chemistry and Biomolecular Sciences, University of OttawaOttawaONK1N 6N5 Canada
| |
Collapse
|
2
|
de Pina LC, da Silva FSH, Galvão TC, Pauer H, Ferreira RBR, Antunes LCM. The role of two-component regulatory systems in environmental sensing and virulence in Salmonella. Crit Rev Microbiol 2021; 47:397-434. [PMID: 33751923 DOI: 10.1080/1040841x.2021.1895067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Adaptation to environments with constant fluctuations imposes challenges that are only overcome with sophisticated strategies that allow bacteria to perceive environmental conditions and develop an appropriate response. The gastrointestinal environment is a complex ecosystem that is home to trillions of microorganisms. Termed microbiota, this microbial ensemble plays important roles in host health and provides colonization resistance against pathogens, although pathogens have evolved strategies to circumvent this barrier. Among the strategies used by bacteria to monitor their environment, one of the most important are the sensing and signalling machineries of two-component systems (TCSs), which play relevant roles in the behaviour of all bacteria. Salmonella enterica is no exception, and here we present our current understanding of how this important human pathogen uses TCSs as an integral part of its lifestyle. We describe important aspects of these systems, such as the stimuli and responses involved, the processes regulated, and their roles in virulence. We also dissect the genomic organization of histidine kinases and response regulators, as well as the input and output domains for each TCS. Lastly, we explore how these systems may be promising targets for the development of antivirulence therapeutics to combat antibiotic-resistant infections.
Collapse
Affiliation(s)
- Lucindo Cardoso de Pina
- Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.,Programa de Pós-Graduação em Biociências, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.,Programa de Pós-Graduação Ciência para o Desenvolvimento, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | | | - Teca Calcagno Galvão
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Heidi Pauer
- Centro de Desenvolvimento Tecnológico em Saúde, Fundação Oswaldo Cruz, Instituto Nacional de Ciência e Tecnologia de Inovação em Doenças de Populações Negligenciadas, Rio de Janeiro, Brazil
| | | | - L Caetano M Antunes
- Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.,Centro de Desenvolvimento Tecnológico em Saúde, Fundação Oswaldo Cruz, Instituto Nacional de Ciência e Tecnologia de Inovação em Doenças de Populações Negligenciadas, Rio de Janeiro, Brazil.,Laboratório de Pesquisa em Infecção Hospitalar, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| |
Collapse
|
3
|
Wang CH, Hsieh YH, Powers ZM, Kao CY. Defeating Antibiotic-Resistant Bacteria: Exploring Alternative Therapies for a Post-Antibiotic Era. Int J Mol Sci 2020; 21:E1061. [PMID: 32033477 PMCID: PMC7037027 DOI: 10.3390/ijms21031061] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/04/2020] [Accepted: 02/04/2020] [Indexed: 12/11/2022] Open
Abstract
Antibiotics are one of the greatest medical advances of the 20th century, however, they are quickly becoming useless due to antibiotic resistance that has been augmented by poor antibiotic stewardship and a void in novel antibiotic discovery. Few novel classes of antibiotics have been discovered since 1960, and the pipeline of antibiotics under development is limited. We therefore are heading for a post-antibiotic era in which common infections become untreatable and once again deadly. There is thus an emergent need for both novel classes of antibiotics and novel approaches to treatment, including the repurposing of existing drugs or preclinical compounds and expanded implementation of combination therapies. In this review, we highlight to utilize alternative drug targets/therapies such as combinational therapy, anti-regulator, anti-signal transduction, anti-virulence, anti-toxin, engineered bacteriophages, and microbiome, to defeat antibiotic-resistant bacteria.
Collapse
Affiliation(s)
- Chih-Hung Wang
- Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan;
| | - Yi-Hsien Hsieh
- Institute of Biochemistry, Microbiology and Immunology, Chung Shan Medical University, Taichung 40201, Taiwan;
| | - Zachary M. Powers
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706, USA;
| | - Cheng-Yen Kao
- Institute of Microbiology and Immunology, School of Life Science, National Yang-Ming University, Taipei 11221, Taiwan
| |
Collapse
|
4
|
Stress-induced adaptations in Salmonella: A ground for shaping its pathogenesis. Microbiol Res 2019; 229:126311. [DOI: 10.1016/j.micres.2019.126311] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 08/01/2019] [Accepted: 08/06/2019] [Indexed: 12/12/2022]
|
5
|
Bhagirath AY, Li Y, Patidar R, Yerex K, Ma X, Kumar A, Duan K. Two Component Regulatory Systems and Antibiotic Resistance in Gram-Negative Pathogens. Int J Mol Sci 2019; 20:E1781. [PMID: 30974906 PMCID: PMC6480566 DOI: 10.3390/ijms20071781] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 12/17/2022] Open
Abstract
Gram-negative pathogens such as Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa are the leading cause of nosocomial infections throughout the world. One commonality shared among these pathogens is their ubiquitous presence, robust host-colonization and most importantly, resistance to antibiotics. A significant number of two-component systems (TCSs) exist in these pathogens, which are involved in regulation of gene expression in response to environmental signals such as antibiotic exposure. While the development of antimicrobial resistance is a complex phenomenon, it has been shown that TCSs are involved in sensing antibiotics and regulating genes associated with antibiotic resistance. In this review, we aim to interpret current knowledge about the signaling mechanisms of TCSs in these three pathogenic bacteria. We further attempt to answer questions about the role of TCSs in antimicrobial resistance. We will also briefly discuss how specific two-component systems present in K. pneumoniae, A. baumannii, and P. aeruginosa may serve as potential therapeutic targets.
Collapse
Affiliation(s)
- Anjali Y Bhagirath
- Department of Oral Biology, Rady Faculty of Health Sciences, University of Manitoba, 780 Bannatyne Ave, Winnipeg, MB R3E 0J9, Canada.
| | - Yanqi Li
- Department of Oral Biology, Rady Faculty of Health Sciences, University of Manitoba, 780 Bannatyne Ave, Winnipeg, MB R3E 0J9, Canada.
| | - Rakesh Patidar
- Department of Microbiology, Faculty of Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada.
| | - Katherine Yerex
- Department of Oral Biology, Rady Faculty of Health Sciences, University of Manitoba, 780 Bannatyne Ave, Winnipeg, MB R3E 0J9, Canada.
| | - Xiaoxue Ma
- Department of Oral Biology, Rady Faculty of Health Sciences, University of Manitoba, 780 Bannatyne Ave, Winnipeg, MB R3E 0J9, Canada.
| | - Ayush Kumar
- Department of Microbiology, Faculty of Sciences, University of Manitoba, Winnipeg, MB R3E 0J9, Canada.
| | - Kangmin Duan
- Department of Oral Biology, Rady Faculty of Health Sciences, University of Manitoba, 780 Bannatyne Ave, Winnipeg, MB R3E 0J9, Canada.
- Department of Medical Microbiology & Infectious Diseases, Rady Faculty of Health Sciences, University of Manitoba, 780 Bannatyne Ave, Winnipeg, MB R3E 0J9, Canada.
| |
Collapse
|
6
|
Gart EV, Suchodolski JS, Welsh TH, Alaniz RC, Randel RD, Lawhon SD. Salmonella Typhimurium and Multidirectional Communication in the Gut. Front Microbiol 2016; 7:1827. [PMID: 27920756 PMCID: PMC5118420 DOI: 10.3389/fmicb.2016.01827] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 10/31/2016] [Indexed: 12/20/2022] Open
Abstract
The mammalian digestive tract is home to trillions of microbes, including bacteria, archaea, protozoa, fungi, and viruses. In monogastric mammals the stomach and small intestine harbor diverse bacterial populations but are typically less populated than the colon. The gut bacterial community (microbiota hereafter) varies widely among different host species and individuals within a species. It is influenced by season of the year, age of the host, stress and disease. Ideally, the host and microbiota benefit each other. The host provides nutrients to the microbiota and the microbiota assists the host with digestion and nutrient metabolism. The resident microbiota competes with pathogens for space and nutrients and, through this competition, protects the host in a phenomenon called colonization resistance. The microbiota participates in development of the host immune system, particularly regulation of autoimmunity and mucosal immune response. The microbiota also shapes gut–brain communication and host responses to stress; and, indeed, the microbiota is a newly recognized endocrine organ within mammalian hosts. Salmonella enterica serovar Typhimurium (S. Typhimurium hereafter) is a food-borne pathogen which adapts to and alters the gastrointestinal (GI) environment. In the GI tract, S. Typhimurium competes with the microbiota for nutrients and overcomes colonization resistance to establish infection. To do this, S. Typhimurium uses multiple defense mechanisms to resist environmental stressors, like the acidic pH of the stomach, and virulence mechanisms which allow it to invade the intestinal epithelium and disseminate throughout the host. To coordinate gene expression and disrupt signaling within the microbiota and between host and microbiota, S. Typhimurium employs its own chemical signaling and may regulate host hormone metabolism. This review will discuss the multidirectional interaction between S. Typhimurium, host and microbiota as well as mechanisms that allow S. Typhimurium to succeed in the gut.
Collapse
Affiliation(s)
- Elena V Gart
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station TX, USA
| | - Jan S Suchodolski
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Texas A&M University, College Station TX, USA
| | - Thomas H Welsh
- Department of Animal Science, College of Agriculture and Life Sciences, Texas A&M University, College Station TX, USA
| | - Robert C Alaniz
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Texas A&M University, College Station TX, USA
| | | | - Sara D Lawhon
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station TX, USA
| |
Collapse
|
7
|
Zhou T, Yin C, Zhang Y, Shi H, Wang J, Sun L, Shao X, Gao R, Wang W, Deng X. Lon Protease Is Involved in RhpRS-Mediated Regulation of Type III Secretion in Pseudomonas syringae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:807-814. [PMID: 27657922 DOI: 10.1094/mpmi-06-16-0114-r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Pseudomonas syringae depends on the type III secretion system (T3SS) to directly translocate effectors into host cells. Previously, we reported a nonpathogenic rhpS mutant, suggesting that the two-component transduction system rhpRS is an important regulator of T3SS in P. syringae. rhpRS regulates itself and a variety of downstream genes under an inverted repeat element promoter in a phosphorylation-dependent manner. Here, we identify lon as a suppressor of the rhpS mutant through transposon screening. A lon/rhpS double mutant restored the phenotypes of the rhpS mutant. The expression level of lon was higher in rhpS and other T3SS-deficient mutants than the wild-type strain, suggesting a negative feedback mechanism between lon and T3SS genes. lon was also induced by a novel T3SS inhibitor, acetate, which substantially compromises the activation of T3SS genes in minimal medium and bacterial growth in host plants.
Collapse
Affiliation(s)
- Tianhong Zhou
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Chunyan Yin
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Yingchao Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Heng Shi
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Jingru Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Linbo Sun
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Xiaolong Shao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Ruxia Gao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Wei Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| | - Xin Deng
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, Tianjin 300457, China
| |
Collapse
|
8
|
Moreira CG, Sperandio V. The Epinephrine/Norepinephrine/Autoinducer-3 Interkingdom Signaling System in Escherichia coli O157:H7. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 874:247-61. [PMID: 26589223 DOI: 10.1007/978-3-319-20215-0_12] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Epinephrine/norepinephrine/AI-3 signaling is used as an interkingdom chemical signaling system between microbes and their hosts. This system is also exploited by pathogens to regulate virulence traits. In enterohemorrhagic E. coli (EHEC) O157:H7, it is essential for pathogenesis and flagella motility. These three signals activate expression of a pathogenicity island named locus of enterocyte effacement (LEE), Shiga toxin, and the flagella regulon. These signals are sensed by the two-component system QseBC, whereas the bacterial membrane receptor QseC autophosphorylates and phosphorylates the QseB response regulator initiating a complex phosphorelay signaling cascade that activates the expression of a second two-component system, QseEF. The QseEF two-component system is also involved in the expression of the virulence genes, and it senses epinephrine, phosphate, and sulfate. This complex signaling cascade still needs to be completely elucidated.
Collapse
Affiliation(s)
- Cristiano G Moreira
- Molecular Microbiology Department, University of Texas Southwestern Medical Center, 6000 Harry Hines Bvld, Dallas, 75390, TX, USA.
| | - Vanessa Sperandio
- Molecular Microbiology Department, University of Texas Southwestern Medical Center, 6000 Harry Hines Bvld, Dallas, 75390, TX, USA
| |
Collapse
|
9
|
Modulation of the Interaction of Enteric Bacteria with Intestinal Mucosa by Stress-Related Catecholamines. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 874:143-66. [PMID: 26589217 DOI: 10.1007/978-3-319-20215-0_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Stress associated with parturition, transport or mixing has long been correlated with enhanced faecal excretion of diarrhoeal zoonotic pathogens in animals such as Salmonella enterica and Escherichia coli. It may also predispose humans to infection and/or be associated with more severe outcomes. One possible explanation for this phenomenon is the ability of enteric bacterial pathogens to sense and respond to host stress-related catecholamines. This article reviews evidence of the ability of catecholamine hormones to modulate interactions between Gram-negative diarrhoeal pathogens and intestinal mucosa, as well as the molecular mechanisms that may be at work.
Collapse
|
10
|
Telke AA, Rolain JM. Functional genomics to discover antibiotic resistance genes: The paradigm of resistance to colistin mediated by ethanolamine phosphotransferase in Shewanella algae MARS 14. Int J Antimicrob Agents 2015; 46:648-52. [PMID: 26498987 DOI: 10.1016/j.ijantimicag.2015.09.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 09/01/2015] [Accepted: 09/03/2015] [Indexed: 02/06/2023]
Abstract
Shewanella algae MARS 14 is a colistin-resistant clinical isolate retrieved from bronchoalveolar lavage of a hospitalised patient. A functional genomics strategy was employed to discover the molecular support for colistin resistance in S. algae MARS 14. A pZE21 MCS-1 plasmid-based genomic expression library was constructed in Escherichia coli TOP10. The estimated library size was 1.30×10(8) bp. Functional screening of colistin-resistant clones was carried out on Luria-Bertani agar containing 8 mg/L colistin. Five colistin-resistant clones were obtained after complete screening of the genomic expression library. Analysis of DNA sequencing results found a unique gene in all selected clones. Amino acid sequence analysis of this unique gene using the Integrated Microbial Genomes (IMG) and KEGG databases revealed that this gene encodes ethanolamine phosphotransferase (EptA, or so-called PmrC). Reverse transcription PCR analysis indicated that resistance to colistin in S. algae MARS 14 was associated with overexpression of EptA (27-fold increase), which plays a crucial role in the arrangement of outer membrane lipopolysaccharide.
Collapse
Affiliation(s)
- Amar A Telke
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France
| | - Jean-Marc Rolain
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France.
| |
Collapse
|
11
|
Nuri R, Shprung T, Shai Y. Defensive remodeling: How bacterial surface properties and biofilm formation promote resistance to antimicrobial peptides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:3089-100. [PMID: 26051126 DOI: 10.1016/j.bbamem.2015.05.022] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 05/25/2015] [Accepted: 05/26/2015] [Indexed: 11/15/2022]
Abstract
Multidrug resistance bacteria are a major concern worldwide. These pathogens cannot be treated with conventional antibiotics and thus alternative therapeutic agents are needed. Antimicrobial peptides (AMPs) are considered to be good candidates for this purpose. Most AMPs are short and positively charged amphipathic peptides, which are found in all known forms of life. AMPs are known to kill bacteria by binding to the negatively charged bacterial surface, and in most cases cause membrane disruption. Resistance toward AMPs can be developed, by modification of bacterial surface molecules, secretion of protective material and up-regulation or elimination of specific proteins. Because of the general mechanisms of attachment and action of AMPs, bacterial resistance to AMPs often involves biophysical and biochemical changes such as surface rigidity, cell wall thickness, surface charge, as well as membrane and cell wall modification. Here we focus on the biophysical, surface and surrounding changes that bacteria undergo in acquiring resistance to AMPs. In addition we discuss the question of whether bacterial resistance to administered AMPs might compromise our innate immunity to endogenous AMPs. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.
Collapse
Affiliation(s)
- Reut Nuri
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tal Shprung
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yechiel Shai
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
| |
Collapse
|
12
|
Kendall MM, Sperandio V. Cell-to-Cell Signaling in Escherichia coli and Salmonella. EcoSal Plus 2014; 6:10.1128/ecosalplus.ESP-0002-2013. [PMID: 26442936 PMCID: PMC4229655 DOI: 10.1128/ecosalplus.esp-0002-2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Indexed: 01/21/2023]
Abstract
Bacteria must be able to respond rapidly to changes in the environment to survive. One means of coordinating gene expression relies on tightly regulated and complex signaling systems. One of the first signaling systems that was described in detail is quorum sensing (QS). During QS, a bacterial cell produces and secretes a signaling molecule called an autoinducer (AI). As the density of the bacterial population increases, so does the concentration of secreted AI molecules, thereby allowing a bacterial species to coordinate gene expression based on population density. Subsequent studies have demonstrated that bacteria are also able to detect signal molecules produced by other species of bacteria as well as hormones produced by their mammalian hosts. This type of signaling interaction has been termed cell-to-cell signaling because it does not rely on a threshold concentration of bacterial cells. This review discusses the three main types of cell-to-cell signaling mechanisms used by Escherichia coli and Salmonella: the LuxR process, in which E. coli and Salmonella detect signals produced by other species of bacteria; the LuxS/AI-2 system, in which E. coli and Salmonella participate in intra- and interspecies signaling; and the AI-3/epinephrine/norepinephrine system, in which E. coli and Salmonella recognize self-produced AI, signal produced by other microbes, and/or the human stress hormones epinephrine and/or norepinephrine.
Collapse
Affiliation(s)
- Melissa M. Kendall
- Department of Microbiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
| | - Vanessa Sperandio
- Department of Microbiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390, USA
| |
Collapse
|
13
|
Chen HD, Groisman EA. The biology of the PmrA/PmrB two-component system: the major regulator of lipopolysaccharide modifications. Annu Rev Microbiol 2013; 67:83-112. [PMID: 23799815 DOI: 10.1146/annurev-micro-092412-155751] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The ability of gram-negative bacteria to resist killing by antimicrobial agents and to avoid detection by host immune systems often entails modification to the lipopolysaccharide (LPS) in their outer membrane. In this review, we examine the biology of the PmrA/PmrB two-component system, the major regulator of LPS modifications in the enteric pathogen Salmonella enterica. We examine the signals that activate the sensor PmrB and the targets controlled by the transcriptional regulator PmrA. We discuss the PmrA/PmrB-dependent chemical decorations of the LPS and their role in resistance to antibacterial agents. We analyze the feedback mechanisms that modulate the activity and thus output of the PmrA/PmrB system, dictating when, where, and to what extent bacteria modify their LPS. Finally, we explore the qualitative and quantitative differences in gene expression outputs resulting from the distinct PmrA/PmrB circuit architectures in closely related bacteria, which may account for their differential survival in various ecological niches.
Collapse
|
14
|
Characterization of a ferrous iron-responsive two-component system in nontypeable Haemophilus influenzae. J Bacteriol 2012; 194:6162-73. [PMID: 22961857 DOI: 10.1128/jb.01465-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Nontypeable Haemophilus influenzae (NTHI), an opportunistic pathogen that is commonly found in the human upper respiratory tract, has only four identified two-component signal transduction systems. One of these, an ortholog to the QseBC (quorum-sensing Escherichia coli) system, was characterized. This system, designated firRS, was found to be transcribed in an operon with a gene encoding a small, predicted periplasmic protein with an unknown function, ygiW. The ygiW-firRS operon exhibited a unique feature with an attenuator present between ygiW and firR that caused the ygiW transcript level to be 6-fold higher than the ygiW-firRS transcript level. FirRS induced expression of ygiW and firR, demonstrating that FirR is an autoactivator. Unlike the QseBC system of E. coli, FirRS does not respond to epinephrine or norepinephrine. FirRS signal transduction was stimulated when NTHI cultures were exposed to ferrous iron or zinc but was unresponsive to ferric iron. Notably, the ferrous iron-responsive activation only occurred when a putative iron-binding site in FirS and the key phosphorylation aspartate in FirR were intact. FirRS was also activated when cultures were exposed to cold shock. Mutants in ygiW, firR, and firS were attenuated during pulmonary infection, but not otitis media. These data demonstrate that the H. influenzae strain 2019 FirRS is a two-component regulatory system that senses ferrous iron and autoregulates its own operon.
Collapse
|
15
|
Garai P, Gnanadhas DP, Chakravortty D. Salmonella enterica serovars Typhimurium and Typhi as model organisms: revealing paradigm of host-pathogen interactions. Virulence 2012; 3:377-88. [PMID: 22722237 PMCID: PMC3478240 DOI: 10.4161/viru.21087] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The lifestyle of intracellular pathogens has always questioned the skill of a microbiologist in the context of finding the permanent cure to the diseases caused by them. The best tool utilized by these pathogens is their ability to reside inside the host cell, which enables them to easily bypass the humoral immunity of the host, such as the complement system. They further escape from the intracellular immunity, such as lysosome and inflammasome, mostly by forming a protective vacuole-bound niche derived from the host itself. Some of the most dreadful diseases are caused by these vacuolar pathogens, for example, tuberculosis by Mycobacterium or typhoid fever by Salmonella. To deal with such successful pathogens therapeutically, the knowledge of a host-pathogen interaction system becomes primarily essential, which further depends on the use of a model system. A well characterized pathogen, namely Salmonella, suits the role of a model for this purpose, which can infect a wide array of hosts causing a variety of diseases. This review focuses on various such aspects of research on Salmonella which are useful for studying the pathogenesis of other intracellular pathogens.
Collapse
Affiliation(s)
- Preeti Garai
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research and Biosafety Laboratories, Indian Institute of Science, Bangalore, India
| | | | | |
Collapse
|
16
|
Selection of Salmonella enterica serovar Typhi genes involved during interaction with human macrophages by screening of a transposon mutant library. PLoS One 2012; 7:e36643. [PMID: 22574205 PMCID: PMC3344905 DOI: 10.1371/journal.pone.0036643] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 04/04/2012] [Indexed: 12/21/2022] Open
Abstract
The human-adapted Salmonella enterica serovar Typhi (S. Typhi) causes a systemic infection known as typhoid fever. This disease relies on the ability of the bacterium to survive within macrophages. In order to identify genes involved during interaction with macrophages, a pool of approximately 105 transposon mutants of S. Typhi was subjected to three serial passages of 24 hours through human macrophages. Mutants recovered from infected macrophages (output) were compared to the initial pool (input) and those significantly underrepresented resulted in the identification of 130 genes encoding for cell membrane components, fimbriae, flagella, regulatory processes, pathogenesis, and many genes of unknown function. Defined deletions in 28 genes or gene clusters were created and mutants were evaluated in competitive and individual infection assays for uptake and intracellular survival during interaction with human macrophages. Overall, 26 mutants had defects in the competitive assay and 14 mutants had defects in the individual assay. Twelve mutants had defects in both assays, including acrA, exbDB, flhCD, fliC, gppA, mlc, pgtE, typA, waaQGP, SPI-4, STY1867-68, and STY2346. The complementation of several mutants by expression of plasmid-borne wild-type genes or gene clusters reversed defects, confirming that the phenotypic impairments within macrophages were gene-specific. In this study, 35 novel phenotypes of either uptake or intracellular survival in macrophages were associated with Salmonella genes. Moreover, these results reveal several genes encoding molecular mechanisms not previously known to be involved in systemic infection by human-adapted typhoidal Salmonella that will need to be elucidated.
Collapse
|
17
|
Steenackers H, Hermans K, Vanderleyden J, De Keersmaecker SC. Salmonella biofilms: An overview on occurrence, structure, regulation and eradication. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.01.038] [Citation(s) in RCA: 314] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
18
|
Bearson BL, Bearson SM. Host specific differences alter the requirement for certain Salmonella genes during swine colonization. Vet Microbiol 2011; 150:215-9. [DOI: 10.1016/j.vetmic.2010.12.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/10/2010] [Accepted: 12/21/2010] [Indexed: 12/20/2022]
|
19
|
Silent mischief: bacteriophage Mu insertions contaminate products of Escherichia coli random mutagenesis performed using suicidal transposon delivery plasmids mobilized by broad-host-range RP4 conjugative machinery. J Bacteriol 2010; 192:6418-27. [PMID: 20935093 DOI: 10.1128/jb.00621-10] [Citation(s) in RCA: 198] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Random transposon mutagenesis is the strategy of choice for associating a phenotype with its unknown genetic determinants. It is generally performed by mobilization of a conditionally replicating vector delivering transposons to recipient cells using broad-host-range RP4 conjugative machinery carried by the donor strain. In the present study, we demonstrate that bacteriophage Mu, which was deliberately introduced during the original construction of the widely used donor strains SM10 λpir and S17-1 λpir, is silently transferred to Escherichia coli recipient cells at high frequency, both by hfr and by release of Mu particles by the donor strain. Our findings suggest that bacteriophage Mu could have contaminated many random-mutagenesis experiments performed on Mu-sensitive species with these popular donor strains, leading to potential misinterpretation of the transposon mutant phenotype and therefore perturbing analysis of mutant screens. To circumvent this problem, we precisely mapped Mu insertions in SM10 λpir and S17-1 λpir and constructed a new Mu-free donor strain, MFDpir, harboring stable hfr-deficient RP4 conjugative functions and sustaining replication of Π-dependent suicide vectors. This strain can therefore be used with most of the available transposon-delivering plasmids and should enable more efficient and easy-to-analyze mutant hunts in E. coli and other Mu-sensitive RP4 host bacteria.
Collapse
|
20
|
Abstract
Salmonella enterica are Gram-negative enteric pathogens that cause typhoid fever and gastroenteritis in humans. Many bacteria, including Salmonella, use signal transduction cascades such as two-component regulatory systems to detect and respond to stimuli in the local microenvironment. During infection, environmental sensing allows bacteria to regulate gene expression to evade host immune defenses and thrive in vivo. Activation of the Salmonella two-component regulatory systems PhoP-PhoQ and PmrA-PmrB and the RcsC-RcsD-RcsB phosphorylay by specific environmental signals in the intestine and within host cells leads to several lipopolysaccharide modifications that promote bacterial survival, cationic antimicrobial peptide resistance and virulence. Many pathogens encode orthologs to Salmonella two-component regulatory systems and also modify the lipopolysaccharide to escape killing by the host immune response. However, these organisms often regulate their virulence genes, including those responsible for lipopolysaccharide modification, in ways that differ from Salmonella. Further examination of bacterial virulence gene regulation and lipopolysaccharide modifications may lead to improved antimicrobial therapies and vaccines.
Collapse
|
21
|
Bearson BL, Bearson SM, Lee IS, Brunelle BW. The Salmonella enterica serovar Typhimurium QseB response regulator negatively regulates bacterial motility and swine colonization in the absence of the QseC sensor kinase. Microb Pathog 2010; 48:214-9. [DOI: 10.1016/j.micpath.2010.03.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Revised: 03/02/2010] [Accepted: 03/04/2010] [Indexed: 10/19/2022]
|
22
|
QseC mediates Salmonella enterica serovar typhimurium virulence in vitro and in vivo. Infect Immun 2009; 78:914-26. [PMID: 20028809 DOI: 10.1128/iai.01038-09] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The autoinducer-3 (AI-3)/epinephrine (Epi)/norepinephrine (NE) interkingdom signaling system mediates chemical communication between bacteria and their mammalian hosts. The three signals are sensed by the QseC histidine kinase (HK) sensor. Salmonella enterica serovar Typhimurium is a pathogen that uses HKs to sense its environment and regulate virulence. Salmonella serovar Typhimurium invades epithelial cells and survives within macrophages. Invasion of epithelial cells is mediated by the type III secretion system (T3SS) encoded in Salmonella pathogenicity island 1 (SPI-1), while macrophage survival and systemic disease are mediated by the T3SS encoded in SPI-2. Here we show that QseC plays an important role in Salmonella serovar Typhimurium pathogenicity. A qseC mutant was impaired in flagellar motility, in invasion of epithelial cells, and in survival within macrophages and was attenuated for systemic infection in 129x1/SvJ mice. QseC acts globally, regulating expression of genes within SPI-1 and SPI-2 in vitro and in vivo (during infection of mice). Additionally, dopamine beta-hydroxylase knockout (Dbh(-)(/)(-)) mice that do not produce Epi or NE showed different susceptibility to Salmonella serovar Typhimurium infection than wild-type mice. These data suggest that the AI-3/Epi/NE signaling system is a key factor during Salmonella serovar Typhimurium pathogenesis in vitro and in vivo. Elucidation of the role of this interkingdom signaling system in Salmonella serovar Typhimurium should contribute to a better understanding of the complex interplay between the pathogen and the host during infection.
Collapse
|
23
|
Meibom KL, Barel M, Charbit A. Loops and networks in control of Francisella tularensis virulence. Future Microbiol 2009; 4:713-29. [PMID: 19659427 DOI: 10.2217/fmb.09.37] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Francisella tularensis is a highly infectious, Gram-negative bacterium responsible for the disease tularemia in a broad variety of animals, including humans. F. tularensis intracellular multiplication occurs mainly in macrophages. However, F. tularensis is able to infect many other cell types, including other phagocytic (dendritic cells, polymorphonuclear leukocytes) and nonphagocytic (alveolar epithelial cells, hepatocytes, endothelial cells and fibroblasts) cells. The ability of professional phagocytic cells to engulf and kill microbes is an essential component of innate defense. The ability of F. tularensis to impair phagocyte function and survive in the cytosol of infected cells thus constitutes a central aspect of its virulence. The F. tularensis intracellular lifecycle relies on the tightly regulated expression of a series of genes. The unraveling secrets of the regulatory cascades governing the regulation of virulence of F. tularensis will be discussed along with future challenges yet to be solved.
Collapse
Affiliation(s)
- Karin L Meibom
- INSERM U570, Université Paris Descartes, Faculté de Médecine Necker Enfants-Malades, 75730, Paris Cedex 15, France.
| | | | | |
Collapse
|
24
|
Cell-to-Cell Signaling in Escherichia coli and Salmonella. EcoSal Plus 2009; 3. [PMID: 26443762 DOI: 10.1128/ecosalplus.5.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bacteria must be able to respond rapidly to changes in the environment in order to survive. One means of coordinating gene expression relies on tightly regulated and complex signaling systems. One of the first signaling systems that was described in detail is quorum sensing (QS). During QS, a bacterial cell produces and secretes a signaling molecule called an autoinducer (AI). As the density of the bacterial population increases, so does the concentration of secreted AI molecules, thereby allowing a bacterial species to coordinate gene expression based on population density. Subsequent studies have demonstrated that bacteria are also able to detect signal molecules produced by other species of bacteria as well as hormones produced by their mammalian hosts. These types of signaling interactions have been termed cell-to-cell signaling because the interaction does not rely on a threshold concentration of bacterial cells. This review discusses the three main types of cell-to-cell signaling mechanisms used by E. coli and Salmonella, including the LuxR process, in which E. coli and Salmonella detect signals produced by other species of bacteria; the LuxS/AI-2 system, in which E. coli and Salmonella participate in intra- and interspecies signaling; and the AI-3/ epinephrine/norepinephrine system, in which E. coli and Salmonella recognize self-produced AI, signal produced by other microbes, and/or the human stress hormones epinephrine or norepinephrine.
Collapse
|
25
|
Lebeis SL, Kalman D. Aligning antimicrobial drug discovery with complex and redundant host-pathogen interactions. Cell Host Microbe 2009; 5:114-22. [PMID: 19218083 DOI: 10.1016/j.chom.2009.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Drug-resistant microorganisms pose an enormous threat to public health. Here we provide examples of experimental approaches that offer novel ways to think about drug development considering the complexity inherent to host-pathogen interactions. Emergent themes include (1) targeting pathogenicity rather than microbial growth, (2) targeting the host or host-pathogen interface rather than the pathogen, (3) facilitating pathogen-specific immune responses, and (4) utilizing systems-based approaches to identify new drug targets and validate drug efficacy. We posit that together these approaches may allow identification of drugs that disrupt pathogenesis and allow the immune system time to protect, but do not easily engender resistance.
Collapse
Affiliation(s)
- Sarah L Lebeis
- Microbiology and Molecular Genetics Graduate Program, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | | |
Collapse
|
26
|
The roles of two-component systems in virulence of pathogenic Escherichia coli and Shigella spp. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 631:189-99. [PMID: 18792690 DOI: 10.1007/978-0-387-78885-2_13] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Two-component systems (TCSs) are well conserved among E. coli strains, including pathogenic E. coli and also closely related Shigella spp. Although 25% of the genome of pathogenic E. coli is strain-specific, only small number of strain-specific TCSs is found. Regulation of virulence genes in response to environmental stimuli is partly dependent on TCSs commonly present in nonpathogenic E. coli strains. Some virulence genes are directly regulated by response regulator ofTCS but some are affected at posttranscriptional steps of production or assembly ofmacromolecule by TCS-induced products. In the process ofacquiringvirulence traits, regulatory systems for virulence genes expression seem to be built by integrating E. coli backbone TCSs with the virulence regulatory network via transcription regulatory gene.
Collapse
|
27
|
Rasko DA, Moreira CG, Li DR, Reading NC, Ritchie JM, Waldor MK, Williams N, Taussig R, Wei S, Roth M, Hughes DT, Huntley JF, Fina MW, Falck JR, Sperandio V. Targeting QseC signaling and virulence for antibiotic development. Science 2008; 321:1078-80. [PMID: 18719281 PMCID: PMC2605406 DOI: 10.1126/science.1160354] [Citation(s) in RCA: 383] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Many bacterial pathogens rely on a conserved membrane histidine sensor kinase, QseC, to respond to host adrenergic signaling molecules and bacterial signals in order to promote the expression of virulence factors. Using a high-throughput screen, we identified a small molecule, LED209, that inhibits the binding of signals to QseC, preventing its autophosphorylation and consequently inhibiting QseC-mediated activation of virulence gene expression. LED209 is not toxic and does not inhibit pathogen growth; however, this compound markedly inhibits the virulence of several pathogens in vitro and in vivo in animals. Inhibition of signaling offers a strategy for the development of broad-spectrum antimicrobial drugs.
Collapse
Affiliation(s)
- David A. Rasko
- Department of Microbiology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Cristiano G. Moreira
- Department of Microbiology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - De Run Li
- Department of Biochemistry, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Nicola C. Reading
- Department of Microbiology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jennifer M. Ritchie
- Channing Laboratory, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Matthew K. Waldor
- Channing Laboratory, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Noelle Williams
- Department of Biochemistry, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ron Taussig
- Department of Pharmacology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shuguang Wei
- Department of Biochemistry, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Michael Roth
- Department of Biochemistry, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - David T. Hughes
- Department of Microbiology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jason F. Huntley
- Department of Microbiology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Maggy W. Fina
- Department of Pharmacology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - John R. Falck
- Department of Biochemistry, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Pharmacology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vanessa Sperandio
- Department of Microbiology, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Biochemistry, University of Texas (UT) Southwestern Medical Center, Dallas, TX 75390, USA
| |
Collapse
|
28
|
The two-component system PhoPR of Clostridium acetobutylicum is involved in phosphate-dependent gene regulation. J Bacteriol 2008; 190:6559-67. [PMID: 18689481 DOI: 10.1128/jb.00574-08] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The phoPR gene locus of Clostridium acetobutylicum ATCC 824 comprises two genes, phoP and phoR. Deduced proteins are predicted to represent a response regulator and sensor kinase of a phosphate-dependent two-component regulatory system. We analyzed the expression patterns of phoPR in P(i)-limited chemostat cultures and in response to P(i) pulses. A basic transcription level under high-phosphate conditions was shown, and a significant increase in mRNA transcript levels was found when external P(i) concentrations dropped below 0.3 mM. In two-dimensional gel electrophoresis experiments, a 2.5-fold increase in PhoP was observed under P(i)-limiting growth conditions compared to growth with an excess of P(i). At least three different transcription start points for phoP were determined by primer extension analyses. Proteins PhoP and an N-terminally truncated *PhoR were individually expressed heterologously in Escherichia coli and purified. Autophosphorylation of *PhoR and phosphorylation of PhoP were shown in vitro. Electromobility shift assays proved that there was a specific binding of PhoP to the promoter region of the phosphate-regulated pst operon of C. acetobutylicum.
Collapse
|
29
|
Gunn JS. The Salmonella PmrAB regulon: lipopolysaccharide modifications, antimicrobial peptide resistance and more. Trends Microbiol 2008; 16:284-90. [PMID: 18467098 DOI: 10.1016/j.tim.2008.03.007] [Citation(s) in RCA: 243] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2007] [Revised: 03/19/2008] [Accepted: 03/28/2008] [Indexed: 11/30/2022]
Abstract
Microbes are able to sense and respond to their environment primarily through the use of two-component regulatory systems. Many of these systems activate virulence-factor expression and are regulated by host-derived signals, having evolved to control gene expression at the key time and place for optimal establishment and maintenance of infection. Salmonella spp. are enteric pathogens that are able to survive both within host macrophages during systemic spread and killing by innate immune factors at intestinal mucosal surfaces. This review focuses on a key mechanism of pathogenesis that involves the PmrA-PmrB two-component system, which is activated in vivo by direct or indirect means and regulates genes that modify lipopolysaccharide, aiding survival in host (and non-host) environments.
Collapse
Affiliation(s)
- John S Gunn
- Center for Microbial Interface Biology, Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, 460 W. 12th Avenue, Columbus, OH 43210-1214, USA.
| |
Collapse
|
30
|
Hughes DT, Sperandio V. Inter-kingdom signalling: communication between bacteria and their hosts. Nat Rev Microbiol 2008; 6:111-20. [PMID: 18197168 PMCID: PMC2667375 DOI: 10.1038/nrmicro1836] [Citation(s) in RCA: 472] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Microorganisms and their hosts communicate with each other through an array of hormonal signals. This cross-kingdom cell-to-cell signalling involves small molecules, such as hormones that are produced by eukaryotes and hormone-like chemicals that are produced by bacteria. Cell-to-cell signalling between bacteria, usually referred to as quorum sensing, was initially described as a means by which bacteria achieve signalling in microbial communities to coordinate gene expression within a population. Recent evidence shows, however, that quorum-sensing signalling is not restricted to bacterial cell-to-cell communication, but also allows communication between microorganisms and their hosts.
Collapse
Affiliation(s)
- David T Hughes
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA
| | | |
Collapse
|
31
|
Yang S, Peng Q, Zhang Q, Yi X, Choi CJ, Reedy RM, Charkowski AO, Yang CH. Dynamic regulation of GacA in type III secretion, pectinase gene expression, pellicle formation, and pathogenicity of Dickeya dadantii (Erwinia chrysanthemi 3937). MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:133-142. [PMID: 18052890 DOI: 10.1094/mpmi-21-1-0133] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Dickeya dadantii (Erwinia chrysanthemi 3937) secretes exoenzymes, including pectin-degrading enzymes, leading to the loss of structural integrity of plant cell walls. A type III secretion system (T3SS) is essential for full virulence of this bacterium within plant hosts. The GacS/GacA two-component signal transduction system participates in important biological roles in several gram-negative bacteria. In this study, a gacA deletion mutant (Ech137) of D. dadantii was constructed to investigate the effect of this mutation on pathogenesis and other phenotypes. Compared with wild-type D. dadantii, Ech137 had a delayed biofilm-pellicle formation. The production of pectate lyase (Pel), protease, and cellulase was diminished in Ech137 compared with the wild-type cells. Reduced transcription of two endo-Pel genes, pelD and pelL, was found in Ech137 using a green fluorescence protein-based fluorescence-activated cell sorter promoter activity assay. In addition, the transcription of T3SS genes dspE (an effector), hrpA (a structural protein of the T3SS pilus), and hrpN (a T3SS harpin) was reduced in Ech137. A lower amount of rsmB regulatory RNA was found in gacA mutant Ech137 compared with the wild-type bacterium by quantitative reverse-transcription polymerase chain reaction. Compared with wild-type D. dadantii, a lower amount of hrpL mRNA was observed in Ech137 at 12 h grown in medium. Although the role of RsmA, rsmB, and RsmC in D. dadantii is not clear, from the regulatory pathway revealed in E. carotovora, the lower expression of dspE, hrpA, and hrpN in Ech137 may be due to a post-transcriptional regulation of hrpL through the Gac-Rsm regulatory pathway. Consequently, the reduced exoenzyme production and Pel gene expression in the mutant may be sue partially to the regulatory role of rsmB-RsmA on exoenzyme expression. Similar to in vitro results, a lower expression of T3SS and pectinase genes of Ech137 also was observed in bacterial cells inoculated into Saintpaulia ionantha leaves, perhaps accounting for the observed reduction in local maceration. Interestingly, compared with the wild-type D. dadantii, although a lower concentration of Ech137 was observed at day 3 and 4 postinoculation, there is no significant difference in bacterial concentration between the wild-type bacterium and Ech137 in the early stage of infection. Finally, the nearly abolished systemic invasion ability of Ech137 suggests that GacA of D. dadantii is essential for the pathogenicity and systemic movement of the bacterium in S. ionantha.
Collapse
Affiliation(s)
- Shihui Yang
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI 53211, USA
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Zusman T, Aloni G, Halperin E, Kotzer H, Degtyar E, Feldman M, Segal G. The response regulator PmrA is a major regulator of the icm/dot type IV secretion system in Legionella pneumophila and Coxiella burnetii. Mol Microbiol 2007; 63:1508-23. [PMID: 17302824 DOI: 10.1111/j.1365-2958.2007.05604.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Legionella pneumophila and Coxiella burnetii have been shown to utilize the icm/dot type IV secretion system for pathogenesis and recently a large number of icm/dot-translocated substrates were identified in L. pneumophila. Bioinformatic analysis has revealed that 13 of the genes encoding for L. pneumophila-translocated substrates and five of the C. burnetii icm/dot genes, contain a conserved regulatory element that resembles the target sequence of the PmrA response regulator. Experimental analysis which included the construction of a L. pneumophila pmrA deletion mutant, intracellular growth analysis, comparison of gene expression between L. pneumophila wild type and the pmrA mutant, construction of mutations in the PmrA conserved regulatory element, controlled expression studies as well as mobility shift assays, demonstrated the direct relation between the PmrA regulator and the expression of L. pneumophila icm/dot-translocated substrates and several C. burnetii icm/dot genes. Furthermore, genomic analysis identified 35 L. pneumophila and 68 C. burnetii unique genes that contain the PmrA regulatory element and few of these genes from L. pneumophila were found to be new icm/dot-translocated substrates. Our results establish the PmrA regulator as a fundamental regulator of the icm/dot type IV secretion system in these two bacteria.
Collapse
Affiliation(s)
- Tal Zusman
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel
| | | | | | | | | | | | | |
Collapse
|