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Winther AR, Salehian Z, Bøe CA, Nesdal M, Håvarstein LS, Kjos M, Straume D. Decreased susceptibility to viscosin in Streptococcus pneumoniae. Microbiol Spectr 2024; 12:e0062424. [PMID: 38958463 PMCID: PMC11302323 DOI: 10.1128/spectrum.00624-24] [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: 03/08/2024] [Accepted: 05/30/2024] [Indexed: 07/04/2024] Open
Abstract
Growing numbers of infections caused by antibiotic-resistant Streptococcus pneumoniae strains are a major concern for healthcare systems that will require new antibiotics for treatment as well as preventative measures that reduce the number of infections. Lipopeptides are antimicrobial molecules, of which some are used as antibiotics, including the last resort antibiotics daptomycin and polymyxins. Here we have studied the antimicrobial effect of the cyclic lipopeptide viscosin on S. pneumoniae growth and morphology. Most lipopeptides function as surfactants that create pores in membrane layers, which is regarded as their main antimicrobial activity. We show that viscosin can inhibit growth of S. pneumoniae without disintegration of the cytoplasmic membrane. Instead, the cells developed abnormal shapes and misplaced new division sites. The cell wall of these bacteria appeared less dense in electron microscopy images, suggesting that viscosin interfered with normal cell wall synthesis. Corroborating this observation, a luciferase reporter assay was used to show that the two-component systems LiaFSR and CiaRH, which are known to be activated upon cell wall stress, were strongly induced by viscosin. Furthermore, a mutant displaying 1.8-fold decreased susceptibility to viscosin was generated by sequential exposure to increasing concentrations of the lipopeptide. The mutant suffered from significant fitness loss and had mutations in genes involved in fatty acid synthesis, teichoic acid synthesis, and cell wall synthesis as well as transcription and translation. How these mutations might be linked to decreased viscosin susceptibility is discussed.IMPORTANCEStreptococcus pneumoniae is a leading cause of bacterial pneumonia, sepsis, and meningitis in children, and the incidence of infections caused by antibiotic-resistant strains is increasing. Development of new antibiotics is therefore necessary to treat these types of infections in the future. Here, we have studied the activity of the antimicrobial lipopeptide viscosin on S. pneumoniae and show that in addition to having the typical membrane destabilizing activity of lipopeptides, viscosin inhibits pneumococcal growth by obstructing normal cell wall synthesis. This suggests a more specific mode of action than just the surfactant activity. Furthermore, we show that S. pneumoniae does not easily acquire resistance to viscosin, which makes it a promising molecule to explore further, for example, by synthesizing less toxic derivates that can be tested for therapeutic potential.
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Affiliation(s)
- Anja Ruud Winther
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Zhian Salehian
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | | | - Malene Nesdal
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Leiv Sigve Håvarstein
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Daniel Straume
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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2
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Pettersen JS, Nielsen FD, Andreassen PR, Møller-Jensen J, Jørgensen M. A comprehensive analysis of pneumococcal two-component system regulatory networks. NAR Genom Bioinform 2024; 6:lqae039. [PMID: 38650915 PMCID: PMC11034029 DOI: 10.1093/nargab/lqae039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 04/04/2024] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Abstract
Two-component systems are key signal-transduction systems that enable bacteria to respond to a wide variety of environmental stimuli. The human pathogen, Streptococcus pneumoniae (pneumococcus) encodes 13 two-component systems and a single orphan response regulator, most of which are significant for pneumococcal pathogenicity. Mapping the regulatory networks governed by these systems is key to understand pneumococcal host adaptation. Here we employ a novel bioinformatic approach to predict the regulons of each two-component system based on publicly available whole-genome sequencing data. By employing pangenome-wide association studies (panGWAS) to predict genotype-genotype associations for each two-component system, we predicted regulon genes of 11 of the pneumococcal two-component systems. Through validation via next-generation RNA-sequencing on response regulator overexpression mutants, several top candidate genes predicted by the panGWAS analysis were confirmed as regulon genes. The present study presents novel details on multiple pneumococcal two-component systems, including an expansion of regulons, identification of candidate response regulator binding motifs, and identification of candidate response regulator-regulated small non-coding RNAs. We also demonstrate a use for panGWAS as a complementary tool in target gene identification via identification of genotype-to-genotype links. Expanding our knowledge on two-component systems in pathogens is crucial to understanding how these bacteria sense and respond to their host environment, which could prove useful in future drug development.
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Affiliation(s)
- Jens Sivkær Pettersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Flemming Damgaard Nielsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark
| | | | - Jakob Møller-Jensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Mikkel Girke Jørgensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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3
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Savitskaya A, Masso-Silva J, Haddaoui I, Enany S. Exploring the arsenal of antimicrobial peptides: Mechanisms, diversity, and applications. Biochimie 2023; 214:216-227. [PMID: 37499896 DOI: 10.1016/j.biochi.2023.07.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 07/09/2023] [Accepted: 07/24/2023] [Indexed: 07/29/2023]
Abstract
Antimicrobial peptides (AMPs) are essential for defence against pathogens in all living organisms and possessed activities against bacteria, fungi, viruses, parasites and even cancer cells. AMPs are short peptides containing 12-100 amino acids conferring a net positive charge and an amphiphilic property in most cases. Although, anionic AMPs also exist. AMPs can be classified based on the types of secondary structures, charge, hydrophobicity, amino acid composition, length, etc. Their mechanism of action usually includes a membrane disruption process through pore formation (three different models have been described, barrel-stave, toroidal or carpet model) but AMPs can also penetrate and impair intracellular functions. Besides their activity against pathogens, they have also shown immunomodulatory properties in complex scenarios through many different interactions. The aim of this review to summarize knowledge about AMP's and discuss the potential application of AMPs as therapeutics, the challenges due to their limitations, including their susceptibility to degradation, the potential generation of AMP resistance, cost, etc. We also discuss the current FDA-approved drugs based on AMPs and strategies to circumvent natural AMPs' limitations.
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Affiliation(s)
- Anna Savitskaya
- Institute of Bioorganic Chemistry of Russian Academy of Science, Moscow, Russian Federation
| | - Jorge Masso-Silva
- Division of Pulmonary, Critical Care, Sleep Medicine and Physiology, University of California San Diego, La Jolla, CA, USA
| | - Imen Haddaoui
- National Research Institute of Rural Engineering, Water and Forestry, University of Carthage, LR Valorization of Unconventional Waters, Ariana, Tunisia
| | - Shymaa Enany
- Microbiology and Immunology Department, Faculty of Pharmacy, Suez Canal University, Ismailia, Egypt; Biomedical Research Department, Armed Force College of Medicine, Cairo, Egypt.
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4
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Wei Y, Sturges CI, Palmer KL. Human Serum Supplementation Promotes Streptococcus mitis Growth and Induces Specific Transcriptomic Responses. Microbiol Spectr 2023; 11:e0512922. [PMID: 37014220 PMCID: PMC10269507 DOI: 10.1128/spectrum.05129-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/01/2023] [Indexed: 04/05/2023] Open
Abstract
Streptococcus mitis is a normal member of the human oral microbiota and a leading opportunistic pathogen causing infective endocarditis (IE). Despite the complex interactions between S. mitis and the human host, understanding of S. mitis physiology and its mechanisms of adaptation to host-associated environments is inadequate, especially compared with other IE bacterial pathogens. This study reports the growth-promoting effects of human serum on S. mitis and other pathogenic streptococci, including S. oralis, S. pneumoniae, and S. agalactiae. Using transcriptomic analyses, we identified that, with the addition of human serum, S. mitis downregulates uptake systems for metal ions and sugars, fatty acid biosynthetic genes, and genes involved in stress response and other processes related with growth and replication. S. mitis upregulates uptake systems for amino acids and short peptides in response to human serum. Zinc availability and environmental signals sensed by the induced short peptide binding proteins were not sufficient to confer the growth-promoting effects. More investigation is required to establish the mechanism for growth promotion. Overall, our study contributes to the fundamental understanding of S. mitis physiology under host-associated conditions. IMPORTANCE S. mitis is exposed to human serum components during commensalism in the human mouth and bloodstream pathogenesis. However, the physiological effects of serum components on this bacterium remain unclear. Using transcriptomic analyses, S. mitis biological processes that respond to the presence of human serum were revealed, improving the fundamental understanding of S. mitis physiology in human host conditions.
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Affiliation(s)
- Yahan Wei
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Camille I. Sturges
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Kelli L. Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
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5
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A Genome-Wide CRISPR Interference Screen Reveals an StkP-Mediated Connection between Cell Wall Integrity and Competence in Streptococcus salivarius. mSystems 2022; 7:e0073522. [PMID: 36342134 PMCID: PMC9765292 DOI: 10.1128/msystems.00735-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Competence is one of the most efficient bacterial evolutionary and adaptative strategies by synchronizing production of antibacterial compounds and integration of DNA released by dead cells. In most streptococci, this tactic is orchestrated by the ComRS system, a pheromone communication device providing a short time window of activation in which only part of the population is responsive. Understanding how this developmental process integrates multiple inputs to fine-tune the adequate response is a long-standing question. However, essential genes involved in the regulation of ComRS have been challenging to study. In this work, we built a conditional mutant library using CRISPR interference and performed three complementary screens to investigate competence genetic regulation in the human commensal Streptococcus salivarius. We show that initiation of competence increases upon cell wall impairment, suggesting a connection between cell envelope stress and competence activation. Notably, we report a key role for StkP, a serine-threonine kinase known to regulate cell wall homeostasis. We show that StkP controls competence by a mechanism that reacts to peptidoglycan fragments. Together, our data suggest a key cell wall sensing mechanism coupling competence to cell envelope integrity. IMPORTANCE Survival of human commensal streptococci in the digestive tract requires efficient strategies which must be tightly and collectively controlled for responding to competitive pressure and drastic environmental changes. In this context, the autocrine signaling system ComRS controlling competence for natural transformation and predation in salivarius streptococci could be seen as a multi-input device integrating a variety of environmental stimuli. In this work, we revealed novel positive and negative competence modulators by using a genome-wide CRISPR interference strategy. Notably, we highlighted an unexpected connection between bacterial envelope integrity and competence activation that involves several cell wall sensors. Together, these results showcase how commensal streptococci can fine-tune the pheromone-based competence system by responding to multiple inputs affecting their physiological status in order to calibrate an appropriate collective behavior.
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Diagne AM, Pelletier A, Durmort C, Faure A, Kanonenberg K, Freton C, Page A, Delolme F, Vorac J, Vallet S, Bellard L, Vivès C, Fieschi F, Vernet T, Rousselle P, Guiral S, Grangeasse C, Jault JM, Orelle C. Identification of a two-component regulatory system involved in antimicrobial peptide resistance in Streptococcus pneumoniae. PLoS Pathog 2022; 18:e1010458. [PMID: 35395062 PMCID: PMC9020739 DOI: 10.1371/journal.ppat.1010458] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 04/20/2022] [Accepted: 03/18/2022] [Indexed: 11/24/2022] Open
Abstract
Two-component regulatory systems (TCS) are among the most widespread mechanisms that bacteria use to sense and respond to environmental changes. In the human pathogen Streptococcus pneumoniae, a total of 13 TCS have been identified and many of them have been linked to pathogenicity. Notably, TCS01 strongly contributes to pneumococcal virulence in several infection models. However, it remains one of the least studied TCS in pneumococci and its functional role is still unclear. In this study, we demonstrate that TCS01 cooperates with a BceAB-type ABC transporter to sense and induce resistance to structurally-unrelated antimicrobial peptides of bacterial origin that all target undecaprenyl-pyrophosphate or lipid II, which are essential precursors of cell wall biosynthesis. Even though tcs01 and bceAB genes do not locate in the same gene cluster, disruption of either of them equally sensitized the bacterium to the same set of antimicrobial peptides. We show that the key function of TCS01 is to upregulate the expression of the transporter, while the latter appears the main actor in resistance. Electrophoretic mobility shift assays further demonstrated that the response regulator of TCS01 binds to the promoter region of the bceAB genes, implying a direct control of these genes. The BceAB transporter was overexpressed and purified from E. coli. After reconstitution in liposomes, it displayed substantial ATPase and GTPase activities that were stimulated by antimicrobial peptides to which it confers resistance to, revealing new functional features of a BceAB-type transporter. Altogether, this inducible defense mechanism likely contributes to the survival of the opportunistic microorganism in the human host, in which competition among commensal microorganisms is a key determinant for effective host colonization and invasive path.
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Affiliation(s)
- Aissatou Maty Diagne
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Anaïs Pelletier
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Claire Durmort
- Institute of Structural Biology (IBS), UMR 5075 CNRS/University of Grenoble-Alpes, Grenoble, France
| | - Agathe Faure
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Kerstin Kanonenberg
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Céline Freton
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Adeline Page
- Protein Science Facility, SFR BioSciences, CNRS, UMS3444, INSERM US8, University of Lyon, Lyon, France
| | - Frédéric Delolme
- Protein Science Facility, SFR BioSciences, CNRS, UMS3444, INSERM US8, University of Lyon, Lyon, France
| | - Jaroslav Vorac
- Institute of Structural Biology (IBS), UMR 5075 CNRS/University of Grenoble-Alpes, Grenoble, France
| | - Sylvain Vallet
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Laure Bellard
- Institute of Structural Biology (IBS), UMR 5075 CNRS/University of Grenoble-Alpes, Grenoble, France
| | - Corinne Vivès
- Institute of Structural Biology (IBS), UMR 5075 CNRS/University of Grenoble-Alpes, Grenoble, France
| | - Franck Fieschi
- Institute of Structural Biology (IBS), UMR 5075 CNRS/University of Grenoble-Alpes, Grenoble, France
| | - Thierry Vernet
- Institute of Structural Biology (IBS), UMR 5075 CNRS/University of Grenoble-Alpes, Grenoble, France
| | - Patricia Rousselle
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique (LBTI), UMR 5305 CNRS/University of Lyon, Lyon, France
| | - Sébastien Guiral
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Christophe Grangeasse
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Jean-Michel Jault
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
| | - Cédric Orelle
- Molecular Microbiology and Structural Biochemistry (MMSB), UMR 5086 CNRS/University of Lyon, Lyon, France
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7
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Abstract
RNases perform indispensable functions in regulating gene expression in many bacterial pathogens by processing and/or degrading RNAs. Despite the pivotal role of RNases in regulating bacterial virulence factors, the functions of RNases have not yet been studied in the major human respiratory pathogen Streptococcus pneumoniae (pneumococcus). Here, we sought to determine the impact of two conserved RNases, the endoribonuclease RNase Y and exoribonuclease polynucleotide phosphorylase (PNPase), on the physiology and virulence of S. pneumoniae serotype 2 strain D39. We report that RNase Y and PNPase are essential for pneumococcal pathogenesis, as both deletion mutants showed strong attenuation of virulence in murine models of invasive pneumonia. Genome-wide transcriptomic analysis revealed that the abundances of nearly 200 mRNA transcripts were significantly increased, whereas those of several pneumococcal small regulatory RNAs (sRNAs), including the Ccn (CiaR-controlled noncoding RNA) sRNAs, were altered in the Δrny mutant relative to the wild-type strain. Additionally, lack of RNase Y resulted in pleiotropic phenotypes that included defects in pneumococcal cell morphology and growth in vitro. In contrast, Δpnp mutants showed no growth defect in vitro but differentially expressed a total of 40 transcripts, including the tryptophan biosynthesis operon genes and numerous 5' cis-acting regulatory RNAs, a majority of which were previously shown to impact pneumococcal disease progression in mice using the serotype 4 strain TIGR4. Together, our data suggest that RNase Y exerts a global impact on pneumococcal physiology, while PNPase mediates virulence phenotypes, likely through sRNA regulation. IMPORTANCE Streptococcus pneumoniae is a notorious human pathogen that adapts to conditions in distinct host tissues and responds to host cell interactions by adjusting gene expression. RNases are key players that modulate gene expression by mediating the turnover of regulatory and protein-coding transcripts. Here, we characterized two highly conserved RNases, RNase Y and PNPase, and evaluated their impact on the S. pneumoniae transcriptome for the first time. We show that PNPase influences the levels of a narrow set of mRNAs but a large number of regulatory RNAs primarily implicated in virulence control, whereas RNase Y has a more sweeping effect on gene expression, altering levels of transcripts involved in diverse cellular processes, including cell division, metabolism, stress response, and virulence. This study further reveals that RNase Y regulates expression of genes governing competence by mediating the turnover of CiaR-controlled noncoding (Ccn) sRNAs.
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8
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Lannes-Costa PS, de Oliveira JSS, da Silva Santos G, Nagao PE. A current review of pathogenicity determinants of Streptococcus sp. J Appl Microbiol 2021; 131:1600-1620. [PMID: 33772968 DOI: 10.1111/jam.15090] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/16/2021] [Accepted: 03/24/2021] [Indexed: 12/16/2022]
Abstract
The genus Streptococcus comprises important pathogens, many of them are part of the human or animal microbiota. Advances in molecular genetics, taxonomic approaches and phylogenomic studies have led to the establishment of at least 100 species that have a severe impact on human health and are responsible for substantial economic losses to agriculture. The infectivity of the pathogens is linked to cell-surface components and/or secreted virulence factors. Bacteria have evolved sophisticated and multifaceted adaptation strategies to the host environment, including biofilm formation, survival within professional phagocytes, escape the host immune response, amongst others. This review focuses on virulence mechanism and zoonotic potential of Streptococcus species from pyogenic (S. agalactiae, S. pyogenes) and mitis groups (S. pneumoniae).
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Affiliation(s)
- P S Lannes-Costa
- Laboratory of Molecular Biology and Physiology of Streptococci, Institute of Biology Roberto Alcantara Gomes, Rio de Janeiro State University (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - J S S de Oliveira
- Laboratory of Molecular Biology and Physiology of Streptococci, Institute of Biology Roberto Alcantara Gomes, Rio de Janeiro State University (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - G da Silva Santos
- Laboratory of Molecular Biology and Physiology of Streptococci, Institute of Biology Roberto Alcantara Gomes, Rio de Janeiro State University (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - P E Nagao
- Laboratory of Molecular Biology and Physiology of Streptococci, Institute of Biology Roberto Alcantara Gomes, Rio de Janeiro State University (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
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9
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Bradshaw JL, Rafiqullah IM, Robinson DA, McDaniel LS. Transformation of nonencapsulated Streptococcus pneumoniae during systemic infection. Sci Rep 2020; 10:18932. [PMID: 33144660 PMCID: PMC7641166 DOI: 10.1038/s41598-020-75988-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/16/2020] [Indexed: 11/24/2022] Open
Abstract
Streptococcus pneumoniae (pneumococcus) is a principal cause of bacterial middle ear infections, pneumonia, and meningitis. Capsule-targeted pneumococcal vaccines have likely contributed to increased carriage of nonencapsulated S. pneumoniae (NESp). Some NESp lineages are associated with highly efficient DNA uptake and transformation frequencies. However, NESp strains lack capsule that may increase disease severity. We tested the hypothesis that NESp could acquire capsule during systemic infection and transform into more virulent pneumococci. We reveal that NESp strains MNZ67 and MNZ41 are highly transformable and resistant to multiple antibiotics. Natural transformation of NESp when co-administered with heat-killed encapsulated strain WU2 in a murine model of systemic infection resulted in encapsulation of NESp and increased virulence during bacteremia. Functional capsule production increased the pathogenic potential of MNZ67 by significantly decreasing complement deposition on the bacterial surface. However, capsule acquisition did not further decrease complement deposition on the relatively highly pathogenic strain MNZ41. Whole genome sequencing of select transformants demonstrated that recombination of up to 56.7 kbp length occurred at the capsule locus, along with additional recombination occurring at distal sites harboring virulence-associated genes. These findings indicate NESp can compensate for lack of capsule production and rapidly evolve into more virulent strains.
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Affiliation(s)
- Jessica L Bradshaw
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Iftekhar M Rafiqullah
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, MS, USA
| | - D Ashley Robinson
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, MS, USA
| | - Larry S McDaniel
- Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, MS, USA.
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Two-Component Signal Transduction Systems in the Human Pathogen Streptococcus agalactiae. Infect Immun 2020; 88:IAI.00931-19. [PMID: 31988177 DOI: 10.1128/iai.00931-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Streptococcus agalactiae (group B Streptococcus [GBS]) is an important cause of invasive infection in newborns, maternal women, and older individuals with underlying chronic illnesses. GBS has many mechanisms to adapt and survive in its host, and these mechanisms are often controlled via two-component signal transduction systems. In GBS, more than 20 distinct two-component systems (TCSs) have been classified to date, consisting of canonical TCSs as well as orphan and atypical sensors and regulators. These signal transducing systems are necessary for metabolic regulation, resistance to antibiotics and antimicrobials, pathogenesis, and adhesion to the mucosal surfaces to colonize the host. This minireview discusses the structures of these TCSs in GBS as well as how selected systems regulate essential cellular processes such as survival and colonization. GBS contains almost double the number of TCSs compared to the closely related Streptococcus pyogenes and Streptococcus pneumoniae, and while research on GBS TCSs has been increasing in recent years, no comprehensive reviews of these TCSs exist, making this review especially relevant.
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11
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Ganguly T, Kajfasz JK, Abranches J, Lemos JA. Regulatory circuits controlling Spx levels in Streptococcus mutans. Mol Microbiol 2020; 114:109-126. [PMID: 32189382 DOI: 10.1111/mmi.14499] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 03/13/2020] [Accepted: 03/14/2020] [Indexed: 02/01/2023]
Abstract
Spx is a major regulator of stress responses in Firmicutes. In Streptococcus mutans, two Spx homologues, SpxA1 and SpxA2, were identified as mediators of oxidative stress responses but the regulatory circuits controlling their levels and activity are presently unknown. Comparison of SpxA1 and SpxA2 protein sequences revealed differences at the C-terminal end, with SpxA1 containing an unusual number of acidic residues. Here, we showed that a green fluorescence protein (GFP) reporter becomes unstable when fused to the last 10 amino acids of SpxA2 but remained stable when fused to the C-terminal acidic tail of SpxA1. Inactivation of clpP or simultaneous inactivation of clpC and clpE stabilized the GFP::SpxA2tail fusion protein. Addition of acidic amino acids to the GFP::SpxA2tail chimera stabilized GFP, while deletion of the acidic residues destabilized GFP::SpxA1tail . Promoter reporter fusions revealed that spxA1 transcription is co-repressed by the metalloregulators PerR and SloR while spxA2 transcription is largely dependent on the envelope stress regulator LiaFSR. In agreement with spxA2 being part of the LiaR regulon, SpxA2 was found to be critical for the growth of S. mutans under envelope stress conditions. Finally, we showed that redox sensing is essential for SpxA1-dependent activation of oxidative stress responses but dispensable for SpxA2-mediated envelope stress responses.
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Affiliation(s)
- Tridib Ganguly
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Jessica K Kajfasz
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Jacqueline Abranches
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - José A Lemos
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
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12
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Wang J, Li JW, Li J, Huang Y, Wang S, Zhang JR. Regulation of pneumococcal epigenetic and colony phases by multiple two-component regulatory systems. PLoS Pathog 2020; 16:e1008417. [PMID: 32187228 PMCID: PMC7105139 DOI: 10.1371/journal.ppat.1008417] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 03/30/2020] [Accepted: 02/19/2020] [Indexed: 11/19/2022] Open
Abstract
Streptococcus pneumoniae is well known for phase variation between opaque (O) and transparent (T) colonies within clonal populations. While the O variant is specialized in invasive infection (with a thicker capsule and higher resistance to host clearance), the T counterpart possesses a relatively thinner capsule and thereby higher airway adherence and colonization. Our previous study found that phase variation is caused by reversible switches of the "opaque ON-or-OFF" methylomes or methylation patterns of pneumococcal genome, which is dominantly driven by the PsrA-catalyzed inversions of the DNA methyltransferase hsdS genes. This study revealed that switch frequency between the O and T variants is regulated by five transcriptional response regulators (rr) of the two-component systems (TCSs). The mutants of rr06, rr08, rr09, rr11 and rr14 produced significantly fewer O and more T colonies. Further mutagenesis revealed that RR06, RR08, RR09 and RR11 enrich the O variant by modulating the directions of the PsrA-catalyzed inversion reactions. In contrast, the impact of RR14 (RitR) on phase variation is independent of PsrA. Consistently, SMRT sequencing uncovered significantly diminished "opaque ON" methylome in the mutants of rr06, rr08, rr09 and rr11 but not that of rr14. Lastly, the phosphorylated form of RR11 was shown to activate the transcription of comW and two sugar utilization systems that are necessary for maintenance of the "opaque ON" genotype and phenotype. This work has thus uncovered multiple novel mechanisms that balance pneumococcal epigenetic status and physiology.
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Affiliation(s)
- Juanjuan Wang
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Jing-Wen Li
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Jing Li
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Yijia Huang
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Shaomeng Wang
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Jing-Ren Zhang
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
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Electronic Cigarette (E-Cigarette) Vapor Exposure Alters the Streptococcus pneumoniae Transcriptome in a Nicotine-Dependent Manner without Affecting Pneumococcal Virulence. Appl Environ Microbiol 2020; 86:AEM.02125-19. [PMID: 31791951 DOI: 10.1128/aem.02125-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 11/12/2019] [Indexed: 12/25/2022] Open
Abstract
The effects of electronic cigarette (e-cigarette) vapor (EV) exposure on the physiology of respiratory microflora are not fully defined. We analyzed the effects of exposure to vapor from nicotine-containing and nicotine-free e-liquid formulations on the virulence and transcriptome of Streptococcus pneumoniae strain TIGR4, a pathogen that asymptomatically colonizes the human nasopharyngeal mucosa. TIGR4 was preexposed for 2 h to nicotine-containing EV extract (EVE+NIC), nicotine-free EV extract (EVE-NIC), cigarette smoke extract (CSE), or nutrient-rich tryptic soy (TS) broth (control). The differences between the treatment and control strains were explored using transcriptome sequencing (RNA sequencing [RNA-Seq]), in vitro virulence assays, and an in vivo mouse model of acute pneumonia. The analysis of RNA-Seq profiles revealed modest changes in the expression of 14 genes involved in sugar transport and metabolism in EVE-NIC-preexposed TIGR4 compared to the control, while EVE+NIC or CSE exposure altered expression of 264 and 982 genes, respectively, most of which were involved in metabolism and stress response. Infection in a mouse model of acute pneumonia with control TIGR4 or with TIGR4 preexposed to EVE+NIC, EVE-NIC, or CSE did not show significant differences in disease parameters, such as bacterial organ burden and respiratory cytokine response. Interestingly, TIGR4 exposed to CSE or EVE+NIC (but not EVE-NIC) exhibited moderate induction of biofilm formation. However, none of the treatment groups showed significant alterations in pneumococcal hydrophobicity or epithelial cell adherence. In summary, our study reports that exposure to EV significantly alters the S. pneumoniae transcriptome in a nicotine-dependent manner without affecting pneumococcal virulence.IMPORTANCE With the increasing popularity of e-cigarettes among cigarette smoking and nonsmoking adults and children and the recent reports of vaping-related lung illness and deaths, further analysis of the adverse health effects of e-cigarette vapor (EV) exposure is warranted. Since pathogenic bacteria such as Streptococcus pneumoniae can colonize the human nasopharynx as commensals, they may be affected by exposure to bioactive chemicals in EV. Hence, in this study we examined the effects of EV exposure on the physiology of S. pneumoniae strain TIGR4. In order to differentiate between the effects of nicotine and nonnicotine components, we specifically compared the RNA-Seq profiles and virulence of TIGR4 exposed to vapor from nicotine-containing and nicotine-free e-liquid formulations. We observed that nicotine-containing EV augmented TIGR4 biofilms and altered expression of TIGR4 genes predominantly involved in metabolism and stress response. However, neither nicotine-containing nor nicotine-free EV affected TIGR4 virulence in a mouse model.
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Winkler ME, Morrison DA. Competence beyond Genes: Filling in the Details of the Pneumococcal Competence Transcriptome by a Systems Approach. J Bacteriol 2019; 201:e00238-19. [PMID: 30988030 PMCID: PMC6560134 DOI: 10.1128/jb.00238-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
DNA uptake by natural competence is a central process underlying the genetic plasticity, biology, and virulence of the human respiratory opportunistic pathogen Streptococcus pneumoniae A study reported in this issue (J. Slager, R. Aprianto, and J.-W. Veening, J. Bacteriol. 201:e00780-18, https://doi.org/10.1128/JB.00780-18) combined deep-genome annotation and high-resolution transcriptome analyses to considerably extend the previous model of temporal regulation of competence at the operon and component gene levels. That extended study also provides a playbook for updating, refining, and extending genomic data sets and making them publicly available.
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Affiliation(s)
- Malcolm E Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Donald A Morrison
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
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Refining the Pneumococcal Competence Regulon by RNA Sequencing. J Bacteriol 2019; 201:JB.00780-18. [PMID: 30885934 PMCID: PMC6560143 DOI: 10.1128/jb.00780-18] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 03/15/2019] [Indexed: 12/13/2022] Open
Abstract
Streptococcus pneumoniae is an opportunistic human pathogen responsible for over a million deaths every year. Although both vaccination programs and antibiotic therapies have been effective in prevention and treatment of pneumococcal infections, respectively, the sustainability of these solutions is uncertain. The pneumococcal genome is highly flexible, leading to vaccine escape and antibiotic resistance. This flexibility is predominantly facilitated by competence, a state allowing the cell to take up and integrate exogenous DNA. Thus, it is essential to obtain a detailed overview of gene expression during competence. This is stressed by the fact that administration of several classes of antibiotics can lead to competence. Previous studies on the competence regulon were performed with microarray technology and were limited to an incomplete set of known genes. Using RNA sequencing combined with an up-to-date genome annotation, we provide an updated overview of competence-regulated genes. Competence for genetic transformation allows the opportunistic human pathogen Streptococcus pneumoniae to take up exogenous DNA for incorporation into its own genome. This ability may account for the extraordinary genomic plasticity of this bacterium, leading to antigenic variation, vaccine escape, and the spread of antibiotic resistance. The competence system has been thoroughly studied, and its regulation is well understood. Additionally, over the last decade, several stress factors have been shown to trigger the competent state, leading to the activation of several stress response regulons. The arrival of next-generation sequencing techniques allowed us to update the competence regulon, the latest report on which still depended on DNA microarray technology. Enabled by the availability of an up-to-date genome annotation, including transcript boundaries, we assayed time-dependent expression of all annotated features in response to competence induction, were able to identify the affected promoters, and produced a more complete overview of the various regulons activated during the competence state. We show that 4% of all annotated genes are under direct control of competence regulators ComE and ComX, while the expression of a total of up to 17% of all genes is affected, either directly or indirectly. Among the affected genes are various small RNAs with an as-yet-unknown function. Besides the ComE and ComX regulons, we were also able to refine the CiaR, VraR (LiaR), and BlpR regulons, underlining the strength of combining transcriptome sequencing (RNA-seq) with a well-annotated genome. IMPORTANCEStreptococcus pneumoniae is an opportunistic human pathogen responsible for over a million deaths every year. Although both vaccination programs and antibiotic therapies have been effective in prevention and treatment of pneumococcal infections, respectively, the sustainability of these solutions is uncertain. The pneumococcal genome is highly flexible, leading to vaccine escape and antibiotic resistance. This flexibility is predominantly facilitated by competence, a state allowing the cell to take up and integrate exogenous DNA. Thus, it is essential to obtain a detailed overview of gene expression during competence. This is stressed by the fact that administration of several classes of antibiotics can lead to competence. Previous studies on the competence regulon were performed with microarray technology and were limited to an incomplete set of known genes. Using RNA sequencing combined with an up-to-date genome annotation, we provide an updated overview of competence-regulated genes.
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Streptococcus pneumoniae two-component regulatory systems: The interplay of the pneumococcus with its environment. Int J Med Microbiol 2018; 308:722-737. [DOI: 10.1016/j.ijmm.2017.11.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/21/2017] [Accepted: 11/24/2017] [Indexed: 02/06/2023] Open
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17
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Contribution of YthA, a PspC Family Transcriptional Regulator of Lactococcus lactis F44 Acid Tolerance and Nisin Yield: a Transcriptomic Approach. Appl Environ Microbiol 2018. [PMID: 29305506 DOI: 10.1128/aem.02483-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
To overcome the adverse impacts of environmental stresses during growth, different adaptive regulation mechanisms can be activated in Lactococcus lactis In this study, the transcription levels of eight transcriptional regulators of L. lactis subsp. lactis F44 under acid stress were analyzed using quantitative reverse transcription-PCR. Eight gene-overexpressing strains were then constructed to examine their influences on acid-resistant capability. Overexpressing ythA, a PspC family transcriptional regulator, increased the survival rate by 3.2-fold compared to the control at the lethal pH 3.0 acid shock. Moreover, the nisin yield was increased by 45.50%. The ythA-overexpressing strain FythA appeared to have higher intracellular pH stability and nisin-resistant ability. Subsequently, transcriptome analysis revealed that the vast majority of genes associated with amino acid biosynthesis, including arginine, serine, phenylalanine, and tyrosine, were predominantly upregulated in FythA. Arginine biosynthesis (argG and argH), arginine deiminase pathway, and polar amino acid transport (ysfE and ysfF) were proposed to be the main regulation mechanisms of YthA. Furthermore, the transcription of genes associated with pyrimidine and exopolysaccharide biosynthesis were upregulated. The transcriptional levels of nisIPRKFEG genes were substantially higher in FythA, which directly contributed to the yield and resistance of nisin. Three potential DNA-binding sequences were predicted by computer analysis using the upstream regions of genes with prominent changes. This study showed that YthA could increase acid resistance and nisin yield and revealed a putative regulation mechanism of YthA.IMPORTANCE Nisin, produced by Lactococcus lactis subsp. lactis, is widely used as a safe food preservative. Acid stress becomes the primary restrictive factor of cell growth and nisin yield. In this research, we found that the transcriptional regulator YthA was conducive to enhancing the acid resistance of L. lactis F44. Overexpressing ythA could significantly improve the survival rate and nisin yield. The stability of intracellular pH and nisin resistance were also increased. Transcriptome analysis showed that nisin immunity and the biosynthesis of some amino acids, pyrimidine, and exopolysaccharides were enhanced in the engineered strain. This study elucidates the regulation mechanism of YthA and provides a novel strategy for constructing robust industrial L. lactis strains.
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Contribution of YthA, a PspC Family Transcriptional Regulator of Lactococcus lactis F44 Acid Tolerance and Nisin Yield: a Transcriptomic Approach. Appl Environ Microbiol 2018; 84:AEM.02483-17. [PMID: 29305506 DOI: 10.1128/aem.02483-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 12/22/2017] [Indexed: 11/20/2022] Open
Abstract
To overcome the adverse impacts of environmental stresses during growth, different adaptive regulation mechanisms can be activated in Lactococcus lactis In this study, the transcription levels of eight transcriptional regulators of L. lactis subsp. lactis F44 under acid stress were analyzed using quantitative reverse transcription-PCR. Eight gene-overexpressing strains were then constructed to examine their influences on acid-resistant capability. Overexpressing ythA, a PspC family transcriptional regulator, increased the survival rate by 3.2-fold compared to the control at the lethal pH 3.0 acid shock. Moreover, the nisin yield was increased by 45.50%. The ythA-overexpressing strain FythA appeared to have higher intracellular pH stability and nisin-resistant ability. Subsequently, transcriptome analysis revealed that the vast majority of genes associated with amino acid biosynthesis, including arginine, serine, phenylalanine, and tyrosine, were predominantly upregulated in FythA. Arginine biosynthesis (argG and argH), arginine deiminase pathway, and polar amino acid transport (ysfE and ysfF) were proposed to be the main regulation mechanisms of YthA. Furthermore, the transcription of genes associated with pyrimidine and exopolysaccharide biosynthesis were upregulated. The transcriptional levels of nisIPRKFEG genes were substantially higher in FythA, which directly contributed to the yield and resistance of nisin. Three potential DNA-binding sequences were predicted by computer analysis using the upstream regions of genes with prominent changes. This study showed that YthA could increase acid resistance and nisin yield and revealed a putative regulation mechanism of YthA.IMPORTANCE Nisin, produced by Lactococcus lactis subsp. lactis, is widely used as a safe food preservative. Acid stress becomes the primary restrictive factor of cell growth and nisin yield. In this research, we found that the transcriptional regulator YthA was conducive to enhancing the acid resistance of L. lactis F44. Overexpressing ythA could significantly improve the survival rate and nisin yield. The stability of intracellular pH and nisin resistance were also increased. Transcriptome analysis showed that nisin immunity and the biosynthesis of some amino acids, pyrimidine, and exopolysaccharides were enhanced in the engineered strain. This study elucidates the regulation mechanism of YthA and provides a novel strategy for constructing robust industrial L. lactis strains.
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Kleine B, Chattopadhyay A, Polen T, Pinto D, Mascher T, Bott M, Brocker M, Freudl R. The three-component system EsrISR regulates a cell envelope stress response in Corynebacterium glutamicum. Mol Microbiol 2017; 106:719-741. [PMID: 28922502 DOI: 10.1111/mmi.13839] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2017] [Indexed: 02/03/2023]
Abstract
When the cell envelope integrity is compromised, bacteria trigger signaling cascades resulting in the production of proteins that counteract these extracytoplasmic stresses. Here, we show that the two-component system EsrSR regulates a cell envelope stress response in the Actinobacterium Corynebacterium glutamicum. The sensor kinase EsrS possesses an amino-terminal phage shock protein C (PspC) domain, a property that sets EsrSR apart from all other two-component systems characterized so far. An integral membrane protein, EsrI, whose gene is divergently transcribed to the esrSR gene locus and which interestingly also possesses a PspC domain, acts as an inhibitor of EsrSR under non-stress conditions. The resulting EsrISR three-component system is activated among others by antibiotics inhibiting the lipid II cycle, such as bacitracin and vancomycin, and it orchestrates a broad regulon including the esrI-esrSR gene locus itself, genes encoding heat shock proteins, ABC transporters, and several putative membrane-associated or secreted proteins of unknown function. Among those, the ABC transporter encoded by cg3322-3320 was shown to be directly involved in bacitracin resistance of C. glutamicum. Since similar esrI-esrSR loci are present in a large number of actinobacterial genomes, EsrISR represents a novel type of stress-responsive system whose components are highly conserved in the phylum Actinobacteria.
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Affiliation(s)
- Britta Kleine
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Ava Chattopadhyay
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Tino Polen
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Daniela Pinto
- Institut für Mikrobiologie, Technische Universität Dresden, Zellescher Weg 20b, Dresden D-01217, Germany
| | - Thorsten Mascher
- Institut für Mikrobiologie, Technische Universität Dresden, Zellescher Weg 20b, Dresden D-01217, Germany
| | - Michael Bott
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Melanie Brocker
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
| | - Roland Freudl
- Institut für Bio- und Geowissenschaften 1, Biotechnologie, Forschungszentrum Jülich GmbH, Jülich D-52425, Germany
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20
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Roobthaisong A, Aikawa C, Nozawa T, Maruyama F, Nakagawa I. YvqE and CovRS of Group A Streptococcus Play a Pivotal Role in Viability and Phenotypic Adaptations to Multiple Environmental Stresses. PLoS One 2017; 12:e0170612. [PMID: 28122066 PMCID: PMC5266302 DOI: 10.1371/journal.pone.0170612] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 01/06/2017] [Indexed: 01/14/2023] Open
Abstract
Streptococcus pyogenes (group A Streptococcus, or GAS) is a human pathogen that causes a wide range of diseases. For successful colonization within a variety of host niches, GAS utilizes TCSs to sense and respond to environmental changes and adapts its pathogenic traits accordingly; however, many GAS TCSs and their interactions remain uncharacterized. Here, we elucidated the roles of a poorly characterized TCS, YvqEC, and a well-studied TCS, CovRS, in 2 different GAS strain SSI-1 and JRS4, respectively. Deletion of yvqE and yvqC in JRS4 resulted in lower cell viability and abnormality of cell division when compared to the wild-type strain under standard culture conditions, demonstrating an important role for YvqEC. Furthermore, a double-deletion of yvqEC and covRS in SSI-1 and JRS4 resulted in a significantly impaired ability to survive under various stress conditions, as well as an increased sensitivity to cell wall-targeting antibiotics compared to that observed in either single mutant or wild-type strains suggesting synergistic interactions. Our findings provide new insights into the impact of poorly characterized TCS (YvqEC) and potential synergistic interactions between YvqEC and CovRS and reveal their potential role as novel therapeutic targets against GAS infection.
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Affiliation(s)
- Amonrattana Roobthaisong
- Section of Molecular Craniofacial Embryology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
- Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Chihiro Aikawa
- Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takashi Nozawa
- Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Fumito Maruyama
- Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Ichiro Nakagawa
- Department of Microbiology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- * E-mail:
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Abstract
Lactic acid bacteria (LAB) are important starter, commensal, or pathogenic microorganisms. The stress physiology of LAB has been studied in depth for over 2 decades, fueled mostly by the technological implications of LAB robustness in the food industry. Survival of probiotic LAB in the host and the potential relatedness of LAB virulence to their stress resilience have intensified interest in the field. Thus, a wealth of information concerning stress responses exists today for strains as diverse as starter (e.g., Lactococcus lactis), probiotic (e.g., several Lactobacillus spp.), and pathogenic (e.g., Enterococcus and Streptococcus spp.) LAB. Here we present the state of the art for LAB stress behavior. We describe the multitude of stresses that LAB are confronted with, and we present the experimental context used to study the stress responses of LAB, focusing on adaptation, habituation, and cross-protection as well as on self-induced multistress resistance in stationary phase, biofilms, and dormancy. We also consider stress responses at the population and single-cell levels. Subsequently, we concentrate on the stress defense mechanisms that have been reported to date, grouping them according to their direct participation in preserving cell energy, defending macromolecules, and protecting the cell envelope. Stress-induced responses of probiotic LAB and commensal/pathogenic LAB are highlighted separately due to the complexity of the peculiar multistress conditions to which these bacteria are subjected in their hosts. Induction of prophages under environmental stresses is then discussed. Finally, we present systems-based strategies to characterize the "stressome" of LAB and to engineer new food-related and probiotic LAB with improved stress tolerance.
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Tran TT, Miller WR, Shamoo Y, Arias CA. Targeting cell membrane adaptation as a novel antimicrobial strategy. Curr Opin Microbiol 2016; 33:91-96. [PMID: 27458841 DOI: 10.1016/j.mib.2016.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 07/01/2016] [Accepted: 07/05/2016] [Indexed: 01/19/2023]
Abstract
Emergence of antibiotic resistance is an example of the incredible plasticity of bacteria to survive in all environments. The search for new antibiotics active against traditional targets is more challenging due not only to the lack of novel natural products to fulfill the current clinical needs against multidrug-resistant (MDR) bacteria, but also for the possible 'collateral' effects on the human microbiota. Thus, non-traditional approaches to combat MDR bacteria have been proposed. Here, we discuss the possibility of targeting the membrane response to the antibiotic attack (cell membrane adaptation) as a viable strategy to increase the activity of current antimicrobials, enhance the activity of the innate immune system and prevent development of resistance during therapy using the three-component regulatory system LiaFSR of enterococci as a model.
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Affiliation(s)
- Truc T Tran
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas McGovern Medical School, Houston, TX, United States; Center for Antibiotic Resistance and Microbial Genomics, University of Texas McGovern Medical School, Houston, TX, United States
| | - William R Miller
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas McGovern Medical School, Houston, TX, United States; Center for Antibiotic Resistance and Microbial Genomics, University of Texas McGovern Medical School, Houston, TX, United States
| | - Yousif Shamoo
- Department of Biochemistry and Cell Biology, Rice University, Houston, TX, United States
| | - Cesar A Arias
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas McGovern Medical School, Houston, TX, United States; Center for Antibiotic Resistance and Microbial Genomics, University of Texas McGovern Medical School, Houston, TX, United States; Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia; International Center for Microbial Genomics, Universidad El Bosque, Bogota, Colombia.
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Rashid R, Veleba M, Kline KA. Focal Targeting of the Bacterial Envelope by Antimicrobial Peptides. Front Cell Dev Biol 2016; 4:55. [PMID: 27376064 PMCID: PMC4894902 DOI: 10.3389/fcell.2016.00055] [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: 03/15/2016] [Accepted: 05/23/2016] [Indexed: 01/15/2023] Open
Abstract
Antimicrobial peptides (AMPs) are utilized by both eukaryotic and prokaryotic organisms. AMPs such as the human beta defensins, human neutrophil peptides, human cathelicidin, and many bacterial bacteriocins are cationic and capable of binding to anionic regions of the bacterial surface. Cationic AMPs (CAMPs) target anionic lipids [e.g., phosphatidylglycerol (PG) and cardiolipins (CL)] in the cell membrane and anionic components [e.g., lipopolysaccharide (LPS) and lipoteichoic acid (LTA)] of the cell envelope. Bacteria have evolved mechanisms to modify these same targets in order to resist CAMP killing, e.g., lysinylation of PG to yield cationic lysyl-PG and alanylation of LTA. Since CAMPs offer a promising therapeutic alternative to conventional antibiotics, which are becoming less effective due to rapidly emerging antibiotic resistance, there is a strong need to improve our understanding about the AMP mechanism of action. Recent literature suggests that AMPs often interact with the bacterial cell envelope at discrete foci. Here we review recent AMP literature, with an emphasis on focal interactions with bacteria, including (1) CAMP disruption mechanisms, (2) delocalization of membrane proteins and lipids by CAMPs, and (3) CAMP sensing systems and resistance mechanisms. We conclude with new approaches for studying the bacterial membrane, e.g., lipidomics, high resolution imaging, and non-detergent-based membrane domain extraction.
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Affiliation(s)
- Rafi Rashid
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University Singapore, Singapore
| | - Mark Veleba
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University Singapore, Singapore
| | - Kimberly A Kline
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University Singapore, Singapore
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Joo HS, Fu CI, Otto M. Bacterial strategies of resistance to antimicrobial peptides. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150292. [PMID: 27160595 PMCID: PMC4874390 DOI: 10.1098/rstb.2015.0292] [Citation(s) in RCA: 213] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2016] [Indexed: 02/06/2023] Open
Abstract
Antimicrobial peptides (AMPs) are a key component of the host's innate immune system, targeting invasive and colonizing bacteria. For successful survival and colonization of the host, bacteria have a series of mechanisms to interfere with AMP activity, and AMP resistance is intimately connected with the virulence potential of bacterial pathogens. In particular, because AMPs are considered as potential novel antimicrobial drugs, it is vital to understand bacterial AMP resistance mechanisms. This review gives a comparative overview of Gram-positive and Gram-negative bacterial strategies of resistance to various AMPs, such as repulsion or sequestration by bacterial surface structures, alteration of membrane charge or fluidity, degradation and removal by efflux pumps.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'.
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Affiliation(s)
- Hwang-Soo Joo
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), US National Institutes of Health (NIH), 50 South Drive, Bethesda, MD 20892, USA
| | - Chih-Iung Fu
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), US National Institutes of Health (NIH), 50 South Drive, Bethesda, MD 20892, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), US National Institutes of Health (NIH), 50 South Drive, Bethesda, MD 20892, USA
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Joo HS, Fu CI, Otto M. Bacterial strategies of resistance to antimicrobial peptides. Philos Trans R Soc Lond B Biol Sci 2016. [PMID: 27160595 DOI: 10.1098/rstb.2015.0292.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Antimicrobial peptides (AMPs) are a key component of the host's innate immune system, targeting invasive and colonizing bacteria. For successful survival and colonization of the host, bacteria have a series of mechanisms to interfere with AMP activity, and AMP resistance is intimately connected with the virulence potential of bacterial pathogens. In particular, because AMPs are considered as potential novel antimicrobial drugs, it is vital to understand bacterial AMP resistance mechanisms. This review gives a comparative overview of Gram-positive and Gram-negative bacterial strategies of resistance to various AMPs, such as repulsion or sequestration by bacterial surface structures, alteration of membrane charge or fluidity, degradation and removal by efflux pumps.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'.
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Affiliation(s)
- Hwang-Soo Joo
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), US National Institutes of Health (NIH), 50 South Drive, Bethesda, MD 20892, USA
| | - Chih-Iung Fu
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), US National Institutes of Health (NIH), 50 South Drive, Bethesda, MD 20892, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases (NIAID), US National Institutes of Health (NIH), 50 South Drive, Bethesda, MD 20892, USA
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Qin W, Wang L, Zhai R, Ma Q, Liu J, Bao C, Zhang H, Sun C, Feng X, Gu J, Du C, Han W, Langford PR, Lei L. Trimeric autotransporter adhesins contribute to Actinobacillus pleuropneumoniae pathogenicity in mice and regulate bacterial gene expression during interactions between bacteria and porcine primary alveolar macrophages. Antonie van Leeuwenhoek 2015; 109:51-70. [PMID: 26494209 DOI: 10.1007/s10482-015-0609-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 10/14/2015] [Indexed: 11/27/2022]
Abstract
Actinobacillus pleuropneumoniae is an important pathogen that causes respiratory disease in pigs. Trimeric autotransporter adhesin (TAA) is a recently discovered bacterial virulence factor that mediates bacterial adhesion and colonization. Two TAA coding genes have been found in the genome of A. pleuropneumoniae strain 5b L20, but whether they contribute to bacterial pathogenicity is unclear. In this study, we used homologous recombination to construct a double-gene deletion mutant, ΔTAA, in which both TAA coding genes were deleted and used it in in vivo and in vitro studies to confirm that TAAs participate in bacterial auto-aggregation, biofilm formation, cell adhesion and virulence in mice. A microarray analysis was used to determine whether TAAs can regulate other A. pleuropneumoniae genes during interactions with porcine primary alveolar macrophages. The results showed that deletion of both TAA coding genes up-regulated 36 genes, including ene1514, hofB and tbpB2, and simultaneously down-regulated 36 genes, including lgt, murF and ftsY. These data illustrate that TAAs help to maintain full bacterial virulence both directly, through their bioactivity, and indirectly by regulating the bacterial type II and IV secretion systems and regulating the synthesis or secretion of virulence factors. This study not only enhances our understanding of the role of TAAs but also has significance for those studying A. pleuropneumoniae pathogenesis.
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Affiliation(s)
- Wanhai Qin
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Lei Wang
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China.,College of Animal Science, Henan Institute of Science and Technology, Xinxiang, People's Republic of China
| | - Ruidong Zhai
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Qiuyue Ma
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Jianfang Liu
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Chuntong Bao
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Hu Zhang
- School of Public Health, Jilin University, Changchun, People's Republic of China
| | - Changjiang Sun
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Xin Feng
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Jingmin Gu
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Chongtao Du
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - Wenyu Han
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China
| | - P R Langford
- Section of Paediatrics, Imperial College London, London, UK
| | - Liancheng Lei
- College of Veterinary Medicine, Jilin University, Changchun, People's Republic of China.
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Two-component system YvqEC-dependent bacterial resistance against vancomycin in Bacillus thuringiensis. Antonie van Leeuwenhoek 2015; 108:365-76. [PMID: 26025304 DOI: 10.1007/s10482-015-0489-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 05/19/2015] [Indexed: 02/06/2023]
Abstract
YvqEC is one of the two-component signal transduction systems that may respond to cell envelope stress and enable cells to adjust multiple cellular functions. It consists of a histidine kinase YvqE and a response regulator YvqC. In this study, we separately constructed a single gene mutant ΔyvqE and a double gene mutant ΔyvqEC in Bacillus thuringiensis BMB171 through a homing endonucleases I-SceI mediated markerless gene deletion method. We found that the deletion of either yvqE or yvqEC weakened the resistance of B. thuringiensis against vancomycin. We also identified nine operons that may be involved in the cellular metabolism regulated by YvqC. This study not only enriches our understanding of bacterial resistance mechanisms against vancomycin, but also helps investigate the functions of YvqEC.
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Shankar M, Mohapatra SS, Biswas S, Biswas I. Gene Regulation by the LiaSR Two-Component System in Streptococcus mutans. PLoS One 2015; 10:e0128083. [PMID: 26020679 PMCID: PMC4447274 DOI: 10.1371/journal.pone.0128083] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 04/23/2015] [Indexed: 12/22/2022] Open
Abstract
The LiaSR two-component signal transduction system regulates cellular responses to several environmental stresses, including those that induce cell envelope damages. Downstream regulons of the LiaSR system have been implicated in tolerance to acid, antibiotics and detergents. In the dental pathogen Streptococcus mutans, the LiaSR system is necessary for tolerance against acid, antibiotics, and cell wall damaging stresses during growth in the oral cavity. To understand the molecular mechanisms by which LiaSR regulates gene expression, we created a mutant LiaR in which the conserved aspartic acid residue (the phosphorylation site), was changed to alanine residue (D58A). As expected, the LiaR-D58A variant was unable to acquire the phosphate group and bind to target promoters. We also noted that the predicted LiaR-binding motif upstream of the lia operon does not appear to be well conserved. Consistent with this observation, we found that LiaR was unable to bind to the promoter region of lia; however, we showed that LiaR was able to bind to the promoters of SMU.753, SMU.2084 and SMU.1727. Based on sequence analysis and DNA binding studies we proposed a new 25-bp conserved motif essential for LiaR binding. Introducing alterations at fully conserved positions in the 25-bp motif affected LiaR binding, and the binding was dependent on the combination of positions that were altered. By scanning the S. mutans genome for the occurrence of the newly defined LiaR binding motif, we identified the promoter of hrcA (encoding a key regulator of the heat shock response) that contains a LiaR binding motif, and we showed that hrcA is negatively regulated by the LiaSR system. Taken together our results suggest a putative role of the LiaSR system in heat shock responses of S. mutans.
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Affiliation(s)
- Manoharan Shankar
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Saswat S. Mohapatra
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Saswati Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
- * E-mail:
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29
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Min L, Jiawei Y, Yaling L, Yuqing H. [Effects of growth stages and pH value on the expression of autolytic enzyme atIS gene of Streptococcus gordonii]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2015; 33:80-83. [PMID: 25872305 PMCID: PMC7030257 DOI: 10.7518/hxkq.2015.01.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 09/21/2014] [Indexed: 06/04/2023]
Abstract
OBJECTIVE This study aimed to detect the difference in the expression levels of autolysin atIS gene of Streptococcus gordonii (S. gordonii) at different growth stages and pH values, as well as to analyze the factors regulating atlS gene expression in S. gordonii. METHODS S. gordonii wild strains (ATCC 35105) were collected at different growth stages (early exponential phase, mid-exponential phase, late exponential stage, and platform stage) and pH values (pH 7 and pH 5.5), and total RNA was extracted by using a conventional method. Fluorescence quantitative polymerase chain reaction (FQ-PCR) was used to measure the relative mRNA expression of atlS gene, with bacterial 16S rRNA as internal reference, for a comparison of the mRNA levels of atlS gene expression in S.gordonii at different growth stages and pH values. RESULTS FQ-PCR results showed that atlS gene expression increased with gradually increasing growth stage under neutral conditions and was higher than that under acidic conditions (P < 0.05). CONCLUSION The atlS gene expression in S. gordonii is influenced by growth stage and pH value factors.
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30
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Reyes J, Panesso D, Tran TT, Mishra NN, Cruz MR, Munita JM, Singh KV, Yeaman MR, Murray BE, Shamoo Y, Garsin D, Bayer AS, Arias CA. A liaR deletion restores susceptibility to daptomycin and antimicrobial peptides in multidrug-resistant Enterococcus faecalis. J Infect Dis 2014; 211:1317-25. [PMID: 25362197 DOI: 10.1093/infdis/jiu602] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Daptomycin is a lipopeptide antibiotic that is used clinically against many gram-positive bacterial pathogens and is considered a key frontline bactericidal antibiotic to treat multidrug-resistant enterococci. Emergence of daptomycin resistance during therapy of serious enterococcal infections is a major clinical issue. In this work, we show that deletion of the gene encoding the response regulator, LiaR (a member of the LiaFSR system that controls cell envelope homeostasis), from daptomycin-resistant Enterococcus faecalis not only reversed resistance to 2 clinically available cell membrane-targeting antimicrobials (daptomycin and telavancin), but also resulted in hypersusceptibility to these antibiotics and to a variety of antimicrobial peptides of diverse origin and with different mechanisms of action. The changes in susceptibility to these antibiotics and antimicrobial peptides correlated with in vivo attenuation in a Caenorhabditis elegans model. Mechanistically, deletion of liaR altered the localization of cardiolipin microdomains in the cell membrane. Our findings suggest that LiaR is a master regulator of the enterococcal cell membrane response to diverse antimicrobial agents and peptides; as such, LiaR represents a novel target to restore the activity of clinically useful antimicrobials against these organisms and, potentially, increase susceptibility to endogenous antimicrobial peptides.
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Affiliation(s)
- Jinnethe Reyes
- Division of Infectious Diseases, Department of Internal Medicine Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
| | - Diana Panesso
- Division of Infectious Diseases, Department of Internal Medicine Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
| | - Truc T Tran
- Division of Infectious Diseases, Department of Internal Medicine University of Houston College of Pharmacy
| | - Nagendra N Mishra
- Los Angeles Biomedical Research Institute, Harbor-University of California at Los Angeles Medical Center, Torrance David Geffen School of Medicine, University of California at Los Angeles
| | - Melissa R Cruz
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston
| | - Jose M Munita
- Division of Infectious Diseases, Department of Internal Medicine Clinica Alemana de Santiago and Universidad del Desarrollo, Chile
| | - Kavindra V Singh
- Division of Infectious Diseases, Department of Internal Medicine
| | - Michael R Yeaman
- Los Angeles Biomedical Research Institute, Harbor-University of California at Los Angeles Medical Center, Torrance David Geffen School of Medicine, University of California at Los Angeles
| | - Barbara E Murray
- Division of Infectious Diseases, Department of Internal Medicine Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston
| | - Yousif Shamoo
- Department of Biochemistry and Cell Biology Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas
| | - Danielle Garsin
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston
| | - Arnold S Bayer
- Los Angeles Biomedical Research Institute, Harbor-University of California at Los Angeles Medical Center, Torrance David Geffen School of Medicine, University of California at Los Angeles
| | - Cesar A Arias
- Division of Infectious Diseases, Department of Internal Medicine Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston Molecular Genetics and Antimicrobial Resistance Unit, Universidad El Bosque, Bogota, Colombia
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31
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Kingston AW, Liao X, Helmann JD. Contributions of the σ(W) , σ(M) and σ(X) regulons to the lantibiotic resistome of Bacillus subtilis. Mol Microbiol 2013; 90:502-18. [PMID: 23980836 PMCID: PMC4067139 DOI: 10.1111/mmi.12380] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2013] [Indexed: 11/28/2022]
Abstract
In Bacillus subtilis, the extracytoplasmic function (ECF) σ factors σ(M) , σ(W) and σ(X) all contribute to resistance against lantibiotics. Nisin, a model lantibiotic, has a dual mode of action: it inhibits cell wall synthesis by binding lipid II, and this complex also forms pores in the cytoplasmic membrane. These activities can be separated in a nisin hinge-region variant (N20P M21P) that binds lipid II, but no longer permeabilizes membranes. The major contribution of σ(M) to nisin resistance is expression of ltaSa, encoding a stress-activated lipoteichoic acid synthase, and σ(X) functions primarily by activation of the dlt operon controlling d-alanylation of teichoic acids. Together, σ(M) and σ(X) regulate cell envelope structure to decrease access of nisin to its lipid II target. In contrast, σ(W) is principally involved in protection against membrane permeabilization as it provides little protection against the nisin hinge region variant. σ(W) contributes to nisin resistance by regulation of a signal peptide peptidase (SppA), phage shock proteins (PspA and YvlC, a PspC homologue) and tellurite resistance related proteins (YceGHI). These defensive mechanisms are also effective against other lantibiotics such as mersacidin, gallidermin and subtilin and comprise an important subset of the intrinsic antibiotic resistome of B. subtilis.
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Affiliation(s)
| | - Xiaojie Liao
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
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Barendt S, Lee H, Birch C, Nakano MM, Jones M, Zuber P. Transcriptomic and phenotypic analysis of paralogous spx gene function in Bacillus anthracis Sterne. Microbiologyopen 2013; 2:695-714. [PMID: 23873705 PMCID: PMC3831629 DOI: 10.1002/mbo3.109] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 06/05/2013] [Accepted: 06/17/2013] [Indexed: 11/15/2022] Open
Abstract
Spx of Bacillus subtilis is a redox-sensitive protein, which, under disulfide stress, interacts with RNA polymerase to activate genes required for maintaining thiol homeostasis. Spx orthologs are highly conserved among low %GC Gram-positive bacteria, and often exist in multiple paralogous forms. In this study, we used B. anthracis Sterne, which harbors two paralogous spx genes, spxA1 and spxA2, to examine the phenotypes of spx null mutations and to identify the genes regulated by each Spx paralog. Cells devoid of spxA1 were sensitive to diamide and hydrogen peroxide, while the spxA1 spoxA2 double mutant was hypersensitive to the thiol-specific oxidant, diamide. Bacillus anthracis Sterne strains expressing spxA1DD or spxA2DD alleles encoding protease-resistant products were used in microarray and quantitative real-time polymerase chain reaction (RT-qPCR) analyses in order to uncover genes under SpxA1, SpxA2, or SpxA1/SpxA2 control. Comparison of transcriptomes identified many genes that were upregulated when either SpxA1DD or SpxA2DD was produced, but several genes were uncovered whose transcript levels increased in only one of the two SpxADD-expression strains, suggesting that each Spx paralog governs a unique regulon. Among genes that were upregulated were those encoding orthologs of proteins that are specifically involved in maintaining intracellular thiol homeostasis or alleviating oxidative stress. Some of these genes have important roles in B. anthracis pathogenesis, and a large number of upregulated hypothetical genes have no homology outside of the B. cereus/thuringiensis group. Microarray and RT-qPCR analyses also unveiled a regulatory link that exists between the two spx paralogous genes. The data indicate that spxA1 and spxA2 are transcriptional regulators involved in relieving disulfide stress but also control a set of genes whose products function in other cellular processes. Bacillus anthracis harbors two paralogs of the global transcriptional regulator of stress response, SpxA. SpxA1 and SpxA2 contribute to disulfide stress tolerance, but only SpxA1 functions in resistance to peroxide. Transcriptome analysis uncovered potential SpxA1 and SpxA2 regulon members, which include genes activated by both paralogs. However, paralog-specific gene activation was also observed. Genes encoding glutamate racemase, CoA disulfide reductase, and products functioning in bacillithiol biosynthesis, are among the genes activated by the SpxA paralogs.
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Affiliation(s)
- Skye Barendt
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health and Science University, Beaverton, Oregon
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33
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Klinzing DC, Ishmael N, Hotopp JCD, Tettelin H, Shields KR, Madoff LC, Puopolo KM. The two-component response regulator LiaR regulates cell wall stress responses, pili expression and virulence in group B Streptococcus. MICROBIOLOGY-SGM 2013; 159:1521-1534. [PMID: 23704792 DOI: 10.1099/mic.0.064444-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Group B Streptococcus (GBS) remains the leading cause of early onset sepsis among term infants. Evasion of innate immune defences is critical to neonatal GBS disease pathogenesis. Effectors of innate immunity, as well as numerous antibiotics, frequently target the peptidoglycan layer of the Gram-positive bacterial cell wall. The intramembrane-sensing histidine kinase (IM-HK) class of two-component regulatory systems has been identified as important to the Gram-positive response to cell wall stress. We have characterized the GBS homologue of LiaR, the response regulator component of the Lia system, to determine its role in GBS pathogenesis. LiaR is expressed as part of a three-gene operon (liaFSR) with a promoter located upstream of liaF. A LiaR deletion mutant is more susceptible to cell wall-active antibiotics (vancomycin and bacitracin) as well as antimicrobial peptides (polymixin B, colistin, and nisin) compared to isogenic wild-type GBS. LiaR mutant GBS are significantly attenuated in mouse models of both GBS sepsis and pneumonia. Transcriptional profiling with DNA microarray and Northern blot demonstrated that LiaR regulates expression of genes involved in microbial defence against host antimicrobial systems including genes functioning in cell wall synthesis, pili formation and cell membrane modification. We conclude that the LiaFSR system, the first member of the IM-HK regulatory systems to be studied in GBS, is involved in sensing perturbations in the integrity of the cell wall and activates a transcriptional response that is important to the pathogenesis of GBS infection.
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Affiliation(s)
- David C Klinzing
- Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA.,Channing Laboratory, Brigham and Women's Hospital, 181 Longwood Avenue, Boston, MA 02115, USA
| | - Nadeeza Ishmael
- Institute for Genome Sciences, University of Maryland Baltimore, 801 West Baltimore Street, Baltimore, MD 21201, USA.,The J. Craig Venter Institute, 9712 Medical Center Drive, Rockville, MD 20850, USA
| | - Julie C Dunning Hotopp
- Institute for Genome Sciences, University of Maryland Baltimore, 801 West Baltimore Street, Baltimore, MD 21201, USA.,The J. Craig Venter Institute, 9712 Medical Center Drive, Rockville, MD 20850, USA
| | - Hervé Tettelin
- Institute for Genome Sciences, University of Maryland Baltimore, 801 West Baltimore Street, Baltimore, MD 21201, USA.,The J. Craig Venter Institute, 9712 Medical Center Drive, Rockville, MD 20850, USA
| | - Kelly R Shields
- Channing Laboratory, Brigham and Women's Hospital, 181 Longwood Avenue, Boston, MA 02115, USA
| | - Lawrence C Madoff
- Massachusetts Department of Public Health, Jamaica Plain, MA 02130, USA.,Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, 55 Lake Avenue, North Worcester, MA 01655, USA
| | - Karen M Puopolo
- Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA.,Department of Newborn Medicine, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.,Channing Laboratory, Brigham and Women's Hospital, 181 Longwood Avenue, Boston, MA 02115, USA
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34
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A liaF codon deletion abolishes daptomycin bactericidal activity against vancomycin-resistant Enterococcus faecalis. Antimicrob Agents Chemother 2013; 57:2831-3. [PMID: 23507277 DOI: 10.1128/aac.00021-13] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The genetic bases for antibiotic tolerance are obscure. Daptomycin (DAP) is a lipopeptide antibiotic with bactericidal activity against enterococci. Using time-kill assays, we provide evidence for the first time that a deletion of isoleucine in position 177 of LiaF, a member of the three-component regulatory system LiaFSR involved in the cell envelope response to antimicrobials, is directly responsible for a DAP-tolerant phenotype and is likely to negatively affect response to DAP therapy.
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35
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Whole-genome analysis of a daptomycin-susceptible enterococcus faecium strain and its daptomycin-resistant variant arising during therapy. Antimicrob Agents Chemother 2012; 57:261-8. [PMID: 23114757 DOI: 10.1128/aac.01454-12] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Development of daptomycin (DAP) resistance in Enterococcus faecalis has recently been associated with mutations in genes encoding proteins with two main functions: (i) control of the cell envelope stress response to antibiotics and antimicrobial peptides (LiaFSR system) and (ii) cell membrane phospholipid metabolism (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase [cls]). However, the genetic bases for DAP resistance in Enterococcus faecium are unclear. We performed whole-genome comparative analysis of a clinical strain pair, DAP-susceptible E. faecium S447 and its DAP-resistant derivative R446, which was recovered from a single patient during DAP therapy. By comparative whole-genome sequencing, DAP resistance in R446 was associated with changes in 8 genes. Two of these genes encoded proteins involved in phospholipid metabolism: (i) an R218Q substitution in Cls and (ii) an A292G reversion in a putative cyclopropane fatty acid synthase enzyme. The DAP-resistant derivative R446 also exhibited an S333L substitution in the putative histidine kinase YycG, a member of the YycFG system, which, similar to LiaFSR, has been involved in cell envelope homeostasis and DAP resistance in other Gram-positive cocci. Additional changes identified in E. faecium R446 (DAP resistant) included two putative proteins involved in transport (one for carbohydrate and one for sulfate) and three enzymes predicted to play a role in general metabolism. Exchange of the "susceptible" cls allele from S447 for the "resistant" one belonging to R446 did not affect DAP susceptibility. Our results suggest that, apart from the LiaFSR system, the essential YycFG system is likely to be an important mediator of DAP resistance in some E. faecium strains.
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36
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Correlation between mutations in liaFSR of Enterococcus faecium and MIC of daptomycin: revisiting daptomycin breakpoints. Antimicrob Agents Chemother 2012; 56:4354-9. [PMID: 22664970 DOI: 10.1128/aac.00509-12] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Mutations in liaFSR, a three-component regulatory system controlling cell-envelope stress response, were recently linked with the emergence of daptomycin (DAP) resistance in enterococci. Our previous work showed that a liaF mutation increased the DAP MIC of a vancomycin-resistant Enterococcus faecalis strain from 1 to 3 μg/ml (the DAP breakpoint is 4 μg/ml), suggesting that mutations in the liaFSR system could be a pivotal initial event in the development of DAP resistance. With the hypothesis that clinical enterococcal isolates with DAP MICs between 3 and 4 μg/ml might harbor mutations in liaFSR, we studied 38 Enterococcus faecium bloodstream isolates, of which 8 had DAP MICs between 3 and 4 μg/ml by Etest in Mueller-Hinton agar. Interestingly, 6 of these 8 isolates had predicted amino acid changes in the LiaFSR system. Moreover, we previously showed that among 6 DAP-resistant E. faecium isolates (MICs of >4 μg/ml), 5 had mutations in liaFSR. In contrast, none of 16 E. faecium isolates with a DAP MIC of ≤2 μg/ml harbored mutations in this system (P < 0.0001). All but one isolate with liaFSR changes exhibited DAP MICs of ≥16 μg/ml by Etest using brain heart infusion agar (BHIA), a medium that better supports enterococcal growth. Our findings provide a strong association between DAP MICs within the upper susceptibility range and mutations in the liaFSR system. Concomitant susceptibility testing on BHIA may be useful for identifying these E. faecium first-step mutants. Our results also suggest that the current DAP breakpoint for E. faecium may need to be reevaluated.
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37
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CpsY influences Streptococcus iniae cell wall adaptations important for neutrophil intracellular survival. Infect Immun 2012; 80:1707-15. [PMID: 22354020 DOI: 10.1128/iai.00027-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The ability of a pathogen to evade neutrophil phagocytic killing mechanisms is critically important for dissemination and establishment of a systemic infection. Understanding how pathogens overcome these innate defenses is essential for the development of optimal therapeutic strategies for invasive infections. CpsY is a conserved transcriptional regulator previously identified as an important virulence determinant for systemic infection of Streptococcus iniae. While orthologs of CpsY have been associated with the regulation of methionine metabolism and uptake pathways, CpsY additionally functions in protection from neutrophil-mediated killing. S. iniae does not alter neutrophil phagosomal maturation but instead is able to adapt to the extreme bactericidal environment of a mature neutrophil phagosome, a property dependent upon CpsY. This CpsY-dependent adaptation appears to involve stabilization of the cell wall through peptidoglycan O-acetylation and repression of cellular autolysins. Furthermore, S. iniae continues to be a powerful model for investigation of bacterial adaptations during systemic streptococcal infection.
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Listeria monocytogenes shows temperature-dependent and -independent responses to salt stress, including responses that induce cross-protection against other stresses. Appl Environ Microbiol 2012; 78:2602-12. [PMID: 22307309 DOI: 10.1128/aem.07658-11] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The food-borne pathogen Listeria monocytogenes experiences osmotic stress in many habitats, including foods and the gastrointestinal tract of the host. During transmission, L. monocytogenes is likely to experience osmotic stress at different temperatures and may adapt to osmotic stress in a temperature-dependent manner. To understand the impact of temperature on the responses this pathogen uses to adapt to osmotic stress, we assessed genome-wide changes in the L. monocytogenes H7858 transcriptome during short-term and long-term adaptation to salt stress at 7°C and 37°C. At both temperatures, the short-term response to salt stress included increased transcript levels of sigB and SigB-regulated genes, as well as mrpABCDEFG, encoding a sodium/proton antiporter. This antiporter was found to play a role in adaptation to salt stress at both temperatures; ΔmrpABCDEFG had a significantly longer lag phase than the parent strain in BHI plus 6% NaCl at 7°C and 37°C. The short-term adaptation to salt stress at 7°C included increased transcript levels of two genes encoding carboxypeptidases that modify peptidoglycan. These carboxypeptidases play a role in the short-term adaptation to salt stress only at 7°C, where the deletion mutants had significantly different lag phases than the parent strain. Changes in the transcriptome at both temperatures suggested that exposure to salt stress could provide cross-protection to other stresses, including peroxide stress. Short-term exposure to salt stress significantly increased H(2)O(2) resistance at both temperatures. These results provide information for the development of knowledge-based intervention methods against this pathogen, as well as provide insight into potential mechanisms of cross-protection.
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Moscoso M, Domenech M, García E. Vancomycin tolerance in Gram-positive cocci. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:640-650. [PMID: 23761352 DOI: 10.1111/j.1758-2229.2011.00254.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Vancomycin, a glycopeptide antimicrobial agent, represents the last line of defence against a wide range of multi-resistant Gram-positive pathogens such as enterococci, staphylococci and streptococci. However, vancomycin-resistant enterococci and staphylococci, along with vancomycin-tolerant clinical isolates, are compromising the therapeutic efficacy of vancomycin. It is conceivable that tolerance may emerge during prolonged vancomycin use. It has not been until recently, however, that the molecular basis of this tolerance began to be understood. Superoxide anions might be involved in the bactericidal activity of vancomycin in enterococci, and recent evidence suggests that the stringent response is partly responsible for vancomycin tolerance in Enterococcus faecalis. The mechanism of vancomycin tolerance in Staphylococcus aureus and Streptococcus pneumoniae is sometimes associated with a reduction of autolysin activity. Vancomycin tolerance in S. aureus and S. pneumoniae also appears to be somehow related with the two-component regulatory systems linked to cell envelope stress, although the precise molecular regulatory pathways remain poorly defined.
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Affiliation(s)
- Miriam Moscoso
- Departamento de Microbiología Molecular y Biología de las Infecciones, Centro de Investigaciones Biológicas (CSIC) and CIBER de Enfermedades Respiratorias (CIBERES), Ramiro de Maeztu, 9, 28040 Madrid, Spain
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Arias CA, Panesso D, McGrath DM, Qin X, Mojica MF, Miller C, Diaz L, Tran TT, Rincon S, Barbu EM, Reyes J, Roh JH, Lobos E, Sodergren E, Pasqualini R, Arap W, Quinn JP, Shamoo Y, Murray BE, Weinstock GM. Genetic basis for in vivo daptomycin resistance in enterococci. N Engl J Med 2011; 365:892-900. [PMID: 21899450 PMCID: PMC3205971 DOI: 10.1056/nejmoa1011138] [Citation(s) in RCA: 254] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Daptomycin is a lipopeptide with bactericidal activity that acts on the cell membrane of enterococci and is often used off-label to treat patients infected with vancomycin-resistant enterococci. However, the emergence of resistance to daptomycin during therapy threatens its usefulness. METHODS We performed whole-genome sequencing and characterization of the cell envelope of a clinical pair of vancomycin-resistant Enterococcus faecalis isolates from the blood of a patient with fatal bacteremia; one isolate (S613) was from blood drawn before treatment and the other isolate (R712) was from blood drawn after treatment with daptomycin. The minimal inhibitory concentrations (MICs) of these two isolates were 1 and 12 μg per milliliter, respectively. Gene replacements were made to exchange the alleles found in isolate S613 with those in isolate R712. RESULTS Isolate R712 had in-frame deletions in three genes. Two genes encoded putative enzymes involved in phospholipid metabolism, GdpD (which denotes glycerophosphoryl diester phosphodiesterase) and Cls (which denotes cardiolipin synthetase), and one gene encoded a putative membrane protein, LiaF (which denotes lipid II cycle-interfering antibiotics protein but whose exact function is not known). LiaF is predicted to be a member of a three-component regulatory system (LiaFSR) involved in the stress-sensing response of the cell envelope to antibiotics. Replacement of the liaF allele of isolate S613 with the liaF allele from isolate R712 quadrupled the MIC of daptomycin, whereas replacement of the gdpD allele had no effect on MIC. Replacement of both the liaF and gdpD alleles of isolate S613 with the liaF and gdpD alleles of isolate R712 raised the daptomycin MIC for isolate S613 to 12 μg per milliliter. As compared with isolate S613, isolate R712--the daptomycin-resistant isolate--had changes in the structure of the cell envelope and alterations in membrane permeability and membrane potential. CONCLUSIONS Mutations in genes encoding LiaF and a GdpD-family protein were necessary and sufficient for the development of resistance to daptomycin during the treatment of vancomycin-resistant enterococci. (Funded by the National Institute of Allergy and Infectious Diseases and the National Institutes of Health.).
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Affiliation(s)
- Cesar A Arias
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Medical School at Houston, Houston, TX 77030, USA.
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Mutational analyses of open reading frames within the vraSR operon and their roles in the cell wall stress response of Staphylococcus aureus. Antimicrob Agents Chemother 2011; 55:1391-402. [PMID: 21220524 DOI: 10.1128/aac.01213-10] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The exposure of Staphylococcus aureus to a broad range of cell wall-damaging agents triggers the induction of a cell wall stress stimulon (CWSS) controlled by the VraSR two-component system. The vraSR genes form part of the four-cistron autoregulatory operon orf1-yvqF-vraS-vraR. The markerless inactivation of each of the genes within this operon revealed that orf1 played no observable role in CWSS induction and had no influence on resistance phenotypes for any of the cell envelope stress-inducing agents tested. The remaining three genes were all essential for the induction of the CWSS, and mutants showed various degrees of increased susceptibility to cell wall-active antibiotics. Therefore, the role of YvqF in S. aureus appears to be opposite that in other Gram-positive bacteria, where YvqF homologs have all been shown to inhibit signal transduction. This role, as an activator rather than repressor of signal transduction, corresponds well with resistance phenotypes of ΔYvqF mutants, which were similar to those of ΔVraR mutants in which CWSS induction also was completely abolished. Resistance profiles of ΔVraS mutants differed phenotypically from those of ΔYvqF and ΔVraR mutants on many non-ß-lactam antibiotics. ΔVraS mutants still became more susceptible than wild-type strains at low antibiotic concentrations, but they retained larger subpopulations that were able to grow on higher antibiotic concentrations than ΔYvqF and ΔVraR mutants. Subpopulations of ΔVraS mutants could grow on even higher glycopeptide concentrations than wild-type strains. The expression of a highly sensitive CWSS-luciferase reporter gene fusion was up to 2.6-fold higher in a ΔVraS than a ΔVraR mutant, which could be linked to differences in their respective antibiotic resistance phenotypes. Bacterial two-hybrid analysis indicated that the integral membrane protein YvqF interacted directly with VraS but not VraR, suggesting that it plays an essential role in sensing the as-yet unknown trigger of CWSS induction.
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Fritsch F, Mauder N, Williams T, Weiser J, Oberle M, Beier D. The cell envelope stress response mediated by the LiaFSRLm three-component system of Listeria monocytogenes is controlled via the phosphatase activity of the bifunctional histidine kinase LiaSLm. MICROBIOLOGY-SGM 2010; 157:373-386. [PMID: 21030435 DOI: 10.1099/mic.0.044776-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Most members of the phylum Firmicutes harbour a two-component system (TCS), LiaSR, which is involved in the response to cell envelope stress elicited most notably by inhibitors of the lipid II cycle. In all LiaSR systems studied in detail, LiaSR-mediated signal transduction has been shown to be negatively controlled by a membrane protein, LiaF, encoded upstream of liaSR. In this study we have analysed the LiaSR orthologue of Listeria monocytogenes (LiaSR(Lm)). Whole-genome transcriptional profiling indicated that activation of LiaSR(Lm) results in a remodelling of the cell envelope via the massive upregulation of membrane-associated and extracytoplasmic proteins in the presence of inducing stimuli. As shown for other LiaSR TCSs, LiaSR(Lm) is activated by cell wall-active antibiotics. We demonstrate that the level of phosphorylated LiaR(Lm), which is required for the induction of the LiaSR(Lm) regulon, is controlled by the interplay between the histidine kinase and phosphatase activities of the bifunctional sensor protein LiaS(Lm). Our data suggest that the phosphatase activity of LiaS(Lm) is stimulated by LiaF(Lm) in the absence of cell envelope stress.
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Affiliation(s)
- Frederike Fritsch
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Norman Mauder
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Tatjana Williams
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Julia Weiser
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Markus Oberle
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Dagmar Beier
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Abstract
The Lia system, a cell envelope stress response module of Bacillus subtilis, is comprised of the LiaRS two-component system and a membrane-anchored inhibitor protein, LiaF. It is highly conserved in the Firmicutes bacteria, and all orthologs investigated so far are activated by cell wall antibiotics. In response to envelope stress, the systems in Firmicutes cocci induce the expression of a number of genes that are involved in conferring resistance against its inducers. In contrast, a complete picture of the LiaR regulon of B. subtilis is still missing and no phenotypes could be associated with mutants lacking LiaRS. Here, we performed genome-wide transcriptomic, proteomic, and in-depth phenotypic profiling of constitutive "Lia ON" and "Lia OFF" mutants to obtain a comprehensive picture of the Lia response of Bacillus subtilis. In addition to the known targets liaIH and yhcYZ-yhdA, we identified ydhE as a novel gene affected by LiaR-dependent regulation. The results of detailed follow-up gene expression studies, together with proteomic analysis, demonstrate that the liaIH operon represents the only relevant LiaR target locus in vivo. It encodes a small membrane protein (LiaI) and a phage shock protein homolog (LiaH). LiaH forms large oligomeric rings reminiscent of those described for Escherichia coli PspA or Arabidopsis thaliana Vipp1. The results of comprehensive phenotype studies demonstrated that the gene products of the liaIH operon are involved in protecting the cell against oxidative stress and some cell wall antibiotics. Our data suggest that the LiaFSR system of B. subtilis and, presumably, other Firmicutes bacilli coordinates a phage shock protein-like response.
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