1
|
Jian Y, Chen T, Yang Z, Xiang G, Xu K, Wang Y, Zhao N, He L, Liu Q, Li M. Small regulatory RNA RSaX28 promotes virulence by reinforcing the stability of RNAIII in community-associated ST398 clonotype Staphylococcus aureus. Emerg Microbes Infect 2024; 13:2341972. [PMID: 38597192 PMCID: PMC11034457 DOI: 10.1080/22221751.2024.2341972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 04/06/2024] [Indexed: 04/11/2024]
Abstract
Staphylococcus aureus (S. aureus) is a notorious pathogen that cause metastatic or complicated infections. Hypervirulent ST398 clonotype strains, remarkably increased in recent years, dominated Community-associated S. aureus (CA-SA) infections in the past decade in China. Small RNAs like RNAIII have been demonstrated to play important roles in regulating the virulence of S. aureus, however, the regulatory roles played by many of these sRNAs in the ST398 clonotype strains are still unclear. Through transcriptome screening and combined with knockout phenotype analysis, we have identified a highly transcribed sRNA, RSaX28, in the ST398 clonotype strains. Sequence analysis revealed that RSaX28 is highly conserved in the most epidemic clonotypes of S. aureus, but its high transcription level is particularly prominent in the ST398 clonotype strains. Characterization of RSaX28 through RACE and Northern blot revealed its length to be 533nt. RSaX28 is capable of promoting the hemolytic ability, reducing biofilm formation capacity, and enhancing virulence of S. aureus in the in vivo murine infection model. Through IntaRNA prediction and EMSA validation, we found that RSaX28 can specifically interact with RNAIII, promoting its stability and positively regulating the translation of downstream alpha-toxin while inhibiting the translation of Sbi, thereby regulating the virulence and biofilm formation capacity of the ST398 clonotype strains. RSaX28 is an important virulence regulatory factor in the ST398 clonotype S. aureus and represents a potential important target for future treatment and immune intervention against S. aureus infections.
Collapse
Affiliation(s)
- Ying Jian
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Tianchi Chen
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Ziyu Yang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Guoxiu Xiang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Kai Xu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Yanan Wang
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Na Zhao
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Lei He
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Qian Liu
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Min Li
- Department of Laboratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
- Faculty of Medical Laboratory Science, College of Health Science and Technology, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| |
Collapse
|
2
|
Kato F, Bandou R, Yamaguchi Y, Inouye K, Inouye M. Characterization of a membrane toxin-antitoxin system, tsaAT, from Staphylococcus aureus. FEBS J 2024. [PMID: 39356479 DOI: 10.1111/febs.17289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 08/01/2024] [Accepted: 09/23/2024] [Indexed: 10/03/2024]
Abstract
Bacterial toxin-antitoxin (TA) systems consist of a toxin that inhibits essential cellular processes, such as DNA replication, transcription, translation, or ATP synthesis, and an antitoxin neutralizing their cognate toxin. These systems have roles in programmed cell death, defense against phage, and the formation of persister cells. Here, we characterized the previously identified Staphylococcus aureus TA system, tsaAT, which consists of two putative membrane proteins: TsaT and TsaA. Expression of the TsaT toxin caused cell death and disrupted membrane integrity, whereas TsaA did not show any toxicity and neutralized the toxicity of TsaT. Furthermore, subcellular fractionation analysis demonstrated that both TsaA and TsaT localized to the cytoplasmic membrane of S. aureus expressing either or both 3xFLAG-tagged TsaA and 3xFLAG-tagged TsaT. Taken together, these results demonstrate that the TsaAT TA system consists of two membrane proteins, TsaA and TsaT, where TsaT disrupts membrane integrity, ultimately leading to cell death. Although sequence analyses showed that the tsaA and tsaT genes were conserved among Staphylococcus species, amino acid substitutions between TsaT orthologs highlighted the critical role of the 6th residue for its toxicity. Further amino acid substitutions indicated that the glutamic acid residue at position 63 in the TsaA antitoxin and the cluster of five lysine residues in the TsaT toxin are involved in TsaA's neutralization reaction. This study is the first to describe a bacterial TA system wherein both toxin and antitoxin are membrane proteins. These findings contribute to our understanding of S. aureus TA systems and, more generally, give new insight into highly diverse bacterial TA systems.
Collapse
Affiliation(s)
- Fuminori Kato
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Risa Bandou
- Faculty of Dentistry, Hiroshima University, Japan
| | - Yoshihiro Yamaguchi
- Department of Biology, Graduate School of Sciences, Osaka Metropolitan University, Japan
| | - Keiko Inouye
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Masayori Inouye
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| |
Collapse
|
3
|
Saunier M, Fortier LC, Soutourina O. RNA-based regulation in bacteria-phage interactions. Anaerobe 2024; 87:102851. [PMID: 38583547 DOI: 10.1016/j.anaerobe.2024.102851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 03/24/2024] [Accepted: 04/02/2024] [Indexed: 04/09/2024]
Abstract
Interactions of bacteria with their viruses named bacteriophages or phages shape the bacterial genome evolution and contribute to the diversity of phages. RNAs have emerged as key components of several anti-phage defense systems in bacteria including CRISPR-Cas, toxin-antitoxin and abortive infection. Frequent association with mobile genetic elements and interplay between different anti-phage defense systems are largely discussed. Newly discovered defense systems such as retrons and CBASS include RNA components. RNAs also perform their well-recognized regulatory roles in crossroad of phage-bacteria regulatory networks. Both regulatory and defensive function can be sometimes attributed to the same RNA molecules including CRISPR RNAs. This review presents the recent advances on the role of RNAs in the bacteria-phage interactions with a particular focus on clostridial species including an important human pathogen, Clostridioides difficile.
Collapse
Affiliation(s)
- Marion Saunier
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France; Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Louis-Charles Fortier
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Olga Soutourina
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France; Institut Universitaire de France (IUF), Paris, France.
| |
Collapse
|
4
|
Brantl S, Ul Haq I. Small proteins in Gram-positive bacteria. FEMS Microbiol Rev 2023; 47:fuad064. [PMID: 38052429 PMCID: PMC10730256 DOI: 10.1093/femsre/fuad064] [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: 10/25/2023] [Revised: 11/27/2023] [Accepted: 12/04/2023] [Indexed: 12/07/2023] Open
Abstract
Small proteins comprising less than 100 amino acids have been often ignored in bacterial genome annotations. About 10 years ago, focused efforts started to investigate whole peptidomes, which resulted in the discovery of a multitude of small proteins, but only a number of them have been characterized in detail. Generally, small proteins can be either membrane or cytosolic proteins. The latter interact with larger proteins, RNA or even metal ions. Here, we summarize our current knowledge on small proteins from Gram-positive bacteria with a special emphasis on the model organism Bacillus subtilis. Our examples include membrane-bound toxins of type I toxin-antitoxin systems, proteins that block the assembly of higher order structures, regulate sporulation or modulate the RNA degradosome. We do not consider antimicrobial peptides. Furthermore, we present methods for the identification and investigation of small proteins.
Collapse
Affiliation(s)
- Sabine Brantl
- AG Bakteriengenetik, Matthias-Schleiden-Institut, Friedrich-Schiller-Universität Jena, Philosophenweg 12, Jena D-07743, Germany
| | - Inam Ul Haq
- AG Bakteriengenetik, Matthias-Schleiden-Institut, Friedrich-Schiller-Universität Jena, Philosophenweg 12, Jena D-07743, Germany
| |
Collapse
|
5
|
Fermon L, Burel A, Ostyn E, Dréano S, Bondon A, Chevance S, Pinel-Marie ML. Mechanism of action of sprG1-encoded type I toxins in Staphylococcus aureus: from membrane alterations to mesosome-like structures formation and bacterial lysis. Front Microbiol 2023; 14:1275849. [PMID: 37854335 PMCID: PMC10579593 DOI: 10.3389/fmicb.2023.1275849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 09/11/2023] [Indexed: 10/20/2023] Open
Abstract
sprG1/SprF1 is a type I toxin-antitoxin system located on Staphylococcus aureus prophage. It has previously been shown that the two toxins, SprG131 and SprG144, encoded by the sprG1 gene, are two membrane-associated peptides structured in a single α-helix. Overexpression of these two peptides leads to growth inhibition and even S. aureus death. In this study, we investigated the involvement of each peptide in this toxicity, the sequence requirements necessary for SprG131 toxicity, and the mechanism of action of these two peptides. Our findings show that both peptides, when expressed individually, are able to stop growth, with higher toxicity observed for SprG131. The combination of a hydrophobic domain and a charged domain located only at the C-terminus is necessary for this toxicity, likely to retain the orientation of the transmembrane domain. A net cationic charge for SprG131 is not essential to induce a growth defect in S. aureus. Furthermore, we established a chronology of toxic events following overexpression to gain insights into the mode of action of SprG144 and SprG131. We demonstrated that mesosome-like structures are already formed when membrane is depolarized, about 20 min after peptides induction. This membrane depolarization occurs concomitantly with a depletion of intracellular ATP, leading to S. aureus growth arrest. Moreover, we hypothesized that SprG144 and SprG131 do not form large pores in the S. aureus membrane, as ATP is not excreted into the extracellular medium, and membrane permeabilization is delayed relative to membrane depolarization. The next challenge is to identify the conditions under which SprG144 and SprG131 are naturally expressed, and to uncover their potential roles during staphylococcal growth, colonization, and infection.
Collapse
Affiliation(s)
- Laurence Fermon
- Univ Rennes, INSERM, BRM – UMR_S 1230, Rennes, France
- Univ Rennes, CNRS, ISCR – UMR 6226, Rennes, France
| | - Agnès Burel
- Univ Rennes, CNRS, INSERM, BIOSIT – UAR 3480, US_S 018, Rennes, France
| | - Emeline Ostyn
- Univ Rennes, INSERM, BRM – UMR_S 1230, Rennes, France
| | | | | | | | | |
Collapse
|
6
|
Kato F, Yamaguchi Y, Inouye K, Matsuo K, Ishida Y, Inouye M. A novel gyrase inhibitor from toxin-antitoxin system expressed by Staphylococcus aureus. FEBS J 2023; 290:1502-1518. [PMID: 36148483 DOI: 10.1111/febs.16634] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 09/12/2022] [Accepted: 09/22/2022] [Indexed: 11/30/2022]
Abstract
Toxin-antitoxin (TA) systems consist of a toxin inhibiting essential cellular functions (such as DNA, RNA and protein synthesis), and its cognate antitoxin neutralizing the toxicity. Recently, we identified a TA system termed TsbA/TsbT in the Staphylococcus aureus genome. The induction of the tsbT gene in Escherichia coli halted both DNA and RNA synthesis, reduced supercoiled plasmid and resulted in increasingly relaxed DNA. These results suggested that DNA gyrase was the target of TsbT. In addition, TsbT inhibited both E. coli and S. aureus DNA gyrase activity and induced linearization of plasmid DNA in vitro. Taken together, these results demonstrate that the TsbT toxin targets DNA gyrase in vivo. Site-directed mutagenesis experiments showed that the E27 and D37 residues in TsbT are critical for toxicity. Secondary structure prediction combining the analysis of vacuum-ultraviolet circular-dichroism spectroscopy and neural network method demonstrated that the 22nd-32nd residues of TsbT form an α-helix structure, and that the E27 residue is located around the centre of the α-helix segment. These findings give new insights not only into S. aureus TA systems, but also into bacterial toxins targeting DNA topoisomerases.
Collapse
Affiliation(s)
- Fuminori Kato
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Yoshihiro Yamaguchi
- Department of Biology and Geosciences, Graduate School of Sciences, Osaka City University, Japan
| | - Keiko Inouye
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Koichi Matsuo
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Japan
| | - Yojiro Ishida
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Masayori Inouye
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| |
Collapse
|
7
|
Menard G, Silard C, Suriray M, Rouillon A, Augagneur Y. Thirty Years of sRNA-Mediated Regulation in Staphylococcus aureus: From Initial Discoveries to In Vivo Biological Implications. Int J Mol Sci 2022; 23:ijms23137346. [PMID: 35806357 PMCID: PMC9266662 DOI: 10.3390/ijms23137346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/20/2022] [Accepted: 06/28/2022] [Indexed: 01/27/2023] Open
Abstract
Staphylococcus aureus is a widespread livestock and human pathogen that colonizes diverse microenvironments within its host. Its adaptation to the environmental conditions encountered within humans relies on coordinated gene expression. This requires a sophisticated regulatory network, among which regulatory RNAs (usually called sRNAs) have emerged as key players over the last 30 years. In S. aureus, sRNAs regulate target genes at the post-transcriptional level through base–pair interactions. The functional characterization of a subset revealed that they participate in all biological processes, including virulence, metabolic adaptation, and antibiotic resistance. In this review, we report 30 years of S. aureus sRNA studies, from their discovery to the in-depth characterizations of some of them. We also discuss their actual in vivo contribution, which is still lagging behind, and their place within the complex regulatory network. These shall be key aspects to consider in order to clearly uncover their in vivo biological functions.
Collapse
Affiliation(s)
- Guillaume Menard
- CHU Rennes, INSERM, BRM (Bacterial Regulatory RNAs and Medicine), SB2H (Service de Bactériologie Hygiène-Hospitalière), University Rennes, UMR_S 1230, F-35000 Rennes, France; (G.M.); (M.S.)
| | - Chloé Silard
- INSERM, BRM (Bacterial Regulatory RNAs and Medicine), University Rennes, UMR_S 1230, F-35000 Rennes, France; (C.S.); (A.R.)
| | - Marie Suriray
- CHU Rennes, INSERM, BRM (Bacterial Regulatory RNAs and Medicine), SB2H (Service de Bactériologie Hygiène-Hospitalière), University Rennes, UMR_S 1230, F-35000 Rennes, France; (G.M.); (M.S.)
| | - Astrid Rouillon
- INSERM, BRM (Bacterial Regulatory RNAs and Medicine), University Rennes, UMR_S 1230, F-35000 Rennes, France; (C.S.); (A.R.)
| | - Yoann Augagneur
- INSERM, BRM (Bacterial Regulatory RNAs and Medicine), University Rennes, UMR_S 1230, F-35000 Rennes, France; (C.S.); (A.R.)
- Correspondence: ; Tel.: +33-223234631
| |
Collapse
|
8
|
Le Neindre K, Dejoies L, Reissier S, Guérin F, Felden B, Cattoir V. Small RNA-mediated regulation of the tet(M) resistance gene expression in Enterococcus faecium. Res Microbiol 2022; 173:103941. [PMID: 35395390 DOI: 10.1016/j.resmic.2022.103941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/24/2022] [Accepted: 03/25/2022] [Indexed: 11/24/2022]
Abstract
We investigated the role of a novel small RNA expressed in Enterococcus faecium (named Ern0030). We revealed that ern0030 was encoded within the 5'untranslated region of tet(M), a gene conferring tetracycline resistance through ribosomal protection. By RACE mapping, we accurately determined the boundaries of ern0030, which corresponded to Ptet. This upstream sequence of tet(M), Ptet, was previously described within transcriptional attenuation mechanism. Here, Northern blot analyses revealed three transcripts of different lengths (ca. 230, 150 and 100 nucleotides) expressed from Ptet. Phenotypically, the total deletion of ern0030 conferred a decrease in tetracycline MICs that was consistent with gene expression data showing no significant tet(M) induction under tetracycline SIC in ern0030-deleted mutant as opposed to a 10-fold increase of tet(M) expression in the wild-type strain. We investigated the transcriptional attenuation mechanism by toeprint assay. Whereas the expected tet(M) RBS was detected, the RBS of the putative leader peptide was not highlighted by toeprint assay, suggesting the transcriptional attenuation was unlikely. Here, we demonstrate that Ern0030 has a role in regulation of tet(M) expression and propose a novel model of tet(M) regulation alternative or complementary to transcriptional attenuation.
Collapse
Affiliation(s)
- Killian Le Neindre
- Unité Inserm U1230, Université de Rennes 1, Rennes, France; Service de Bactériologie-Hygiène hospitalière, CHU de Rennes, Rennes, France.
| | - Loren Dejoies
- Unité Inserm U1230, Université de Rennes 1, Rennes, France; Service de Bactériologie-Hygiène hospitalière, CHU de Rennes, Rennes, France.
| | | | - François Guérin
- Service de Bactériologie-Hygiène hospitalière, CHU de Rennes, Rennes, France; CNR de la Résistance aux Antibiotiques (laboratoire associé 'Entérocoques'), Rennes, France.
| | - Brice Felden
- Unité Inserm U1230, Université de Rennes 1, Rennes, France.
| | - Vincent Cattoir
- Unité Inserm U1230, Université de Rennes 1, Rennes, France; Service de Bactériologie-Hygiène hospitalière, CHU de Rennes, Rennes, France; CNR de la Résistance aux Antibiotiques (laboratoire associé 'Entérocoques'), Rennes, France.
| |
Collapse
|
9
|
Zou J, Peng B, Qu J, Zheng J. Are Bacterial Persisters Dormant Cells Only? Front Microbiol 2022; 12:708580. [PMID: 35185807 PMCID: PMC8847742 DOI: 10.3389/fmicb.2021.708580] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial persisters are a sub-population of phenotypic variants that tolerate high concentrations of antibiotics within the genetically homogeneous cells. They resume division upon the removal of drugs. Bacterial persistence is one of major causes of antibiotic treatment failure and recurrent infection. Cell dormancy, triggered by toxin/antitoxin pair, (p)ppGpp, SOS response and ATP levels, is known to be the mechanistic basis for persistence. However, recent studies have demonstrated that bacteria with active metabolism can maintain persistence by lowering intracellular antibiotic concentration via an efflux pump. Additionally, others and our work have showed that cell wall deficient bacteria (CWDB), including both L-form and spheroplasts that produced by β-lactam antibiotics, are associated with antibiotic persistence. They are not dormant cells as their cell walls have been completely damaged. In this review, we discuss the various types of persisters and highlight the contribution of non-walled bacteria on bacterial persistence.
Collapse
Affiliation(s)
- Jin Zou
- Department of Clinical Laboratory, The Third People's Hospital of Shenzhen, Southern University of Science and Technology, National Clinical Research Center for Infectious Diseases, Shenzhen, China.,Faculty of Health Sciences, University of Macau, Zhuhai, Macau SAR, China
| | - Bo Peng
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Jiuxin Qu
- Department of Clinical Laboratory, The Third People's Hospital of Shenzhen, Southern University of Science and Technology, National Clinical Research Center for Infectious Diseases, Shenzhen, China
| | - Jun Zheng
- Faculty of Health Sciences, University of Macau, Zhuhai, Macau SAR, China.,Institute of Translational Medicine, University of Macau, Zhuhai, Macau SAR, China
| |
Collapse
|
10
|
Abstract
SarA, a transcriptional regulator of Staphylococcus aureus, is a major global regulatory system that coordinates the expression of target genes involved in its pathogenicity. Various studies have identified a large number of SarA target genes, but an in-depth characterization of the sarA regulon, including small regulatory RNAs (sRNAs), has not yet been done. In this study, we utilized transcriptome sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq) to determine a comprehensive list of SarA-regulated targets, including both mRNAs and sRNAs. RNA-Seq analysis indicated 390 mRNAs and 51 sRNAs differentially expressed in a ΔsarA mutant, while ChIP-Seq revealed 354 mRNAs and 55 sRNA targets in the S. aureus genome. We confirmed the authenticity of several novel SarA targets by Northern blotting and electrophoretic mobility shift assays. Among them, we characterized repression of sprG2, a gene that encodes the toxin of a type I toxin-antitoxin system, indicating a multilayer lockdown of toxin expression by both SarA and its cognate antitoxin, SprF2. Finally, a novel SarA consensus DNA binding sequence was generated using the upstream promoter sequences of 15 novel SarA-regulated sRNA targets. A genome-wide scan with a deduced SarA motif enabled the discovery of new potential SarA target genes which were not identified in our RNA-Seq and ChIP-Seq analyses. The strength of this new consensus was confirmed with one predicted sRNA target. The RNA-Seq and ChIP-Seq combinatory analysis gives a snapshot of the regulation, whereas bioinformatic analysis reveals a permanent view of targets based on sequence. Altogether these experimental and in silico methodologies are effective to characterize transcriptional factor (TF) regulons and functions. IMPORTANCEStaphylococcus aureus, a commensal and opportunist pathogen, is responsible for a large number of human and animal infections, from benign to severe. Gene expression adaptation during infection requires a complex network of regulators, including transcriptional factors (TF) and sRNAs. TF SarA influences virulence, metabolism, biofilm formation, and resistance to some antibiotics. SarA directly regulates expression of around 20 mRNAs and a few sRNAs. Here, we combined high-throughput expression screening methods combined with binding assays and bioinformatics for an in-depth investigation of the SarA regulon. This combinatory approach allowed the identification of 85 unprecedented mRNAs and sRNAs targets, with at least 14 being primary. Among novel SarA direct targets, we characterized repression of sprG2, a gene that encodes the toxin of a toxin-antitoxin system, indicating a multilayer lockdown of toxin expression by both SarA and its cognate antitoxin, SprF2.
Collapse
|
11
|
Hossain T, Deter HS, Peters EJ, Butzin NC. Antibiotic tolerance, persistence, and resistance of the evolved minimal cell, Mycoplasma mycoides JCVI-Syn3B. iScience 2021; 24:102391. [PMID: 33997676 PMCID: PMC8091054 DOI: 10.1016/j.isci.2021.102391] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 02/01/2021] [Accepted: 03/31/2021] [Indexed: 12/22/2022] Open
Abstract
Antibiotic resistance is a growing problem, but bacteria can evade antibiotic treatment via tolerance and persistence. Antibiotic persisters are a small subpopulation of bacteria that tolerate antibiotics due to a physiologically dormant state. Hence, persistence is considered a major contributor to the evolution of antibiotic-resistant and relapsing infections. Here, we used the synthetically developed minimal cell Mycoplasma mycoides JCVI-Syn3B to examine essential mechanisms of antibiotic survival. The minimal cell contains only 473 genes, and most genes are essential. Its reduced complexity helps to reveal hidden phenomenon and fundamental biological principles can be explored because of less redundancy and feedback between systems compared to natural cells. We found that Syn3B evolves antibiotic resistance to different types of antibiotics expeditiously. The minimal cell also tolerates and persists against multiple antibiotics. It contains a few already identified persister-related genes, although lacking many systems previously linked to persistence (e.g. toxin-antitoxin systems, ribosome hibernation genes).
Collapse
Affiliation(s)
- Tahmina Hossain
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57006, USA
| | - Heather S. Deter
- Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Eliza J. Peters
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57006, USA
| | - Nicholas C. Butzin
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57006, USA
| |
Collapse
|
12
|
Sarpong DD, Murphy ER. RNA Regulated Toxin-Antitoxin Systems in Pathogenic Bacteria. Front Cell Infect Microbiol 2021; 11:661026. [PMID: 34084755 PMCID: PMC8167048 DOI: 10.3389/fcimb.2021.661026] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 04/29/2021] [Indexed: 01/05/2023] Open
Abstract
The dynamic host environment presents a significant hurdle that pathogenic bacteria must overcome to survive and cause diseases. Consequently, these organisms have evolved molecular mechanisms to facilitate adaptation to environmental changes within the infected host. Small RNAs (sRNAs) have been implicated as critical regulators of numerous pathways and systems in pathogenic bacteria, including that of bacterial Toxin-Antitoxin (TA) systems. TA systems are typically composed of two factors, a stable toxin, and a labile antitoxin which functions to protect against the potentially deleterious activity of the associated toxin. Of the six classes of bacterial TA systems characterized to date, the toxin component is always a protein. Type I and Type III TA systems are unique in that the antitoxin in these systems is an RNA molecule, whereas the antitoxin in all other TA systems is a protein. Though hotly debated, the involvement of TA systems in bacterial physiology is recognized by several studies, with the Type II TA system being the most extensively studied to date. This review focuses on RNA-regulated TA systems, highlighting the role of Type I and Type III TA systems in several pathogenic bacteria.
Collapse
Affiliation(s)
- David D. Sarpong
- Department of Biological Sciences, Ohio University, Athens, OH, United States
- Infectious and Tropical Diseases Institute, Ohio University, Athens, OH, United States
- Molecular and Cellular Biology Program, Ohio University, Athens, OH, United States
| | - Erin R. Murphy
- Infectious and Tropical Diseases Institute, Ohio University, Athens, OH, United States
- Molecular and Cellular Biology Program, Ohio University, Athens, OH, United States
- Department of Biomedical Sciences, Ohio University, Heritage College of Osteopathic Medicine, Athens, OH, United States
| |
Collapse
|
13
|
Chlebicka K, Bonar E, Suder P, Ostyn E, Felden B, Wladyka B, Pinel-Marie ML. Impacts of the Type I Toxin-Antitoxin System, SprG1/SprF1, on Staphylococcus aureus Gene Expression. Genes (Basel) 2021; 12:genes12050770. [PMID: 34070083 PMCID: PMC8158120 DOI: 10.3390/genes12050770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/14/2021] [Accepted: 05/16/2021] [Indexed: 11/16/2022] Open
Abstract
Type I toxin-antitoxin (TA) systems are widespread genetic modules in bacterial genomes. They express toxic peptides whose overexpression leads to growth arrest or cell death, whereas antitoxins regulate the expression of toxins, acting as labile antisense RNAs. The Staphylococcus aureus (S. aureus) genome contains and expresses several functional type I TA systems, but their biological functions remain unclear. Here, we addressed and challenged experimentally, by proteomics, if the type I TA system, the SprG1/SprF1 pair, influences the overall gene expression in S. aureus. Deleted and complemented S. aureus strains were analyzed for their proteomes, both intracellular and extracellular, during growth. Comparison of intracellular proteomes among the strains points to the SprF1 antitoxin as moderately downregulating protein expression. In the strain naturally expressing the SprG1 toxin, cytoplasmic proteins are excreted into the medium, but this is not due to unspecific cell leakages. Such a toxin-driven release of the cytoplasmic proteins may modulate the host inflammatory response that, in turn, could amplify the S. aureus infection spread.
Collapse
Affiliation(s)
- Kinga Chlebicka
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland; (K.C.); (E.B.)
| | - Emilia Bonar
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland; (K.C.); (E.B.)
| | - Piotr Suder
- Department of Analytical Chemistry and Biochemistry, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, 31-007 Krakow, Poland;
| | - Emeline Ostyn
- Inserm, BRM [Bacterial Regulatory RNAs and Medicine]—UMR_S 1230, 35000 Rennes, France;
| | - Brice Felden
- Inserm, BRM [Bacterial Regulatory RNAs and Medicine]—UMR_S 1230, 35000 Rennes, France;
| | - Benedykt Wladyka
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland; (K.C.); (E.B.)
- Correspondence: (B.W.); (M.-L.P.-M.); Tel.: +48-126646511 (B.W.); +33-223234850 (M.-L.P.-M.)
| | - Marie-Laure Pinel-Marie
- Inserm, BRM [Bacterial Regulatory RNAs and Medicine]—UMR_S 1230, 35000 Rennes, France;
- Correspondence: (B.W.); (M.-L.P.-M.); Tel.: +48-126646511 (B.W.); +33-223234850 (M.-L.P.-M.)
| |
Collapse
|
14
|
Pinel-Marie ML, Brielle R, Riffaud C, Germain-Amiot N, Polacek N, Felden B. RNA antitoxin SprF1 binds ribosomes to attenuate translation and promote persister cell formation in Staphylococcus aureus. Nat Microbiol 2021; 6:209-220. [PMID: 33398097 DOI: 10.1038/s41564-020-00819-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 10/20/2020] [Indexed: 01/28/2023]
Abstract
Persister cells are a subpopulation of transiently antibiotic-tolerant bacteria associated with chronic infection and antibiotic treatment failure. Toxin-antitoxin systems have been linked to persister cell formation but the molecular mechanisms leading to bacterial persistence are mostly unknown. Here, we show that SprF1, a type I antitoxin, associates with translating ribosomes from the major human pathogen Staphylococcus aureus to reduce the pathogen's overall protein synthesis during growth. Under hyperosmotic stress, SprF1 levels increase due to enhanced stability, accumulate on polysomes and attenuate protein synthesis. Using an internal 6-nucleotide sequence on its 5'-end, SprF1 binds ribosomes and interferes with initiator transfer RNA binding, thus reducing translation initiation. An excess of messenger RNA displaces the ribosome-bound antitoxin, freeing the ribosomes for new translation cycles; however, this RNA antitoxin can also displace ribosome-bound mRNA. This translation attenuation mechanism, mediated by an RNA antitoxin, promotes antibiotic persister cell formation. The untranslated SprF1 is a dual-function RNA antitoxin that represses toxin expression by its 3'-end and fine-tunes overall bacterial translation via its 5'-end. These findings demonstrate a general function for a bacterial RNA antitoxin beyond protection from toxicity. They also highlight an RNA-guided molecular process that influences antibiotic persister cell formation.
Collapse
Affiliation(s)
- Marie-Laure Pinel-Marie
- Institut National de la Santé et de la Recherche Médicale, Bacterial Regulatory RNAs and Medicine UMR_S 1230, Rennes, France.
| | - Régine Brielle
- Institut National de la Santé et de la Recherche Médicale, Bacterial Regulatory RNAs and Medicine UMR_S 1230, Rennes, France
| | - Camille Riffaud
- Institut National de la Santé et de la Recherche Médicale, Bacterial Regulatory RNAs and Medicine UMR_S 1230, Rennes, France
| | - Noëlla Germain-Amiot
- Institut National de la Santé et de la Recherche Médicale, Bacterial Regulatory RNAs and Medicine UMR_S 1230, Rennes, France
| | - Norbert Polacek
- Department of Chemistry and Biochemistry, Bern University, Bern, Switzerland
| | - Brice Felden
- Institut National de la Santé et de la Recherche Médicale, Bacterial Regulatory RNAs and Medicine UMR_S 1230, Rennes, France.
| |
Collapse
|
15
|
A peptide of a type I toxin-antitoxin system induces Helicobacter pylori morphological transformation from spiral shape to coccoids. Proc Natl Acad Sci U S A 2020; 117:31398-31409. [PMID: 33229580 DOI: 10.1073/pnas.2016195117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Toxin-antitoxin systems are found in many bacterial chromosomes and plasmids with roles ranging from plasmid stabilization to biofilm formation and persistence. In these systems, the expression/activity of the toxin is counteracted by an antitoxin, which, in type I systems, is an antisense RNA. While the regulatory mechanisms of these systems are mostly well defined, the toxins' biological activity and expression conditions are less understood. Here, these questions were investigated for a type I toxin-antitoxin system (AapA1-IsoA1) expressed from the chromosome of the human pathogen Helicobacter pylori We show that expression of the AapA1 toxin in H. pylori causes growth arrest associated with rapid morphological transformation from spiral-shaped bacteria to round coccoid cells. Coccoids are observed in patients and during in vitro growth as a response to different stress conditions. The AapA1 toxin, first molecular effector of coccoids to be identified, targets H. pylori inner membrane without disrupting it, as visualized by cryoelectron microscopy. The peptidoglycan composition of coccoids is modified with respect to spiral bacteria. No major changes in membrane potential or adenosine 5'-triphosphate (ATP) concentration result from AapA1 expression, suggesting coccoid viability. Single-cell live microscopy tracking the shape conversion suggests a possible association of this process with cell elongation/division interference. Oxidative stress induces coccoid formation and is associated with repression of the antitoxin promoter and enhanced processing of its transcript, leading to an imbalance in favor of AapA1 toxin expression. Our data support the hypothesis of viable coccoids with characteristics of dormant bacteria that might be important in H. pylori infections refractory to treatment.
Collapse
|
16
|
Tandon H, Melarkode Vattekatte A, Srinivasan N, Sandhya S. Molecular and Structural Basis of Cross-Reactivity in M. tuberculosis Toxin-Antitoxin Systems. Toxins (Basel) 2020; 12:E481. [PMID: 32751054 PMCID: PMC7472061 DOI: 10.3390/toxins12080481] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/21/2020] [Accepted: 06/23/2020] [Indexed: 01/12/2023] Open
Abstract
Mycobacterium tuberculosis genome encodes over 80 toxin-antitoxin (TA) systems. While each toxin interacts with its cognate antitoxin, the abundance of TA systems presents an opportunity for potential non-cognate interactions. TA systems mediate manifold interactions to manage pathogenicity and stress response network of the cell and non-cognate interactions may play vital roles as well. To address if non-cognate and heterologous interactions are feasible and to understand the structural basis of their interactions, we have performed comprehensive computational analyses on the available 3D structures and generated structural models of paralogous M. tuberculosis VapBC and MazEF TA systems. For a majority of the TA systems, we show that non-cognate toxin-antitoxin interactions are structurally incompatible except for complexes like VapBC15 and VapBC11, which show similar interfaces and potential for cross-reactivity. For TA systems which have been experimentally shown earlier to disfavor non-cognate interactions, we demonstrate that they are structurally and stereo-chemically incompatible. For selected TA systems, our detailed structural analysis identifies specificity conferring residues. Thus, our work improves the current understanding of TA interfaces and generates a hypothesis based on congenial binding site, geometric complementarity, and chemical nature of interfaces. Overall, our work offers a structure-based explanation for non-cognate toxin-antitoxin interactions in M. tuberculosis.
Collapse
Affiliation(s)
- Himani Tandon
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India; (H.T.); (A.M.V.)
| | - Akhila Melarkode Vattekatte
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India; (H.T.); (A.M.V.)
- Biologie Intégrée du Globule Rouge UMR_S1134, INSERM, Université Paris, Université de la Réunion, Université des Antilles, F-75739 Paris, France
- Laboratoire d’Excellence GR-Ex, F-75739 Paris, France
- Faculté des Sciences et Technologies, Saint Denis Messag, F-97715 La Réunion, France
- Institut National de la Transfusion Sanguine (INTS), F-75739 Paris, France
| | - Narayanaswamy Srinivasan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India; (H.T.); (A.M.V.)
| | - Sankaran Sandhya
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India; (H.T.); (A.M.V.)
| |
Collapse
|
17
|
Cross-Regulations between Bacterial Toxin-Antitoxin Systems: Evidence of an Interconnected Regulatory Network? Trends Microbiol 2020; 28:851-866. [PMID: 32540313 DOI: 10.1016/j.tim.2020.05.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 12/31/2022]
Abstract
Toxin-antitoxin (TA) systems are ubiquitous among bacteria and include stable toxins whose toxicity can be counteracted by RNA or protein antitoxins. They are involved in multiple functions that range from stability maintenance for mobile genetic elements to stress adaptation. Bacterial chromosomes frequently have multiple homologues of TA system loci, and it is unclear why there are so many of them. In this review we focus on cross-regulations between TA systems, which occur between both homologous and nonhomologous systems, from similar or distinct types, whether encoded from plasmids or chromosomes. In addition to being able to modulate RNA expression levels, cross-regulations between these systems can also influence their toxicity. This suggests the idea that they are involved in an interconnected regulatory network.
Collapse
|
18
|
Germain-Amiot N, Augagneur Y, Camberlein E, Nicolas I, Lecureur V, Rouillon A, Felden B. A novel Staphylococcus aureus cis-trans type I toxin-antitoxin module with dual effects on bacteria and host cells. Nucleic Acids Res 2019; 47:1759-1773. [PMID: 30544243 PMCID: PMC6393315 DOI: 10.1093/nar/gky1257] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 11/29/2018] [Accepted: 12/05/2018] [Indexed: 12/16/2022] Open
Abstract
Bacterial type I toxin–antitoxin (TA) systems are widespread, and consist of a stable toxic peptide whose expression is monitored by a labile RNA antitoxin. We characterized Staphylococcus aureus SprA2/SprA2AS module, which shares nucleotide similarities with the SprA1/SprA1AS TA system. We demonstrated that SprA2/SprA2AS encodes a functional type I TA system, with the cis-encoded SprA2AS antitoxin acting in trans to prevent ribosomal loading onto SprA2 RNA. We proved that both TA systems are distinct, with no cross-regulation between the antitoxins in vitro or in vivo. SprA2 expresses PepA2, a toxic peptide which internally triggers bacterial death. Conversely, although PepA2 does not affect bacteria when it is present in the extracellular medium, it is highly toxic to other host cells such as polymorphonuclear neutrophils and erythrocytes. Finally, we showed that SprA2AS expression is lowered during osmotic shock and stringent response, which indicates that the system responds to specific triggers. Therefore, the SprA2/SprA2AS module is not redundant with SprA1/SprA1AS, and its PepA2 peptide exhibits an original dual mode of action against bacteria and host cells. This suggests an altruistic behavior for S. aureus in which clones producing PepA2 in vivo shall die as they induce cytotoxicity, thereby promoting the success of the community.
Collapse
Affiliation(s)
- Noëlla Germain-Amiot
- Université de Rennes 1, Inserm, BRM (Bacterial Regulatory RNAs and Medicine) UMR_S 1230, 35000 Rennes, France
| | - Yoann Augagneur
- Université de Rennes 1, Inserm, BRM (Bacterial Regulatory RNAs and Medicine) UMR_S 1230, 35000 Rennes, France
| | - Emilie Camberlein
- Université de Rennes 1, Inserm, BRM (Bacterial Regulatory RNAs and Medicine) UMR_S 1230, 35000 Rennes, France
| | - Irène Nicolas
- Université de Rennes 1, Inserm, BRM (Bacterial Regulatory RNAs and Medicine) UMR_S 1230, 35000 Rennes, France
| | - Valérie Lecureur
- Université de Rennes 1, CHU Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail) UMR_S 1085, 35000 Rennes, France
| | - Astrid Rouillon
- Université de Rennes 1, Inserm, BRM (Bacterial Regulatory RNAs and Medicine) UMR_S 1230, 35000 Rennes, France
| | - Brice Felden
- Université de Rennes 1, Inserm, BRM (Bacterial Regulatory RNAs and Medicine) UMR_S 1230, 35000 Rennes, France
| |
Collapse
|
19
|
Soutourina O. Type I Toxin-Antitoxin Systems in Clostridia. Toxins (Basel) 2019; 11:toxins11050253. [PMID: 31064056 PMCID: PMC6563280 DOI: 10.3390/toxins11050253] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 04/30/2019] [Accepted: 05/02/2019] [Indexed: 12/20/2022] Open
Abstract
Type I toxin-antitoxin (TA) modules are abundant in both bacterial plasmids and chromosomes and usually encode a small hydrophobic toxic protein and an antisense RNA acting as an antitoxin. The RNA antitoxin neutralizes toxin mRNA by inhibiting its translation and/or promoting its degradation. This review summarizes our current knowledge of the type I TA modules identified in Clostridia species focusing on the recent findings in the human pathogen Clostridium difficile. More than ten functional type I TA modules have been identified in the genome of this emerging enteropathogen that could potentially contribute to its fitness and success inside the host. Despite the absence of sequence homology, the comparison of these newly identified type I TA modules with previously studied systems in other Gram-positive bacteria, i.e., Bacillus subtilis and Staphylococcus aureus, revealed some important common traits. These include the conservation of characteristic sequence features for small hydrophobic toxic proteins, the localization of several type I TA within prophage or prophage-like regions and strong connections with stress response. Potential functions in the stabilization of genome regions, adaptations to stress conditions and interactions with CRISPR-Cas defence system, as well as promising applications of TA for genome-editing and antimicrobial developments are discussed.
Collapse
Affiliation(s)
- Olga Soutourina
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette CEDEX, France.
| |
Collapse
|
20
|
Bukowski M, Piwowarczyk R, Madry A, Zagorski-Przybylo R, Hydzik M, Wladyka B. Prevalence of Antibiotic and Heavy Metal Resistance Determinants and Virulence-Related Genetic Elements in Plasmids of Staphylococcus aureus. Front Microbiol 2019; 10:805. [PMID: 31068910 PMCID: PMC6491766 DOI: 10.3389/fmicb.2019.00805] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 03/29/2019] [Indexed: 12/16/2022] Open
Abstract
The use of antibiotics on a mass scale, particularly in farming, and their release into the environment has led to a rapid emergence of resistant bacteria. Once emerged, resistance determinants are spread by horizontal gene transfer among strains of the same as well as disparate bacterial species. Their accumulation in free-living as well as livestock and community-associated strains results in the widespread multiple-drug resistance among clinically relevant species posing an increasingly pressing problem in healthcare. One of these clinically relevant species is Staphylococcus aureus, a common cause of hospital and community outbreaks. Among the rich diversity of mobile genetic elements regularly occurring in S. aureus such as phages, pathogenicity islands, and staphylococcal cassette chromosomes, plasmids are the major mean for dissemination of resistance determinants and virulence factors. Unfortunately, a vast number of whole-genome sequencing projects does not aim for complete sequence determination, which results in a disproportionately low number of known complete plasmid sequences. To address this problem we determined complete plasmid sequences derived from 18 poultry S. aureus strains and analyzed the prevalence of antibiotic and heavy metal resistance determinants, genes of virulence factors, as well as genetic elements relevant for their maintenance. Some of the plasmids have been reported before and are being found in clinical isolates of strains typical for humans or human ones of livestock origin. This shows that livestock-associated staphylococci are a significant reservoir of resistance determinants and virulence factors. Nevertheless, nearly half of the plasmids were unknown to date. In this group we found a potentially mobilizable plasmid pPA3 being a unique example of accumulation of resistance determinants and virulence factors likely stabilized by a presence of a toxin–antitoxin system.
Collapse
Affiliation(s)
- Michal Bukowski
- Department of Analytical Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Rafal Piwowarczyk
- Department of Analytical Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Anna Madry
- Department of Analytical Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Rafal Zagorski-Przybylo
- Department of Analytical Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Marcin Hydzik
- Department of Analytical Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Benedykt Wladyka
- Department of Analytical Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland
| |
Collapse
|