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Brown NA, Urban M, Hammond-Kosack KE. The trans-kingdom identification of negative regulators of pathogen hypervirulence. FEMS Microbiol Rev 2016; 40:19-40. [PMID: 26468211 PMCID: PMC4703069 DOI: 10.1093/femsre/fuv042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/30/2015] [Accepted: 09/03/2015] [Indexed: 01/08/2023] Open
Abstract
Modern society and global ecosystems are increasingly under threat from pathogens, which cause a plethora of human, animal, invertebrate and plant diseases. Of increasing concern is the trans-kingdom tendency for increased pathogen virulence that is beginning to emerge in natural, clinical and agricultural settings. The study of pathogenicity has revealed multiple examples of convergently evolved virulence mechanisms. Originally described as rare, but increasingly common, are interactions where a single gene deletion in a pathogenic species causes hypervirulence. This review utilised the pathogen-host interaction database (www.PHI-base.org) to identify 112 hypervirulent mutations from 37 pathogen species, and subsequently interrogates the trans-kingdom, conserved, molecular, biochemical and cellular themes that cause hypervirulence. This study investigates 22 animal and 15 plant pathogens including 17 bacterial and 17 fungal species. Finally, the evolutionary significance and trans-kingdom requirement for negative regulators of hypervirulence and the implication of pathogen hypervirulence and emerging infectious diseases on society are discussed.
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Affiliation(s)
- Neil A Brown
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK
| | - Martin Urban
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK
| | - Kim E Hammond-Kosack
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK
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The Mechanisms of Virulence Regulation by Small Noncoding RNAs in Low GC Gram-Positive Pathogens. Int J Mol Sci 2015; 16:29797-814. [PMID: 26694351 PMCID: PMC4691137 DOI: 10.3390/ijms161226194] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 12/01/2015] [Accepted: 12/04/2015] [Indexed: 11/30/2022] Open
Abstract
The discovery of small noncoding regulatory RNAs (sRNAs) in bacteria has grown tremendously recently, giving new insights into gene regulation. The implementation of computational analysis and RNA sequencing has provided new tools to discover and analyze potential sRNAs. Small regulatory RNAs that act by base-pairing to target mRNAs have been found to be ubiquitous and are the most abundant class of post-transcriptional regulators in bacteria. The majority of sRNA studies has been limited to E. coli and other gram-negative bacteria. However, examples of sRNAs in gram-positive bacteria are still plentiful although the detailed gene regulation mechanisms behind them are not as well understood. Strict virulence control is critical for a pathogen’s survival and many sRNAs have been found to be involved in that process. This review outlines the targets and currently known mechanisms of trans-acting sRNAs involved in virulence regulation in various gram-positive pathogens. In addition, their shared characteristics such as CU interaction motifs, the role of Hfq, and involvement in two-component regulators, riboswitches, quorum sensing, or toxin/antitoxin systems are described.
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Mlynarczyk A, Szymanek-Majchrzak K, Grzybowska W, Durlik M, Deborska-Materkowska D, Paczek L, Chmura A, Swoboda-Kopec E, Tyski S, Mlynarczyk G. Molecular and phenotypic characteristics of methicillin-resistant Staphylococcus aureus strains isolated from hospitalized patients in transplantation wards. Transplant Proc 2015; 46:2579-82. [PMID: 25380870 DOI: 10.1016/j.transproceed.2014.08.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
OBJECTIVES Hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) frequently causes therapeutic problems and provides information about the epidemiological condition of the ward. MATERIALS AND METHODS HA-MRSA isolated from patients on transplantation wards in 1991, 1994, 1996, and from 2005 to 2007 were compared using molecular methods such as restriction fragment length polymorphism-pulse field gel electrophoresis, multilocus sequence typing (MLST), multiplex polymerase chain reaction (PCR) for detection type of staphylococcal chromosomal cassette mec, and PCR for detection. RESULTS The analysis covered HA-MRSA strains, each from a different patient. All organisms were typed using molecular methods. MLST results were compared with an international base. The examined strains belonged to five different worldwide known clonal complexes: CC8 (78%), CC5 (12%), CC1 (4%), CC30 (2%), and CC51 (4%). All could be recognized as representatives of a clonal complex CC8 clones: ST239-III (sequence type 239 and SCCmec type III named EMRSA-1, -4, -11, Brasilian, Hungarian) occurred with a frequency of 35.9%, ST254-IV (EMRSA-10, Hannover) occurred in 33.3%, ST247-I (EMRSA-5,-7, Iberian) occurred in 20.5%, ST241-III (Finland-UK) occurred in 5.15%, and ST8-IV (EMRSA-2,-6) occurred in 5.15%. CONCLUSION The predomination of different clones of HA-MRSA in the particular years was observed. In 1991, the EMRSA-10 (Hannover) clone predominated (53.3%). The Brasilian-Hungarian (EMRSA-1, -4, -11) clone predominated in 1994 (50%) as well as from 2005 to 2007 (41.3%), whereas in 1996 the Iberian clone was most frequent (53.9%).
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Affiliation(s)
- A Mlynarczyk
- Department of Dental Microbiology, Medical University of Warsaw, Warsaw, Poland
| | - K Szymanek-Majchrzak
- Department of Medical Microbiology, Medical University of Warsaw, Warsaw, Poland
| | - W Grzybowska
- Department of Antibiotics and Microbiology, National Medicines Institute, Warsaw, Poland
| | - M Durlik
- Department of Transplant Medicine and Nephrology, Transplantation Institute, Medical University of Warsaw, Warsaw, Poland
| | - D Deborska-Materkowska
- Department of Transplant Medicine and Nephrology, Transplantation Institute, Medical University of Warsaw, Warsaw, Poland
| | - L Paczek
- Department of Immunology, Transplantology and Internal Diseases, Transplantation Institute, Medical University of Warsaw, Warsaw, Poland
| | - A Chmura
- Department of General and Transplantation Surgery, Transplantation Institute, Medical University of Warsaw, Warsaw, Poland
| | - E Swoboda-Kopec
- Department of Dental Microbiology, Medical University of Warsaw, Warsaw, Poland
| | - S Tyski
- Department of Antibiotics and Microbiology, National Medicines Institute, Warsaw, Poland; Department of Pharmaceutical Microbiology, Medical University of Warsaw, Warsaw, Poland
| | - G Mlynarczyk
- Department of Medical Microbiology, Medical University of Warsaw, Warsaw, Poland.
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16S rRNA methyltransferase KsgA contributes to oxidative stress resistance and virulence in Staphylococcus aureus. Biochimie 2015; 119:166-74. [PMID: 26545800 DOI: 10.1016/j.biochi.2015.10.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Accepted: 10/28/2015] [Indexed: 11/21/2022]
Abstract
We previously reported that the rRNA methyltransferases RsmI and RsmH, which are responsible for cytidine dimethylation at position 1402 of 16S rRNA in the decoding center of the ribosome, contribute to Staphylococcus aureus virulence. Here we evaluated other 16S rRNA methyltransferases, including KsgA (RsmA), RsmB/F, RsmC, RsmD, RsmE, and RsmG. Knockout of KsgA, which methylates two adjacent adenosines at positions 1518 and 1519 of 16S rRNA in the intersubunit bridge of the ribosome, attenuated the S. aureus killing ability against silkworms. The ksgA knockout strain was sensitive to oxidative stress and had a lower survival rate in murine macrophages than the parent strain. The ksgA knockout strain exhibited decreased translational fidelity in oxidative stress conditions. Administration of N-acetyl-l-cysteine, a free-radical scavenger, restored the killing ability of the ksgA knockout strain against silkworms. These findings suggest that the methyl-modifications of 16S rRNA by KsgA contribute to maintain ribosome function under oxidative conditions and thus to S. aureus virulence.
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55
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Berlon NR, Qi R, Sharma-Kuinkel BK, Joo HS, Park LP, George D, Thaden JT, Messina JA, Maskarinec SA, Mueller-Premru M, Athan E, Tattevin P, Pericas JM, Woods CW, Otto M, Fowler VG. Clinical MRSA isolates from skin and soft tissue infections show increased in vitro production of phenol soluble modulins. J Infect 2015; 71:447-57. [PMID: 26079275 PMCID: PMC4816458 DOI: 10.1016/j.jinf.2015.06.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/05/2015] [Accepted: 06/08/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Phenol-soluble modulins (PSMs) are amphipathic, pro-inflammatory proteins secreted by most Staphylococcus aureus isolates. This study tested the hypothesis that in vitro PSM production levels are associated with specific clinical phenotypes. METHODS 177 methicillin-resistant S. aureus (MRSA) isolates from infective endocarditis (IE), skin and soft tissue infection (SSTI), and hospital-acquired/ventilator-associated pneumonia (HAP) were matched by geographic origin, then genotyped using spa-typing. In vitro PSM production was measured by high performance liquid chromatography/mass spectrometry. Statistical analysis was performed using Chi-squared or Kruskal-Wallis tests as appropriate. RESULTS Spa type 1 was significantly more common in SSTI isolates (62.7% SSTI; 1.7% IE; 16.9% HAP; p < 0.0001) while HAP and IE isolates were more commonly spa type 2 (0% SSTI; 37.3% IE; 40.7% HAP; p < 0.0001). USA300 isolates produced the highest levels of PSMs in vitro. SSTI isolates produced significantly higher quantities of PSMα1-4, PSMβ1, and δ-toxin than other isolates (p < 0.001). These findings persisted when USA300 isolates were excluded from analysis. CONCLUSIONS Increased in vitro production of PSMs is associated with an SSTI clinical source. This significant association persisted after exclusion of USA300 genotype isolates from analysis, suggesting that PSMs play a particularly important role in the pathogenesis of SSTI as compared to other infection types.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Eugene Athan
- Barwon Health, Deakin University, VIC, Australia
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Modulation of ccrAB Expression and SCCmec Excision by an Inverted Repeat Element and SarS in Methicillin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2015; 59:6223-32. [PMID: 26248371 DOI: 10.1128/aac.01041-15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/18/2015] [Indexed: 01/06/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a notorious human pathogen that can cause a broad spectrum of infections. MRSA strains are resistant to almost the entire family of β-lactam antibiotics due to the acquisition of staphylococcal cassette chromosome mec (SCCmec). The chromosome cassette recombinases A and B, encoded by ccrAB genes located on SCCmec, play a key role in the excision of SCCmec. Studies have shown that ccrAB genes are expressed in only a minority of cells, suggesting the involvement of a subtle regulatory mechanism in ccrAB expression which has not been uncovered. Here, we found that an inverted repeat (IR) element, existing extensively and conservatively within the ccrAB promoter of different SCCmec types, played a repressive role in ccrAB expression and SCCmec excision in MRSA strain N315. Replacement of the IR sequence led to a significant increase in ccrAB expression and curing of SCCmec from strain N315 cells. In addition, we identified the transcriptional regulator SarS using DNA-affinity chromatography and further demonstrated that SarS can bind to the IR sequence and upregulate ccrAB expression and SCCmec excision. These findings reveal a molecular mechanism regulating ccrAB expression and SCCmec excision and may provide mechanic insights into the lateral transfer of SCCmec and spread of antibiotic resistance in S. aureus.
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57
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Yoshikai H, Kizaki H, Saito Y, Omae Y, Sekimizu K, Kaito C. Multidrug-Resistance Transporter AbcA Secretes Staphylococcus aureus Cytolytic Toxins. J Infect Dis 2015; 213:295-304. [PMID: 26160745 DOI: 10.1093/infdis/jiv376] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 07/03/2015] [Indexed: 12/21/2022] Open
Abstract
Phenol-soluble modulins (PSMs) are Staphylococcus aureus cytolytic toxins that lyse erythrocytes and neutrophils and have important functions in the S. aureus infectious process. The molecular mechanisms of PSM secretion, however, are not well understood. Here we report that knockout of the multidrug-resistance ABC transporter AbcA, which contributes to S. aureus resistance against antibiotics and chemicals, diminished the secreted amount of PSM, leading to the accumulation of PSM in the intracellular fraction. The amount of PSM in the culture supernatants of the abcA knockout mutants was restored by introduction of the wild-type abcA gene, whereas it was not completely restored by introduction of mutant abcA genes encoding AbcA mutant proteins carrying amino acid substitutions in the adenosine triphosphate binding motifs. The abcA knockout mutant exhibited attenuated virulence in a mouse systemic infection model. These findings suggest that the multidrug resistance transporter AbcA secretes PSMs and contributes to S. aureus virulence.
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Affiliation(s)
- Hirono Yoshikai
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
| | - Hayato Kizaki
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
| | - Yuki Saito
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
| | - Yosuke Omae
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
| | - Kazuhisa Sekimizu
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
| | - Chikara Kaito
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
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Kreth J, Liu N, Chen Z, Merritt J. RNA regulators of host immunity and pathogen adaptive responses in the oral cavity. Microbes Infect 2015; 17:493-504. [PMID: 25790757 PMCID: PMC4485933 DOI: 10.1016/j.micinf.2015.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/05/2015] [Accepted: 03/07/2015] [Indexed: 12/15/2022]
Abstract
The recent explosion of RNA-seq studies has resulted in a newfound appreciation for the importance of riboregulatory RNAs in the posttranscriptional control of eukaryotic and prokaryotic genetic networks. The current review will explore the role of trans-riboregulatory RNAs in various adaptive responses of host and pathogen in the oral cavity.
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Affiliation(s)
- Jens Kreth
- OUHSC Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA; OUHSC College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
| | - Nan Liu
- Department of Restorative Dentistry, Oregon Health and Science University, 2730 SW Moody Ave., Portland, OR, 97201-5042, USA
| | - Zhiyun Chen
- OUHSC Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Justin Merritt
- Department of Restorative Dentistry, Oregon Health and Science University, 2730 SW Moody Ave., Portland, OR, 97201-5042, USA.
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59
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Steinig EJ, Andersson P, Harris SR, Sarovich DS, Manoharan A, Coupland P, Holden MTG, Parkhill J, Bentley SD, Robinson DA, Tong SYC. Single-molecule sequencing reveals the molecular basis of multidrug-resistance in ST772 methicillin-resistant Staphylococcus aureus. BMC Genomics 2015; 16:388. [PMID: 25981586 PMCID: PMC4432960 DOI: 10.1186/s12864-015-1599-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/28/2015] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-associated infection, but there is growing awareness of the emergence of multidrug-resistant lineages in community settings around the world. One such lineage is ST772-MRSA-V, which has disseminated globally and is increasingly prevalent in India. Here, we present the complete genome sequence of DAR4145, a strain of the ST772-MRSA-V lineage from India, and investigate its genomic characteristics in regards to antibiotic resistance and virulence factors. RESULTS Sequencing using single-molecule real-time technology resulted in the assembly of a single continuous chromosomal sequence, which was error-corrected, annotated and compared to nine draft genome assemblies of ST772-MRSA-V from Australia, Malaysia and India. We discovered numerous and redundant resistance genes associated with mobile genetic elements (MGEs) and known core genome mutations that explain the highly antibiotic resistant phenotype of DAR4145. Staphylococcal toxins and superantigens, including the leukotoxin Panton-Valentinin Leukocidin, were predominantly associated with genomic islands and the phage φ-IND772PVL. Some of these mobile resistance and virulence factors were variably present in other strains of the ST772-MRSA-V lineage. CONCLUSIONS The genomic characteristics presented here emphasize the contribution of MGEs to the emergence of multidrug-resistant and highly virulent strains of community-associated MRSA. Antibiotic resistance was further augmented by chromosomal mutations and redundancy of resistance genes. The complete genome of DAR4145 provides a valuable resource for future investigations into the global dissemination and phylogeography of ST772-MRSA-V.
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Affiliation(s)
- Eike J Steinig
- Menzies School of Health Research, Darwin, Northern Territory, Australia.
| | - Patiyan Andersson
- Menzies School of Health Research, Darwin, Northern Territory, Australia.
| | - Simon R Harris
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.
| | - Derek S Sarovich
- Menzies School of Health Research, Darwin, Northern Territory, Australia.
| | - Anand Manoharan
- Pushpagiri Research Center, Pushpagiri Institute of Medical Sciences and Research Center, Thiruvalla, India.
| | - Paul Coupland
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.
| | | | - Julian Parkhill
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.
| | - Stephen D Bentley
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.
| | - D Ashley Robinson
- Department of Microbiology, University of Mississippi Medical Center, Jackson, MS, USA.
| | - Steven Y C Tong
- Menzies School of Health Research, Darwin, Northern Territory, Australia.
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Kyuma T, Kimura S, Hanada Y, Suzuki T, Sekimizu K, Kaito C. Ribosomal RNA methyltransferases contribute toStaphylococcus aureusvirulence. FEBS J 2015; 282:2570-84. [DOI: 10.1111/febs.13302] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 04/03/2015] [Accepted: 04/16/2015] [Indexed: 12/13/2022]
Affiliation(s)
- Tatsuhiko Kyuma
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Japan
| | - Satoshi Kimura
- Department of Chemistry and Biotechnology; Graduate School of Engineering; The University of Tokyo; Japan
| | - Yuichi Hanada
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology; Graduate School of Engineering; The University of Tokyo; Japan
| | - Kazuhisa Sekimizu
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Japan
| | - Chikara Kaito
- Laboratory of Microbiology; Graduate School of Pharmaceutical Sciences; The University of Tokyo; Japan
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Durand S, Tomasini A, Braun F, Condon C, Romby P. sRNA and mRNA turnover in Gram-positive bacteria. FEMS Microbiol Rev 2015; 39:316-30. [PMID: 25934118 DOI: 10.1093/femsre/fuv007] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2015] [Indexed: 01/18/2023] Open
Abstract
It is widely recognized that RNA degradation plays a critical role in gene regulation when fast adaptation of cell growth is required to respond to stress and changing environmental conditions. Bacterial ribonucleases acting alone or in concert with various trans-acting regulatory factors are important mediators of RNA degradation. Here, we will give an overview of what is known about ribonucleases in several Gram-positive bacteria, their specificities and mechanisms of action. In addition, we will illustrate how sRNAs act in a coordinated manner with ribonucleases to regulate the turnover of particular mRNA targets, and the complex interplay existing between the ribosome, the ribonucleases and RNAs.
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Affiliation(s)
- Sylvain Durand
- CNRS FRE 3630 (affiliated with Univ. Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Arnaud Tomasini
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 15 rue René Descartes, F-67084 Strasbourg, France
| | - Frédérique Braun
- CNRS FRE 3630 (affiliated with Univ. Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Ciarán Condon
- CNRS FRE 3630 (affiliated with Univ. Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Pascale Romby
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 15 rue René Descartes, F-67084 Strasbourg, France
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agr dysfunction affects staphylococcal cassette chromosome mec type-dependent clinical outcomes in methicillin-resistant Staphylococcus aureus bacteremia. Antimicrob Agents Chemother 2015; 59:3125-32. [PMID: 25779574 DOI: 10.1128/aac.04962-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/05/2015] [Indexed: 12/30/2022] Open
Abstract
Staphylococcal cassette chromosome mec element (SCCmec) type-dependent clinical outcomes may vary due to geographical variation in the presence of virulence determinants. We compared the microbiological factors and mortality attributed to methicillin-resistant Staphylococcus aureus (MRSA) bacteremia between SCCmec types II/III and type IV. All episodes of MRSA bacteremia in a tertiary-care hospital (South Korea) over a 4.5-year period were reviewed. We studied the microbiological factors associated with all blood MRSA isolates, including spa type, agr type, agr dysfunction, and the genes for Panton-Valentine leukocidin (PVL) and phenol-soluble modulin (PSM)-mec, in addition to SCCmec type. Of 195 cases, 137 involved SCCmec types II/III, and 58 involved type IV. The mortality attributed to MRSA bacteremia was less frequent among the SCCmec type IV (5/58) than that among types II/III (39/137, P = 0.002). This difference remained significant when adjusted for clinical factors (adjusted odds ratio [aOR], 0.14; 95% confidence interval [CI], 0.04 to 0.49; P = 0.002). Of the microbiological factors tested, agr dysfunction was the only significant factor that showed different positivity between the SCCmec types, and it was independently associated with MRSA bacteremia-attributed mortality (aOR, 4.71; 95% CI, 1.72 to 12.92; P = 0.003). SCCmec type IV is associated with lower MRSA bacteremia-attributed mortality than are types II/III, which might be explained by the high rate of agr dysfunction in SCCmec types II/III in South Korea.
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63
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McCarthy H, Rudkin JK, Black NS, Gallagher L, O'Neill E, O'Gara JP. Methicillin resistance and the biofilm phenotype in Staphylococcus aureus. Front Cell Infect Microbiol 2015; 5:1. [PMID: 25674541 PMCID: PMC4309206 DOI: 10.3389/fcimb.2015.00001] [Citation(s) in RCA: 240] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 01/05/2015] [Indexed: 12/05/2022] Open
Abstract
Antibiotic resistance and biofilm-forming capacity contribute to the success of Staphylococcus aureus as a human pathogen in both healthcare and community settings. These virulence factors do not function independently of each other and the biofilm phenotype expressed by clinical isolates of S. aureus is influenced by acquisition of the methicillin resistance gene mecA. Methicillin-sensitive S. aureus (MSSA) strains commonly produce an icaADBC operon-encoded polysaccharide intercellular adhesin (PIA)-dependent biofilm. In contrast, the release of extracellular DNA (eDNA) and cell surface expression of a number of sortase-anchored proteins, and the major autolysin have been implicated in the biofilm phenotype of methicillin-resistant S. aureus (MRSA) isolates. Expression of high level methicillin resistance in a laboratory MSSA strain resulted in (i) repression of PIA-mediated biofilm production, (ii) down-regulation of the accessory gene regulator (Agr) system, and (iii) attenuation of virulence in murine sepsis and device infection models. Here we review the mechanisms of MSSA and MRSA biofilm production and the relationships between antibiotic resistance, biofilm and virulence gene regulation in S. aureus.
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Affiliation(s)
- Hannah McCarthy
- Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Ireland
| | - Justine K Rudkin
- Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Ireland
| | - Nikki S Black
- Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Ireland
| | - Laura Gallagher
- Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Ireland
| | - Eoghan O'Neill
- Department of Clinical Microbiology, Royal College of Surgeons in Ireland Dublin, Ireland
| | - James P O'Gara
- Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Ireland
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65
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Le KY, Dastgheyb S, Ho TV, Otto M. Molecular determinants of staphylococcal biofilm dispersal and structuring. Front Cell Infect Microbiol 2014; 4:167. [PMID: 25505739 PMCID: PMC4244807 DOI: 10.3389/fcimb.2014.00167] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 10/27/2014] [Indexed: 11/30/2022] Open
Abstract
Staphylococci are frequently implicated in human infections, and continue to pose a therapeutic dilemma due to their ability to form deeply seated microbial communities, known as biofilms, on the surfaces of implanted medical devices and host tissues. Biofilm development has been proposed to occur in three stages: (1) attachment, (2) proliferation/structuring, and (3) detachment/dispersal. Although research within the last several decades has implicated multiple molecules in the roles as effectors of staphylococcal biofilm proliferation/structuring and detachment/dispersal, to date, only phenol soluble modulins (PSMs) have been consistently demonstrated to serve in this role under both in vitro and in vivo settings. PSMs are regulated directly through a density-dependent manner by the accessory gene regulator (Agr) system. They disrupt the non-covalent forces holding the biofilm extracellular matrix together, which is necessary for the formation of channels, a process essential for the delivery of nutrients to deeper biofilm layers, and for dispersal/dissemination of clusters of biofilm to distal organs in acute infection. Given their relevance in both acute and chronic biofilm-associated infections, the Agr system and the psm genes hold promise as potential therapeutic targets.
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Affiliation(s)
- Katherine Y Le
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health Bethesda, MD, USA ; Division of Hospital Internal Medicine, Department of Medicine, Mayo Clinic College of Medicine Rochester, MN, USA
| | - Sana Dastgheyb
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health Bethesda, MD, USA ; Department of Orthopedic Surgery, Thomas Jefferson University School of Medicine Philadelphia, PA, USA
| | - Trung V Ho
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health Bethesda, MD, USA ; Uniformed Services University of the Health and Sciences, School of Medicine Bethesda, MD, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health Bethesda, MD, USA
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Benson MA, Ohneck EA, Ryan C, Alonzo F, Smith H, Narechania A, Kolokotronis SO, Satola SW, Uhlemann AC, Sebra R, Deikus G, Shopsin B, Planet PJ, Torres VJ. Evolution of hypervirulence by a MRSA clone through acquisition of a transposable element. Mol Microbiol 2014; 93:664-81. [PMID: 24962815 PMCID: PMC4127135 DOI: 10.1111/mmi.12682] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2014] [Indexed: 01/17/2023]
Abstract
Staphylococcus aureus has evolved as a pathogen that causes a range of diseases in humans. There are two dominant modes of evolution thought to explain most of the virulence differences between strains. First, virulence genes may be acquired from other organisms. Second, mutations may cause changes in the regulation and expression of genes. Here we describe an evolutionary event in which transposition of an IS element has a direct impact on virulence gene regulation resulting in hypervirulence. Whole-genome analysis of a methicillin-resistant S. aureus (MRSA) strain USA500 revealed acquisition of a transposable element (IS256) that is absent from close relatives of this strain. Of the multiple copies of IS256 found in the USA500 genome, one was inserted in the promoter sequence of repressor of toxins (Rot), a master transcriptional regulator responsible for the expression of virulence factors in S. aureus. We show that insertion into the rot promoter by IS256 results in the derepression of cytotoxin expression and increased virulence. Taken together, this work provides new insight into evolutionary strategies by which S. aureus is able to modify its virulence properties and demonstrates a novel mechanism by which horizontal gene transfer directly impacts virulence through altering toxin regulation.
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Affiliation(s)
- Meredith A. Benson
- Department of Microbiology, New York University School of Medicine, New York, New York, U.S.A
| | - Elizabeth A. Ohneck
- Department of Microbiology, New York University School of Medicine, New York, New York, U.S.A
| | - Chanelle Ryan
- Department of Medicine, Pediatric Infectious Disease Division, Columbia University, New York, New York, U.S.A
| | - Francis Alonzo
- Department of Microbiology, New York University School of Medicine, New York, New York, U.S.A
| | - Hannah Smith
- Department of Medicine, Pediatric Infectious Disease Division, Columbia University, New York, New York, U.S.A
| | - Apurva Narechania
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, NY, 10024, USA
| | | | - Sarah W. Satola
- Department of Medicine, Division of Infectious Diseases, Emory University, Atlanta, GA, U.S.A
- Atlanta Veterans Affairs Medical Center, Decatur, GA, U.S.A
| | - Anne-Catrin Uhlemann
- Department of Medicine, Division of Infectious Diseases, Columbia University Medical Center, New York, NY, U.S.A
| | - Robert Sebra
- Genome Center, Mount Sinai Hospital, New York, New York, U.S.A
| | - Gintaras Deikus
- Genome Center, Mount Sinai Hospital, New York, New York, U.S.A
| | - Bo Shopsin
- Department of Microbiology, New York University School of Medicine, New York, New York, U.S.A
- Department of Medicine, Division of Infectious Diseases, New York University School of Medicine, New York, New York, U.S.A
| | - Paul J. Planet
- Department of Medicine, Pediatric Infectious Disease Division, Columbia University, New York, New York, U.S.A
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, NY, 10024, USA
| | - Victor J. Torres
- Department of Microbiology, New York University School of Medicine, New York, New York, U.S.A
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67
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Inhibition of exotoxin production by mobile genetic element SCCmec-encoded psm-mec RNA is conserved in staphylococcal species. PLoS One 2014; 9:e100260. [PMID: 24926994 PMCID: PMC4057442 DOI: 10.1371/journal.pone.0100260] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 05/23/2014] [Indexed: 11/19/2022] Open
Abstract
Staphylococcal species acquire antibiotic resistance by incorporating the mobile-genetic element SCCmec. We previously found that SCCmec-encoded psm-mec RNA suppresses exotoxin production as a regulatory RNA, and the psm-mec translation product increases biofilm formation in Staphylococcus aureus. Here, we examined whether the regulatory role of psm-mec on host bacterial virulence properties is conserved among other staphylococcal species, S. epidermidis and S. haemolyticus, both of which are important causes of nosocomial infections. In S. epidermidis, introduction of psm-mec decreased the production of cytolytic toxins called phenol-soluble modulins (PSMs) and increased biofilm formation. Introduction of psm-mec with a stop-codon mutation that did not express PSM-mec protein but did express psm-mec RNA also decreased PSM production, but did not increase biofilm formation. Thus, the psm-mec RNA inhibits PSM production, whereas the PSM-mec protein increases biofilm formation in S. epidermidis. In S. haemolyticus, introduction of psm-mec decreased PSM production, but did not affect biofilm formation. The mutated psm-mec with a stop-codon also caused the same effect. Thus, the psm-mec RNA also inhibits PSM production in S. haemolyticus. These findings suggest that the inhibitory role of psm-mec RNA on exotoxin production is conserved among staphylococcal species, although the stimulating effect of the psm-mec gene on biofilm formation is not conserved.
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68
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Novel aspects of RNA regulation inStaphylococcus aureus. FEBS Lett 2014; 588:2523-9. [DOI: 10.1016/j.febslet.2014.05.037] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 05/16/2014] [Accepted: 05/19/2014] [Indexed: 11/24/2022]
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69
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The psmα locus regulates production of Staphylococcus aureus alpha-toxin during infection. Infect Immun 2014; 82:3350-8. [PMID: 24866799 DOI: 10.1128/iai.00089-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Staphylococcus aureus is a leading cause of human bacterial infection, causing a wide spectrum of disease ranging from skin and soft tissue infections to life-threatening pneumonia and sepsis. S. aureus toxins play an essential role in disease pathogenesis, contributing to both immunomodulation and host tissue injury. Prominent among these toxins are the membrane-active pore-forming cytolysin alpha-toxin (Hla) and the amphipathic α-helical phenol-soluble modulin (PSM) peptides. As deletion of either the hla or psm locus leads to a phenotypically similar virulence defect in skin and soft tissue infection, we sought to determine the relative contribution of each locus to disease pathogenesis. Here we show that production of Hla can be modulated by PSM expression. An S. aureus mutant lacking PSM expression exhibits a transcriptional delay in hla mRNA production and therefore fails to secrete normal levels of Hla at early phases of growth. This leads to attenuation of virulence in vitro and in murine skin and lung models of infection, correlating with reduced recovery of Hla from host tissues. Production of Hla and restoration of staphylococcal virulence can be achieved in the psm mutant by plasmid-driven overexpression of hla. Our study suggests the coordinated action of Hla and PSMs in host tissue during early pathogenesis, confirming a major role for Hla in epithelial injury during S. aureus infection. These findings highlight the possibility that therapeutics targeting PSM production may simultaneously prevent Hla-mediated tissue injury.
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70
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Omae Y, Sekimizu K, Kaito C. Identification of Staphylococcus aureus colony-spreading stimulatory factors from mammalian serum. PLoS One 2014; 9:e97670. [PMID: 24831518 PMCID: PMC4022729 DOI: 10.1371/journal.pone.0097670] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 04/09/2014] [Indexed: 11/19/2022] Open
Abstract
Staphylococcus aureus forms giant colonies on soft-agar surfaces, which is called colony-spreading. In the present study, we searched for host factors that influence S. aureus colony-spreading activity. The addition of calf serum, porcine serum, or silkworm hemolymph to soft-agar medium stimulated S. aureus colony-spreading activity. Gel filtration column chromatography of calf serum produced a high molecular weight fraction and a low molecular weight fraction, both of which exhibited colony-spreading stimulatory activity. In the low molecular weight fraction, we identified the stimulatory factor as bovine serum albumin. The stimulatory fraction in the high molecular weight fraction was identified as high-density lipoprotein (HDL) particles. Delipidation of HDL abolished the stimulatory activity of HDL. Phosphatidylcholine, which is the major lipid component in HDL particles, stimulated the colony-spreading activity. Other phosphatidylcholine-containing lipoprotein particles, low-density lipoprotein and very low-density lipoprotein, also showed colony-spreading stimulatory activity. These findings suggest that S. aureus colony-spreading activity is stimulated by albumin and lipoprotein particles in mammalian serum.
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Affiliation(s)
- Yosuke Omae
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan
| | - Kazuhisa Sekimizu
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan
| | - Chikara Kaito
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan
- * E-mail:
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71
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Genome-wide analysis of the regulatory function mediated by the small regulatory psm-mec RNA of methicillin-resistant Staphylococcus aureus. Int J Med Microbiol 2014; 304:637-44. [PMID: 24877726 DOI: 10.1016/j.ijmm.2014.04.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 04/15/2014] [Accepted: 04/21/2014] [Indexed: 01/12/2023] Open
Abstract
Several methicillin resistance (SCCmec) clusters characteristic of hospital-associated methicillin-resistant Staphylococcus aureus (MRSA) strains harbor the psm-mec locus. In addition to encoding the cytolysin, phenol-soluble modulin (PSM)-mec, this locus has been attributed gene regulatory functions. Here we employed genome-wide transcriptional profiling to define the regulatory function of the psm-mec locus. The immune evasion factor protein A emerged as the primary conserved and strongly regulated target of psm-mec, an effect we show is mediated by the psm-mec RNA. Furthermore, the psm-mec locus exerted regulatory effects that were more moderate in extent. For example, expression of PSM-mec limited expression of mecA, thereby decreasing methicillin resistance. Our study shows that the psm-mec locus has a rare dual regulatory RNA and encoded cytolysin function. Furthermore, our findings reveal a specific mechanism underscoring the recently emerging concept that S. aureus strains balance pronounced virulence and high expression of antibiotic resistance.
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72
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Aoyagi T, Kaito C, Sekimizu K, Omae Y, Saito Y, Mao H, Inomata S, Hatta M, Endo S, Kanamori H, Gu Y, Tokuda K, Yano H, Kitagawa M, Kaku M. Impact of psm-mec in the mobile genetic element on the clinical characteristics and outcome of SCCmec-II methicillin-resistant Staphylococcus aureus bacteraemia in Japan. Clin Microbiol Infect 2014; 20:912-9. [PMID: 24476401 DOI: 10.1111/1469-0691.12575] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/20/2014] [Accepted: 01/27/2014] [Indexed: 11/28/2022]
Abstract
Over-expression of alpha-phenol-soluble modulins (PSMs) results in high virulence of community-associated methicillin-resistant Staphylococcus aureus (MRSA). The psm-mec gene, located in the mobile genetic element SCCmec-II, suppresses PSMαs production. Fifty-two patients with MRSA bacteraemia were enrolled. MRSA isolates were evaluated with regard to the psm-mec gene sequence, bacterial virulence, and the minimum inhibitory concentration (MIC) of vancomycin and teicoplanin. Fifty-one MRSA isolates were classified as SCCmec-II, and 10 had one point mutation in the psm-mec promoter. We compared clinical characteristics and outcomes between mutant MRSA and wild-type MRSA. Production of PSMα3 in mutant MRSA was significantly increased, but biofilm formation was suppressed. Wild-type MRSA caused more catheter-related bloodstream infections (30/41 vs. 3/10, p 0.0028), whereas mutant MRSA formed more deep abscesses (4/10 vs. 3/41, p 0.035). Bacteraemia caused by mutant MRSA was associated with reduced 30-day mortality (1/10 vs. 13/41, p 0.25), although this difference was not significant. The MIC90 of teicoplanin was higher for wild-type MRSA (1.5 mg/L vs. 1 mg/L), but the MIC of vancomycin was not different between the two groups. The 30-day mortality of MRSA with a high MIC of teicoplanin (≥1.5 mg/L) was higher than that of strains with a lower MIC (≤0.75 mg/L) (6/10 vs. 6/33, p 0.017). Mutation of the psm-mec promoter contributes to virulence of SCCmec-II MRSA, and the product of psm-mec may determine the clinical characteristics of bacteraemia caused by SCCmec-II MRSA, but it does not affect mortality.
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Affiliation(s)
- T Aoyagi
- Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
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73
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Abstract
Small regulatory RNAs (sRNAs) that act by base-pairing were first discovered in so-called accessory DNA elements—plasmids, phages, and transposons—where they control replication, maintenance, and transposition. Since 2001, a huge body of work has been performed to predict and identify sRNAs in a multitude of bacterial genomes. The majority of chromosome-encoded sRNAs have been investigated in E. coli and other Gram-negative bacteria. However, during the past five years an increasing number of sRNAs were found in Gram-positive bacteria. Here, we outline our current knowledge on chromosome-encoded sRNAs from low-GC Gram-positive species that act by base-pairing, i.e., an antisense mechanism. We will focus on sRNAs with known targets and defined regulatory mechanisms with special emphasis on Bacillus subtilis.
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Affiliation(s)
- Sabine Brantl
- Friedrich-Schiller-Universität Jena; Biologisch-Pharmazeutische Fakultät; AG Bakteriengenetik; Philosophenweg 12; Jena, Germany
| | - Reinhold Brückner
- Mikrobiologie; TU Kaiserslautern; Paul-Ehrlich-Str. 23; D-67663 Kaiserslautern, Germany
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74
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Numata S, Nagata M, Mao H, Sekimizu K, Kaito C. CvfA protein and polynucleotide phosphorylase act in an opposing manner to regulate Staphylococcus aureus virulence. J Biol Chem 2014; 289:8420-31. [PMID: 24492613 DOI: 10.1074/jbc.m114.554329] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously identified CvfA (SA1129) as a Staphylococcus aureus virulence factor using a silkworm infection model. S. aureus cvfA-deleted mutants exhibit decreased expression of the agr locus encoding a positive regulator of hemolysin genes and decreased hemolysin production. CvfA protein hydrolyzes a 2',3'-cyclic phosphodiester bond at the RNA 3' terminus, producing RNA with a 3'-phosphate (3'-phosphorylated RNA, RNA with a 3'-phosphate). Here, we report that the cvfA-deleted mutant phenotype (decreased agr expression and hemolysin production) was suppressed by disrupting pnpA-encoding polynucleotide phosphorylase (PNPase) with 3'- to 5'-exonuclease activity. The suppression was blocked by introducing a pnpA-encoding PNPase with exonuclease activity but not by a pnpA-encoding mutant PNPase without exonuclease activity. Therefore, loss of PNPase exonuclease activity suppressed the cvfA-deleted mutant phenotype. Purified PNPase efficiently degraded RNA with 2',3'-cyclic phosphate at the 3' terminus (2',3'-cyclic RNA), but it inefficiently degraded 3'-phosphorylated RNA. These findings indicate that 3'-phosphorylated RNA production from 2',3'-cyclic RNA by CvfA prevents RNA degradation by PNPase and contributes to the expression of agr and hemolysin genes. We speculate that in the cvfA-deleted mutant, 2',3'-cyclic RNA is not converted to the 3'-phosphorylated form and is efficiently degraded by PNPase, resulting in the loss of RNA essential for expressing agr and hemolysin genes, whereas in the cvfA/pnpA double-disrupted mutant, 2',3'-cyclic RNA is not degraded by PNPase, leading to hemolysin production. These findings suggest that CvfA and PNPase competitively regulate RNA degradation essential for S. aureus virulence.
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Affiliation(s)
- Shunsuke Numata
- From the Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1, 7-chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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75
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Induction of virulence gene expression in Staphylococcus aureus by pulmonary surfactant. Infect Immun 2014; 82:1500-10. [PMID: 24452679 DOI: 10.1128/iai.01635-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We performed a genomewide analysis using a next-generation sequencer to investigate the effect of pulmonary surfactant on gene expression in Staphylococcus aureus, a clinically important opportunistic pathogen. RNA sequence (RNA-seq) analysis of bacterial transcripts at late log phase revealed 142 genes that were upregulated >2-fold following the addition of pulmonary surfactant to the culture medium. Among these genes, we confirmed by quantitative reverse transcription-PCR analysis that mRNA amounts for genes encoding ESAT-6 secretion system C (EssC), an unknown hypothetical protein (NWMN_0246; also called pulmonary surfactant-inducible factor A [PsiA] in this study), and hemolysin gamma subunit B (HlgB) were increased 3- to 10-fold by the surfactant treatment. Among the major constituents of pulmonary surfactant, i.e., phospholipids and palmitate, only palmitate, which is the most abundant fatty acid in the pulmonary surfactant and a known antibacterial substance, stimulated the expression of these three genes. Moreover, these genes were also induced by supplementing the culture with detergents. The induction of gene expression by surfactant or palmitate was not observed in a disruption mutant of the sigB gene, which encodes an alternative sigma factor involved in bacterial stress responses. Furthermore, each disruption mutant of the essC, psiA, and hlgB genes showed attenuation of both survival in the lung and host-killing ability in a murine pneumonia model. These findings suggest that S. aureus resists membrane stress caused by free fatty acids present in the pulmonary surfactant through the regulation of virulence gene expression, which contributes to its pathogenesis within the lungs of the host animal.
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76
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Cheung GYC, Joo HS, Chatterjee SS, Otto M. Phenol-soluble modulins--critical determinants of staphylococcal virulence. FEMS Microbiol Rev 2014; 38:698-719. [PMID: 24372362 DOI: 10.1111/1574-6976.12057] [Citation(s) in RCA: 237] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 12/05/2013] [Accepted: 12/19/2013] [Indexed: 10/25/2022] Open
Abstract
Phenol-soluble modulins (PSMs) are a recently discovered family of amphipathic, alpha-helical peptides that have multiple roles in staphylococcal pathogenesis and contribute to a large extent to the pathogenic success of virulent staphylococci, such as Staphylococcus aureus. PSMs may cause lysis of many human cell types including leukocytes and erythrocytes, stimulate inflammatory responses, and contribute to biofilm development. PSMs appear to have an original role in the commensal lifestyle of staphylococci, where they facilitate growth and spreading on epithelial surfaces. Aggressive, cytolytic PSMs seem to have evolved from that original role and are mainly expressed in highly virulent S. aureus. Here, we will review the biochemistry, genetics, and role of PSMs in the commensal and pathogenic lifestyles of staphylococci, discuss how diversification of PSMs defines the aggressiveness of staphylococcal species, and evaluate potential avenues to target PSMs for drug development against staphylococcal infections.
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Affiliation(s)
- Gordon Y C Cheung
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, MD, USA
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77
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The importance of regulatory RNAs in Staphylococcus aureus. INFECTION GENETICS AND EVOLUTION 2014; 21:616-26. [DOI: 10.1016/j.meegid.2013.11.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 11/12/2013] [Accepted: 11/13/2013] [Indexed: 12/14/2022]
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78
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Kaito C, Sekimizu K. Western Blotting for Staphylococcus aureus AgrA. Bio Protoc 2014. [DOI: 10.21769/bioprotoc.1071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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79
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Abstract
Staphylococcus aureus is a leading pathogen for animals and humans, not only being one of the most frequently isolated bacteria in hospital-associated infections but also causing diseases in the community. To coordinate the expression of its numerous virulence genes for growth and survival, S. aureus uses various signalling pathways that include two-component regulatory systems, transcription factors, and also around 250 regulatory RNAs. Biological roles have only been determined for a handful of these sRNAs, including cis, trans, and cis-trans acting RNAs, some internally encoding small, functional peptides and others possessing dual or multiple functions. Here we put forward an inventory of these fascinating sRNAs; the proteins involved in their activities; and those involved in stress response, metabolisms, and virulence.
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Affiliation(s)
- Julien Guillet
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
| | - Marc Hallier
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
| | - Brice Felden
- Rennes University, Inserm U835-UpresEA2311, Pharmaceutical Biochemistry, Rennes, France
- * E-mail:
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80
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Li S, Huang H, Rao X, Chen W, Wang Z, Hu X. Phenol-soluble modulins: novel virulence-associated peptides of staphylococci. Future Microbiol 2013; 9:203-16. [PMID: 24295365 DOI: 10.2217/fmb.13.153] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Phenol-soluble modulins (PSMs), a novel class of small peptides with an amphipathic α-helical structure and strong surfactant-like properties, are produced by most staphylococci, especially pathogenic Staphylococcus aureus and Staphylococcus epidermidis. PSMs can: induce the production of proinflammatory cytokines; recruit, activate and lyse neutrophils to help staphylococci evade immune damage; lyse erythrocytes and are associated with the hemolysis of staphylococcal disease; facilitate the structuring and detachment of staphylococcal biofilms and disseminate biofilm-associated infection; and kill competing microbes and act as weapons in interbacterial warfare. Therefore, PSMs are considered to be critical virulence-associated factors and to play important roles in the pathogenesis of staphylococci. This review summarizes the classification, structure, expression regulation and biological functions of PSMs. The possible means to prevent PSM-associated diseases are also outlined in order to emphasize the need to investigate PSMs as potential targets for drug and vaccine design against staphylococcal infections.
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Affiliation(s)
- Shu Li
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
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81
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Abstract
PSMs are a recently discovered family of short, amphipathic, α-helical peptides in staphylococci. Several PSMs are key virulence determinants, particularly in highly virulent Staphylococcus aureus strains. PSMα peptides of S. aureus facilitate neutrophil lysis after phagocytosis, and are key contributors to several infection types, including skin infection and bacteremia. Furthermore, all PSMs contribute to biofilm structuring and the dissemination of biofilm-associated infection. Cytolytic PSMs as produced by S. aureus appear to have evolved from original functions in the non-infectious lifestyle of staphylococci. The surfactant properties of PSMs, which they all share, are believed to facilitate growth on epithelial surfaces. The basic role of PSMs in staphylococcal physiology is underscored, for example, by their exceptionally strict and direct control by quorum-sensing and the presence of a dedicated secretion system. Targeting PSMs for anti-staphylococcal drug development may be a promising approach to overcome the problems associated with widespread antibiotic resistance in staphylococci.
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Affiliation(s)
- Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, The National Institutes of Health, Bethesda, MA, USA.
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82
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James EH, Edwards AM, Wigneshweraraj S. Transcriptional downregulation of agr expression in Staphylococcus aureus during growth in human serum can be overcome by constitutively active mutant forms of the sensor kinase AgrC. FEMS Microbiol Lett 2013; 349:153-62. [PMID: 24164684 PMCID: PMC4274972 DOI: 10.1111/1574-6968.12309] [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: 09/10/2013] [Revised: 10/11/2013] [Accepted: 10/17/2013] [Indexed: 01/05/2023] Open
Abstract
The temporal and cell density-dependent regulation of expression of virtually all the Staphylococcus aureus virulon is under the control of the agr (accessory gene regulatory) operon. The expression of the agr operon is subject to transcriptional regulation by the AgrA/C two-component response regulator/sensor kinase pair. During bacteraemia, a frequent syndrome caused by methicillin-resistant S. aureus (MRSA), the transcriptional downregulation of agr expression has been attributed to the sequestration of the quorum-signalling molecule auto-inducing peptide (AIP) by the human serum component apolipoprotein B as part of an innate immune response to infection. However, it is not known whether transcriptional downregulation of agr expression during growth in human serum is additionally subjected to regulation by transcription regulatory proteins that either directly or indirectly affect transcription from the agr operon promoters. Here, using chromosomal fluorescence reporters of agr expression in S. aureus, we show that the transcriptional downregulation of agr expression in human serum can be overcome using constitutive active mutant forms of AgrC. Therefore, it seems that the sequestration of the AIP is likely to be the only mechanism by which the host innate immune response limits agr expression at the transcriptional level to maintain the host-pathogen balance towards a noninvasive outcome.
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Affiliation(s)
- Ellen H James
- Faculty of Medicine, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
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83
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Abstract
Staphylococcus aureus is an important human pathogen and a leading cause of death worldwide. Phenol-soluble modulins (PSMs) have recently emerged as a novel toxin family defining the virulence potential of highly aggressive S. aureus isolates. PSMs have multiple roles in staphylococcal pathogenesis, causing lysis of red and white blood cells, stimulating inflammatory responses and contributing to biofilm development and the dissemination of biofilm-associated infections. Moreover, the pronounced capacity of PSMs to kill human neutrophils after phagocytosis might explain failures in the development of anti-staphylococcal vaccines. Here, we discuss recent progress made in our understanding of the biochemical and genetic properties of PSMs and their role in S. aureus pathogenesis, and suggest potential avenues to target PSMs for the development of anti-staphylococcal drugs.
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84
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Hiramatsu K, Ito T, Tsubakishita S, Sasaki T, Takeuchi F, Morimoto Y, Katayama Y, Matsuo M, Kuwahara-Arai K, Hishinuma T, Baba T. Genomic Basis for Methicillin Resistance in Staphylococcus aureus. Infect Chemother 2013; 45:117-36. [PMID: 24265961 PMCID: PMC3780952 DOI: 10.3947/ic.2013.45.2.117] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Indexed: 12/31/2022] Open
Abstract
Since the discovery of the first strain in 1961 in England, MRSA, the most notorious multidrug-resistant hospital pathogen, has spread all over the world. MRSA repeatedly turned down the challenges by number of chemotherapeutics, the fruits of modern organic chemistry. Now, we are in short of effective therapeutic agents against MRSA prevailing among immuno-compromised patients in the hospital. On top of this, we recently became aware of the rise of diverse clones of MRSA, some of which have increased pathogenic potential compared to the classical hospital-associated MRSA, and the others from veterinary sources. They increased rapidly in the community, and started menacing otherwise healthy individuals by causing unexpected acute infection. This review is intended to provide a whole picture of MRSA based on its genetic makeup as a versatile pathogen and our tenacious colonizer.
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Affiliation(s)
- Keiichi Hiramatsu
- Department of Bacteriology, Juntendo University, Tokyo, Japan
- Research Center for Infection Control Science, Juntendo University, Tokyo, Japan
| | - Teruyo Ito
- Department of Bacteriology, Juntendo University, Tokyo, Japan
| | - Sae Tsubakishita
- Department of Veterinary Science, Rakuno Gakuen University, Hokkaido, Japan
| | | | | | - Yuh Morimoto
- Department of Bacteriology, Juntendo University, Tokyo, Japan
- Research Center for Infection Control Science, Juntendo University, Tokyo, Japan
| | - Yuki Katayama
- Department of Bacteriology, Juntendo University, Tokyo, Japan
| | - Miki Matsuo
- Department of Bacteriology, Juntendo University, Tokyo, Japan
| | | | - Tomomi Hishinuma
- Department of Bacteriology, Juntendo University, Tokyo, Japan
- Research Center for Infection Control Science, Juntendo University, Tokyo, Japan
| | - Tadashi Baba
- Department of Bacteriology, Juntendo University, Tokyo, Japan
- Research Center for Infection Control Science, Juntendo University, Tokyo, Japan
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