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Fait A, Silva SF, Abrahamsson JÅH, Ingmer H. Staphylococcus aureus response and adaptation to vancomycin. Adv Microb Physiol 2024; 85:201-258. [PMID: 39059821 DOI: 10.1016/bs.ampbs.2024.04.006] [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] [Indexed: 07/28/2024]
Abstract
Antibiotic resistance is an increasing challenge for the human pathogen Staphylococcus aureus. Methicillin-resistant S. aureus (MRSA) clones have spread globally, and a growing number display decreased susceptibility to vancomycin, the favoured antibiotic for treatment of MRSA infections. These vancomycin-intermediate S. aureus (VISA) or heterogeneous vancomycin-intermediate S. aureus (hVISA) strains arise from accumulation of a variety of point mutations, leading to cell wall thickening and reduced vancomycin binding to the cell wall building block, Lipid II, at the septum. They display only minor changes in vancomycin susceptibility, with varying tolerance between cells in a population, and therefore, they can be difficult to detect. In this review, we summarize current knowledge of VISA and hVISA. We discuss the role of genetic strain background or epistasis for VISA development and the possibility of strains being 'transient' VISA with gene expression changes mediated by, for example, VraTSR, GraXSR, or WalRK signal transduction systems, leading to temporary vancomycin tolerance. Additionally, we address collateral susceptibility to other antibiotics than vancomycin. Specifically, we estimate how mutations in rpoB, encoding the β-subunit of the RNA polymerase, affect overall protein structure and compare changes with rifampicin resistance. Ultimately, such in-depth analysis of VISA and hVISA strains in terms of genetic and transcriptional changes, as well as changes in protein structures, may pave the way for improved detection and guide antibiotic therapy by revealing strains at risk of VISA development. Such tools will be valuable for keeping vancomycin an asset also in the future.
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Affiliation(s)
- Anaëlle Fait
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark; Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Stephanie Fulaz Silva
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | - Hanne Ingmer
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark.
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Oliveira F, Gaio V, Brás S, Oliveira S, França A. Host Soluble Factors Cause Changes in Staphylococcus epidermidis Antibiotic Susceptibility and Biofilm Formation Ability. Pathogens 2023; 12:1064. [PMID: 37624024 PMCID: PMC10459130 DOI: 10.3390/pathogens12081064] [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: 07/08/2023] [Revised: 08/10/2023] [Accepted: 08/15/2023] [Indexed: 08/26/2023] Open
Abstract
Staphylococcus epidermidis is a major nosocomial pathogen with a remarkable ability to adhere to the surfaces of indwelling medical devices and form biofilms. Unlike other nosocomial pathogens, the interaction of S. epidermidis with host factors has not been the focus of substantial research. This study aimed to assess the alterations in the antibiotic susceptibility and biofilm formation ability of S. epidermidis in the presence of host serum factors. S. epidermidis strain RP62A was cultured in a laboratory culture medium with or without human serum/plasma, and changes in antibiotic susceptibility, biofilm formation, and gene expression were evaluated. The data obtained revealed that exposure to host serum factors increased the susceptibility of S. epidermidis to glycopeptide antibiotics and was also detrimental to biofilm formation. Gene expression analysis revealed downregulation of both dltA and fmtC genes shortly after human serum/plasma exposure. The importance of transferrin-mediated iron sequestration as a host anti-biofilm strategy against S. epidermidis was also emphasized. We have demonstrated that serum factors play a pivotal role as part of the host's anti-infective strategy against S. epidermidis infections, highlighting the importance of incorporating such factors during in vitro studies with this pathogen.
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Affiliation(s)
- Fernando Oliveira
- Centre of Biological Engineering, LIBRO—Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Vânia Gaio
- Centre of Biological Engineering, LIBRO—Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Susana Brás
- Centre of Biological Engineering, LIBRO—Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Sofia Oliveira
- Centre of Biological Engineering, LIBRO—Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Angela França
- Centre of Biological Engineering, LIBRO—Laboratory of Research in Biofilms Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
- LABBELS—Associate Laboratory, 4710-057 Guimarães/Braga, Portugal
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3
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Aguglia E, Chines E, Stefani S, Cafiso V. New Antimicrobial Resistance Strategies: An Adaptive Resistance Network Conferring Reduced Glycopeptide Susceptibility in VISA. Antibiotics (Basel) 2023; 12:antibiotics12040783. [PMID: 37107145 PMCID: PMC10135003 DOI: 10.3390/antibiotics12040783] [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: 03/07/2023] [Revised: 04/13/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
Background: Vancomycin-intermediate Staphylococcus aureus (VISA) emerges typically in the healthcare-associated methicillin-resistant S. aureus and more rarely in community-acquired S. aureus (CA-MRSA). VISA is a serious concern for public health due to its association with persistent infections, the failure of vancomycin treatment, and poor clinical outcomes. Currently, the burden of VISA is somewhat high, even though vancomycin is the mainstay treatment for severe MRSA infections. The molecular mechanisms of reduced glycopeptide susceptibility in S. aureus are constantly under investigation but have still not yet been fully characterized. Methods: Our goal was to investigate the reduced glycopeptide susceptibility mechanisms emerging in a VISA CA-MRSA versus its vancomycin-susceptible (VSSA) CA-MRSA parents in a hospitalized patient undergoing glycopeptide treatment. Comparative integrated omics, Illumina MiSeq whole-genome sequencing (WGS), RNA-Seq, and bioinformatics were performed. Results: Through a comparison of VISA CA-MRSA vs. its VSSA CA-MRSA parent, mutational and transcriptomic adaptations were found in a pool of genes involved, directly or indirectly, in the biosynthesis of the glycopeptide target conferring or supporting the VISA phenotype, and its cross-resistance with daptomycin. This pool included key genes responsible for the biosynthesis of the peptidoglycan precursors, i.e., D-Ala, the D-Ala-D-Ala dipeptide termini of the pentapeptide, and its incorporation in the nascent pentapeptide, as key targets of the glycopeptide resistance. Furthermore, accessory glycopeptide-target genes involved in the pathways corroborated the key adaptations, and thus, supported the acquisition of the VISA phenotype i.e., transporters, nucleotide metabolism genes, and transcriptional regulators. Finally, transcriptional changes were also found in computationally predicted cis-acting small antisense RNA triggering genes related both to the key or accessory adaptive pathways. Conclusion: Our investigation describes an adaptive resistance pathway acquired under antimicrobial therapy conferring reduced glycopeptide susceptibility in a VISA CA-MRSA due to a comprehensive network of mutational and transcriptional adaptations in genes involved in pathways responsible for the biosynthesis of glycopeptide's target or supporters of the key resistance path.
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Affiliation(s)
- Elvira Aguglia
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Eleonora Chines
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Viviana Cafiso
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
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Su M, Davis MH, Peterson J, Solis-Lemus C, Satola SW, Read TD. Effect of genetic background on the evolution of Vancomycin-Intermediate Staphylococcus aureus (VISA). PeerJ 2021; 9:e11764. [PMID: 34306830 PMCID: PMC8284308 DOI: 10.7717/peerj.11764] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 06/22/2021] [Indexed: 11/20/2022] Open
Abstract
Vancomycin-intermediate Staphylococcus aureus (VISA) typically arises through accumulation of chromosomal mutations that alter cell-wall thickness and global regulatory pathways. Genome-based prediction of VISA requires understanding whether strain background influences patterns of mutation that lead to resistance. We used an iterative method to experimentally evolve three important methicillin-resistant S. aureus (MRSA) strain backgrounds-(CC1, CC5 and CC8 (USA300)) to generate a library of 120 laboratory selected VISA isolates. At the endpoint, isolates had vancomycin MICs ranging from 4 to 10 μg/mL. We detected mutations in more than 150 genes, but only six genes (already known to be associated with VISA from prior studies) were mutated in all three background strains (walK, prs, rpoB, rpoC, vraS, yvqF). We found evidence of interactions between loci (e.g., vraS and yvqF mutants were significantly negatively correlated) and rpoB, rpoC, vraS and yvqF were more frequently mutated in one of the backgrounds. Increasing vancomycin resistance was correlated with lower maximal growth rates (a proxy for fitness) regardless of background. However, CC5 VISA isolates had higher MICs with fewer rounds of selection and had lower fitness costs than the CC8 VISA isolates. Using multivariable regression, we found that genes differed in their contribution to overall MIC depending on the background. Overall, these results demonstrated that VISA evolved through mutations in a similar set of loci in all backgrounds, but the effect of mutation in common genes differed with regard to fitness and contribution to resistance in different strains.
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Affiliation(s)
- Michelle Su
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Michelle H Davis
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Jessica Peterson
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Claudia Solis-Lemus
- Wisconsin Institute for Discovery and Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sarah W Satola
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Timothy D Read
- Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, Georgia, USA.,Department of Dermatology, School of Medicine, Emory University, Atlanta, Georgia, USA
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5
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Wang W, Sun B. VraCP regulates cell wall metabolism and antibiotic resistance in vancomycin-intermediate Staphylococcus aureus strain Mu50. J Antimicrob Chemother 2021; 76:1712-1723. [PMID: 33948657 PMCID: PMC8212773 DOI: 10.1093/jac/dkab113] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/13/2021] [Indexed: 01/29/2023] Open
Abstract
Objectives Vancomycin-intermediate Staphylococcus aureus (VISA) is increasingly being reported. Previous studies have shown that vraC and vraP may be involved in vancomycin resistance, although the molecular mechanism remains elusive. Methods The vraC (SAV0577), vraP (SAV0578) and vraCP mutants were constructed in Mu50 by allelic replacement. Some common VISA phenotypes were assessed in mutants, such as, susceptibility to the cell wall-associated antibiotics, cell wall thickness, autolysis activity and growth rate. RT-qPCR was performed to reveal the differential genes associated with these phenotypes. The binding abilities of VraC and VraCP to the promoters of target genes were determined by electrophoretic mobility shift assay (EMSA). Results VraP forms a stable complex with VraC to preserve their own stability. The vraC, vraP and vraCP mutants exhibited increased susceptibility to the cell wall-associated antibiotics and thinner cell walls compared with the WT strain. Consistent with these phenotypes, RT-qPCR revealed downregulated transcription of glyS, sgtB, ddl and alr2, which are involved in cell wall biosynthesis. Moreover, the transcription of cell wall hydrolysis genes, including sceD, lytM and isaA, was significantly downregulated, supporting the finding that mutants exhibited reduced autolysis rates. EMSA confirmed that both VraC and VraCP can directly bind to the sceD, lytM and isaA promoter regions containing the consensus sequence (5′-TTGTAAN2AN3TGTAA-3′), which is crucial for the binding of VraCP with target genes. GFP-reporter assays further revealed VraC and VraCP can enhance promoter activity of sceD to positively regulate its expression. Conclusions vraCP plays a significant role in cell wall metabolism and antibiotic resistance in Mu50.
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Affiliation(s)
- Wanying Wang
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People's Republic of China
| | - Baolin Sun
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People's Republic of China
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6
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Simcock PW, Bublitz M, Cipcigan F, Ryadnov MG, Crain J, Stansfeld PJ, Sansom MSP. Membrane Binding of Antimicrobial Peptides Is Modulated by Lipid Charge Modification. J Chem Theory Comput 2021; 17:1218-1228. [PMID: 33395285 DOI: 10.1021/acs.jctc.0c01025] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide interactions with lipid bilayers play a key role in a range of biological processes and depend on electrostatic interactions between charged amino acids and lipid headgroups. Antimicrobial peptides (AMPs) initiate the killing of bacteria by binding to and destabilizing their membranes. The multiple peptide resistance factor (MprF) provides a defense mechanism for bacteria against a broad range of AMPs. MprF reduces the negative charge of bacterial membranes through enzymatic conversion of the anionic lipid phosphatidyl glycerol (PG) to either zwitterionic alanyl-phosphatidyl glycerol (Ala-PG) or cationic lysyl-phosphatidyl glycerol (Lys-PG). The resulting change in the membrane charge is suggested to reduce the binding of AMPs to membranes, thus impeding downstream AMP activity. Using coarse-grained molecular dynamics to investigate the effects of these modified lipids on AMP binding to model membranes, we show that AMPs have substantially reduced affinity for model membranes containing Ala-PG or Lys-PG. More than 5000 simulations in total are used to define the relationship between lipid bilayer composition, peptide sequence (using five different membrane-active peptides), and peptide binding to membranes. The degree of interaction of a peptide with a membrane correlates with the membrane surface charge density. Free energy profile (potential of mean force) calculations reveal that the lipid modifications due to MprF alter the energy barrier to peptide helix penetration of the bilayer. These results will offer a guide to the design of novel peptides, which addresses the issue of resistance via MprF-mediated membrane modification.
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Affiliation(s)
- Patrick W Simcock
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
| | - Maike Bublitz
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
| | | | - Maxim G Ryadnov
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, U.K
| | - Jason Crain
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
- IBM Research UK, Hartree Centre, Daresbury WA4 4AD, U.K
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
- School of Life Sciences and Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
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7
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Thitiananpakorn K, Aiba Y, Tan XE, Watanabe S, Kiga K, Sato'o Y, Boonsiri T, Li FY, Sasahara T, Taki Y, Azam AH, Zhang Y, Cui L. Association of mprF mutations with cross-resistance to daptomycin and vancomycin in methicillin-resistant Staphylococcus aureus (MRSA). Sci Rep 2020; 10:16107. [PMID: 32999359 PMCID: PMC7527455 DOI: 10.1038/s41598-020-73108-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 08/24/2020] [Indexed: 12/11/2022] Open
Abstract
We first reported a phenomenon of cross-resistance to vancomycin (VCM) and daptomycin (DAP) in methicillin-resistant Staphylococcus aureus (MRSA) in 2006, but mechanisms underlying the cross-resistance remain incompletely understood. Here, we present a follow-up study aimed to investigate genetic determinants associated with the cross-resistance. Using 12 sets of paired DAP susceptible (DAPS) and DAP non-susceptible (DAPR) MRSA isolates from 12 patients who had DAP therapy, we (i) assessed susceptibility to DAP and VCM, (ii) compared whole-genome sequences, (iii) identified mutations associated with cross-resistance to DAP and VCM, and (iv) investigated the impact of altered gene expression and metabolic pathway relevant to the cross-resistance. We found that all 12 DAPR strains exhibiting cross-resistance to DAP and VCM carried mutations in mprF, while one DAPR strain with reduced susceptibility to only DAP carried a lacF mutation. On the other hand, among the 32 vancomycin-intermediate S. aureus (VISA) strains isolated from patients treated with VCM, five out of the 18 strains showing cross-resistance to DAP and VCM carried a mprF mutation, while 14 strains resistant to only VCM had no mprF mutation. Moreover, substitution of mprF in a DAPS strain with mutated mprF resulted in cross-resistance and vice versa. The elevated lysyl-phosphatidylglycerol (L-PG) production, increased positive bacterial surface charges and activated cell wall (CW) synthetic pathways were commonly found in both clinical isolates and laboratory-developed mutants that carry mprF mutations. We conclude that mprF mutation is responsible for the cross-resistance of MRSA to DAP and VCM, and treatment with DAP is more likely to select for mprF-mediated cross-resistance than is with VCM.
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Affiliation(s)
- Kanate Thitiananpakorn
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yoshifumi Aiba
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Xin-Ee Tan
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Shinya Watanabe
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Kotaro Kiga
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yusuke Sato'o
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Tanit Boonsiri
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Feng-Yu Li
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Teppei Sasahara
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yusuke Taki
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Aa Haeruman Azam
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Yuancheng Zhang
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan
| | - Longzhu Cui
- Division of Bacteriology, Department of Infection and Immunity, Faculty of Medicine, Jichi Medical University, 3311-1, Yakushiji, Shimotsuke-shi, Tochigi, 329-0498, Japan.
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Karatzas KAG, Lemmens-den Toom NA, Tassou CC, van Leeuwen W, van Belkum A. Molecular characterization of piezotolerant and stress-resistant mutants of Staphylococcus aureus. J Appl Microbiol 2020; 130:901-912. [PMID: 32871628 DOI: 10.1111/jam.14832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 07/08/2020] [Accepted: 08/04/2020] [Indexed: 11/29/2022]
Abstract
AIMS In the previous work, following a pressure treatment with wild-type Staphylococcus aureus, we obtained piezotolerant isolates showing altered phenotypic characteristics. This work focuses on understanding the genetic background of their altered phenotype. METHODS AND RESULTS AK23, a representative piezotolerant isolate was subjected to DNA microarrays, corroborated by PCR product sequencing and revealed 10-gene deletion. All other piezotolerant isolates possessed the mutation encompassing the region from SAR0665 to SAR0674 genes (9351 bp) which was most likely the result of recombination between two homologous loci (ATTGCGGGTG) present in both genes. RNA microarray transcriptomic analysis showed that due to partial deletion of the low-affinity phosphate transporter pitA, the high-affinity PhoU-PstABCS operon was upregulated in AK23 which could be the reason for piezotolerance. Furthermore, AK23 showed low levels of the virulence gene regulator rnaIII resulting in the downregulation of several agr system genes explaining the impaired virulence characteristics of the mutant. CONCLUSIONS Naturally occurring mutations can result in piezotolerance which can be of a concern for high hydrostatic pressure-treated foods. SIGNIFICANCE AND IMPACT OF THE STUDY A locus has been identified in piezotolerant S. aureus mutants providing insight into possible mechanisms associated with phenotypic characteristics of S. aureus. Further work should study each individual gene of the locus.
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Affiliation(s)
- K A G Karatzas
- Department of Food and Nutritional Sciences, University of Reading, Reading, UK
| | - N A Lemmens-den Toom
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, GD Rotterdam, The Netherlands
| | - C C Tassou
- Hellenic Agricultural Organisation 'DEMETER', Institute of Technology of Agricultural Products, Attikis, Greece
| | - W van Leeuwen
- Leiden Centre for Applied Bioscience, University of Applied Science Leiden, Leiden, The Netherlands
| | - A van Belkum
- BioMérieux, Open Innovation & Partnerships, La Balme Les Grottes, France
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9
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Shu H, Zhang W, Yun Y, Chen W, Zhong Q, Hu Y, Chen H, Chen W. Metabolomics study on revealing the inhibition and metabolic dysregulation in Pseudomonas fluorescens induced by 3-carene. Food Chem 2020; 329:127220. [PMID: 32516715 DOI: 10.1016/j.foodchem.2020.127220] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 05/25/2020] [Accepted: 05/31/2020] [Indexed: 11/16/2022]
Abstract
3-Carene is a monoterpenoid that has an effective inhibitory ability against Pseudomonas fluorescens (P. fluorescens) which can induce a range of food contamination problems. In this study, ultra-performance liquid chromatography-mass spectrometry (UPLC-MS)-based metabolomics was used to elucidate the antimicrobial mechanism of 3-carene in P. fluorescens. Multivariate analysis of the metabolite data revealed significant differences in the potential metabolite profiles between groups. The results of univariate analysis showed that significant changes in 42 metabolites were observed after treatment with 3-carene for 12 h when compared to the control group. Moreover, 3-carene treatment resulted in disturbances in many metabolic processes, including amino acid metabolism, pantothenate and coenzyme A (CoA) biosynthesis and the tricarboxylic acid (TCA) cycle. These results provide a new insight into the antimicrobial mechanisms of 3-carene in P. fluorescens and enhance our understanding of the antimicrobial mechanism from a metabolic perspective.
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Affiliation(s)
- Huizhen Shu
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Weimin Zhang
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Yonghuan Yun
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Weijun Chen
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China; Chunguang Agro-product Processing Institute, Wenchang 571333, China
| | - Qiuping Zhong
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Yueying Hu
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China
| | - Haiming Chen
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China; Huachuang Institute of Areca Research-Hainan, Haikou 570226, China.
| | - Wenxue Chen
- College of Food Sciences & Engineering, Hainan University, 58 People Road, Haikou 570228, PR China; Chunguang Agro-product Processing Institute, Wenchang 571333, China.
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10
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Tran NT, Huang X, Hong HJ, Bush MJ, Chandra G, Pinto D, Bibb MJ, Hutchings MI, Mascher T, Buttner MJ. Defining the regulon of genes controlled by σ E , a key regulator of the cell envelope stress response in Streptomyces coelicolor. Mol Microbiol 2019; 112:461-481. [PMID: 30907454 PMCID: PMC6767563 DOI: 10.1111/mmi.14250] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2019] [Indexed: 01/01/2023]
Abstract
The extracytoplasmic function (ECF) σ factor, σE , is a key regulator of the cell envelope stress response in Streptomyces coelicolor. Although its role in maintaining cell wall integrity has been known for over a decade, a comprehensive analysis of the genes under its control has not been undertaken. Here, using a combination of chromatin immunoprecipitation-sequencing (ChIP-seq), microarray transcriptional profiling and bioinformatic analysis, we attempt to define the σE regulon. Approximately half of the genes identified encode proteins implicated in cell envelope function. Seventeen novel targets were validated by S1 nuclease mapping or in vitro transcription, establishing a σE -binding consensus. Subsequently, we used bioinformatic analysis to look for conservation of the σE target promoters identified in S. coelicolor across 19 Streptomyces species. Key proteins under σE control across the genus include the actin homolog MreB, three penicillin-binding proteins, two L,D-transpeptidases, a LytR-CpsA-Psr-family protein predicted to be involved in cell wall teichoic acid deposition and a predicted MprF protein, which adds lysyl groups to phosphatidylglycerol to neutralize membrane surface charge. Taken together, these analyses provide biological insight into the σE -mediated cell envelope stress response in the genus Streptomyces.
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Affiliation(s)
- Ngat T Tran
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Xiaoluo Huang
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.,Department Biology I, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, Planegg-Martinsried, 82152, Germany
| | - Hee-Jeon Hong
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Matthew J Bush
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Daniela Pinto
- Department Biology I, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, Planegg-Martinsried, 82152, Germany
| | - Maureen J Bibb
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Matthew I Hutchings
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Thorsten Mascher
- Department Biology I, Ludwig-Maximilians-Universität München, Großhaderner Str. 2-4, Planegg-Martinsried, 82152, Germany
| | - Mark J Buttner
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
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Read N, Howlett R, Smith MCM. An operon encoding enzymes for synthesis of a putative extracellular carbohydrate attenuates acquired vancomycin resistance in Streptomyces coelicolor. MICROBIOLOGY-SGM 2019; 165:208-223. [PMID: 30632959 DOI: 10.1099/mic.0.000763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Actinomycete bacteria use polyprenol phosphate mannose as a lipid-linked sugar donor for extra-cytoplasmic glycosyl transferases that transfer mannose to cell envelope polymers, including glycoproteins and glycolipids. Strains of Streptomyces coelicolor with mutations in the gene ppm1, encoding polyprenol phosphate mannose synthase, and in pmt, encoding a protein O-mannosyltransferase, are resistant to phage ϕC31 and have greatly increased susceptibility to some antibiotics, including vancomycin. In this work, second-site suppressors of the vancomycin susceptibility were isolated. The suppressor strains fell into two groups. Group 1 strains had increased resistance to vancomycin, teicoplanin and β-lactams, and had mutations in the two-component sensor regulator system encoded by vanSR, leading to upegulation of the vanSRJKHAX cluster. Group 2 strains only had increased resistance to vancomycin and these mostly had mutations in sco2592 or sco2593, genes that are derepressed in the presence of phosphate and are likely to be required for the synthesis of a phosphate-containing extracellular polymer. In some suppressor strains the increased resistance was only observed in media with limited phosphate (mimicking the phenotype of wild-type S. coelicolor), but two strains, DT3017_R21 (ppm1-vanR-) and DT3017_R15 (ppm1- sco2593-), retained resistance on media with high phosphate content. These results support the view that vancomycin resistance in S. coelicolor is a trade-off between mechanisms that confer resistance and at least one that interferes with resistance mediated through the sco2594-sco2593-sco2592 operon.
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12
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Roch M, Gagetti P, Davis J, Ceriana P, Errecalde L, Corso A, Rosato AE. Daptomycin Resistance in Clinical MRSA Strains Is Associated with a High Biological Fitness Cost. Front Microbiol 2017; 8:2303. [PMID: 29259579 PMCID: PMC5723333 DOI: 10.3389/fmicb.2017.02303] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 11/08/2017] [Indexed: 01/24/2023] Open
Abstract
Daptomycin remains as one of the main treatment options for Methicillin-Resistant Staphylococcus aureus (MRSA). Sporadic resistance cases reported in patients treated with either daptomycin or glycopeptides are a growing concern. In a previous study, we described a clinical case of a patient with a community-acquired MRSA infection resistant to daptomycin and with intermediate resistance to vancomycin who developed a recurrent infection with a susceptible isogenic strain. In the present work, we further investigated the sequential events to determine whether the switch from a daptomycin resistance to a susceptible phenotype was due to a phenomenon of resistance reversion or recurrent infection with a susceptible strain. Pairwise competition experiments showed that the susceptible clinical recurrent SA6850 strain had increased fitness when compared to the resistant counterpart SA6820 strain. In fact, although we have demonstrated that reversion of daptomycin resistance to daptomycin susceptible can occur in vitro after serial passages in drug-free media, phylogenetic analysis suggested that the in vivo process was the result of a recurrent infection with a previous susceptible isolate carried by the patient rather than a resistance reversion of the strain. Whole genome sequence of evolved strains showed that daptomycin resistance in MRSA is associated with a high fitness cost mediated by mutations in mprF gene, revealed as a key element of the biological cost. Moreover, we determined that daptomycin resistance-associated fitness cost was independent of vancomycin intermediate resistance phenotype, as demonstrated in additional clinical MRSA vancomycin susceptible strains. This study highlights important observations as, despite daptomycin offers a useful treatment option for the patients with persistent infections, it has to be carefully monitored. The high fitness cost associated to daptomycin resistance may explain the reduced dissemination of daptomycin resistance and the absence of daptomycin reported outbreaks.
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Affiliation(s)
- Melanie Roch
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, United States
| | - Paula Gagetti
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, United States.,Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, Administración Nacional de Laboratorios e Institutos de Salud, Buenos Aires, Argentina
| | - James Davis
- Argonne National Laboratory (DOE), Lemont, IL, United States.,Computation Institute, University of Chicago, Chicago, IL, United States
| | - Paola Ceriana
- Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, Administración Nacional de Laboratorios e Institutos de Salud, Buenos Aires, Argentina
| | - Laura Errecalde
- Departamento de Microbiologia, Hospital General de Agudos Juan Fernandez, Buenos Aires, Argentina
| | - Alejandra Corso
- Servicio Antimicrobianos, Instituto Nacional de Enfermedades Infecciosas, Administración Nacional de Laboratorios e Institutos de Salud, Buenos Aires, Argentina
| | - Adriana E Rosato
- Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Diseases Research, Houston Methodist Research Institute, Houston, TX, United States
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13
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Plotkin BJ, Konakieva MI. Attenuation of antimicrobial activity by the human steroid hormones. Steroids 2017; 128:120-127. [PMID: 28951169 DOI: 10.1016/j.steroids.2017.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 08/28/2017] [Accepted: 09/20/2017] [Indexed: 11/16/2022]
Abstract
Upon entering the human host, Staphylococcus aureus is exposed to endogenous steroid hormones. The interaction between S. aureus and dehydroepiandosterone (DHEA) results in an increased resistance to the host cationic defense peptide, β-1 defensin, as well as vancomycin and other antibiotics that have a positive charge. The increased resistance to vancomycin is phenotypic and appears to correlate with a DHEA-mediated alteration in cell surface architecture. DHEA-mediated cell surface changes include alterations in: cell surface charge, surface hydrophobicity, capsule production, and carotenoid production. In addition, exposure to DHEA results in decreased resistance to lysis by Triton X-100 and lysozyme, indicating activation of murien hydrolase activity. We propose that DHEA is an interspecies quorum-like signal that triggers innate phenotypic host survival strategies in S. aureus that include increased carotenoid production and increased vancomycin resistance. Furthermore, this DHEA-mediated survival system may share the cholesterol-squalene pathway shown to be statin sensitive thus, providing a potential pathway for drug targeting.
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Affiliation(s)
- Balbina J Plotkin
- Department of Microbiology and Immunology, Midwestern University, Downers Grove, IL 60515, United States.
| | - Monika I Konakieva
- Department of Chemistry, American University, Washington, DC 20016, United States.
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14
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Fields RN, Roy H. Deciphering the tRNA-dependent lipid aminoacylation systems in bacteria: Novel components and structural advances. RNA Biol 2017; 15:480-491. [PMID: 28816600 PMCID: PMC6103681 DOI: 10.1080/15476286.2017.1356980] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
tRNA-dependent addition of amino acids to lipids on the outer surface of the bacterial membrane results in decreased effectiveness of antimicrobials such as cationic antimicrobial peptides (CAMPs) that target the membrane, and increased virulence of several pathogenic species. After a brief introduction to CAMPs and the various bacterial resistance mechanisms used to counteract these compounds, this review focuses on recent advances in tRNA-dependent pathways for lipid modification in bacteria. Phenotypes associated with amino acid lipid modifications and regulation of their expression will also be discussed.
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Affiliation(s)
- Rachel N Fields
- a Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando , Florida , United States of America
| | - Hervé Roy
- a Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando , Florida , United States of America
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15
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Slavetinsky C, Kuhn S, Peschel A. Bacterial aminoacyl phospholipids - Biosynthesis and role in basic cellular processes and pathogenicity. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:1310-1318. [PMID: 27940309 DOI: 10.1016/j.bbalip.2016.11.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Revised: 11/28/2016] [Accepted: 11/30/2016] [Indexed: 10/20/2022]
Abstract
The bacterial cell membrane accomplishes the controlled exchange of molecules with the extracellular space and mediates specific interactions with the environment. However, the cytoplasmic membrane also includes vulnerable targets for antimicrobial agents. A common feature of cationic antimicrobial peptides (CAMPs) produced by other bacteria or by the host immune system is to utilize the negative charge of bacterial phospholipids such as phosphatidylglycerol (PG) or cardiolipin (CL) for initial adherence and subsequent penetration into the membrane bilayer. To resist cationic antimicrobials many bacteria integrate positive charges into the membrane surface. This is accomplished by aminoacylation of negatively charged (PG) or (CL) with alanine, arginine, or lysine residues. The Multiple Peptide Resistance Factor (MprF) of Staphylococcus aureus is the prototype of a highly conserved protein family of aminoacyl phosphatidylglycerol synthases (aaPGSs) which modify PG or CL with amino acids. MprF is an oligomerizing membrane protein responsible for both, synthesis of lysyl phosphatidylglycerol (LysPG) in the inner leaflet of the cytoplasmic membrane and translocation of LysPG to the outer leaflet. This review focuses on occurrence, synthesis and function of bacterial aminoacyl phospholipids (aaPLs) and on the role of such lipids in basic cellular processes and pathogenicity. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
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Affiliation(s)
- Christoph Slavetinsky
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany
| | - Sebastian Kuhn
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany
| | - Andreas Peschel
- Interfaculty Institute of Microbiology and Infection Medicine, Infection Biology, University of Tübingen, 72076 Tübingen, Germany; German Centre for Infection Research (DZIF), Partner Site Tübingen, 72076 Tübingen, Germany.
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16
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Fozo EM, Rucks EA. The Making and Taking of Lipids: The Role of Bacterial Lipid Synthesis and the Harnessing of Host Lipids in Bacterial Pathogenesis. Adv Microb Physiol 2016; 69:51-155. [PMID: 27720012 DOI: 10.1016/bs.ampbs.2016.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In order to survive environmental stressors, including those induced by growth in the human host, bacterial pathogens will adjust their membrane physiology accordingly. These physiological changes also include the use of host-derived lipids to alter their own membranes and feed central metabolic pathways. Within the host, the pathogen is exposed to many stressful stimuli. A resulting adaptation is for pathogens to scavenge the host environment for readily available lipid sources. The pathogen takes advantage of these host-derived lipids to increase or decrease the rigidity of their own membranes, to provide themselves with valuable precursors to feed central metabolic pathways, or to impact host signalling and processes. Within, we review the diverse mechanisms that both extracellular and intracellular pathogens employ to alter their own membranes as well as their use of host-derived lipids in membrane synthesis and modification, in order to increase survival and perpetuate disease within the human host. Furthermore, we discuss how pathogen employed mechanistic utilization of host-derived lipids allows for their persistence, survival and potentiation of disease. A more thorough understanding of all of these mechanisms will have direct consequences for the development of new therapeutics, and specifically, therapeutics that target pathogens, while preserving normal flora.
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Affiliation(s)
- E M Fozo
- University of Tennessee, Knoxville, TN, United States.
| | - E A Rucks
- Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States.
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17
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Comparison of the Potency of the Lipid II Targeting Antimicrobials Nisin, Lacticin 3147 and Vancomycin Against Gram-Positive Bacteria. Probiotics Antimicrob Proteins 2016; 4:108-15. [PMID: 26781852 DOI: 10.1007/s12602-012-9095-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
While nisin (lantibiotic), lacticin 3147 (lantibiotic) and vancomycin (glycopeptides) are among the best studied lipid II-binding antimicrobials, their relative activities have never been compared. Nisin and lacticin 3147 have been employed/investigated primarily as food preservatives, although they do have potential in terms of veterinary and clinical applications. Vancomycin is used exclusively in clinical therapy. We reveal a higher potency for lacticin 3147 (MIC 0.95-3.8 μg/ml) and vancomycin (MIC 0.78-1.56 μg/ml) relative to that of nisin (MIC 6.28-25.14 μg/ml) against the food-borne pathogen Listeria monocytogenes. A comparison of the activity of the three antimicrobials against nisin resistance mutants of L. monocytogenes also reveals that their susceptibility to vancomycin and lacticin 3147 changed only slightly or not at all. A further assessment of relative activity against a selection of Bacillus cereus, Enterococcus and Staphylococcus aureus targets revealed that vancomycin MICs consistently ranged between 0.78 and 1.56 μg/ml against all but one strain. Lacticin 3147 was found to be more effective than nisin against B. cereus (lacticin 3147 MIC 1.9-3.8 μg/ml; nisin MIC 4.1-16.7 μg/ml) and E. faecium and E. faecalis targets (lacticin 3147 MIC from 1.9 to 3.8 μg/ml; nisin MIC ≥8.3 μg/ml). The greater effectiveness of lacticin 3147 is even more impressive when expressed as molar values. However, in agreement with the previous reports, nisin was the more effective of the two lantibiotics against S. aureus strains. This study highlights that in many instances the antimicrobial activity of these leading lantibiotics are comparable with that of vancomycin and emphasizes their particular value with respect to use in situations including foods and veterinary medicine, where the use of vancomycin is not permitted.
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18
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Gao W, Monk IR, Tobias NJ, Gladman SL, Seemann T, Stinear TP, Howden BP. Large tandem chromosome expansions facilitate niche adaptation during persistent infection with drug-resistant Staphylococcus aureus. Microb Genom 2015; 1:e000026. [PMID: 28348811 PMCID: PMC5320569 DOI: 10.1099/mgen.0.000026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 06/15/2015] [Indexed: 01/25/2023] Open
Abstract
We used genomics to study the evolution of meticillin-resistant Staphylococcus aureus (MRSA) during a complex, protracted clinical infection. Preparing closed MRSA genomes from days 0 and 115 allowed us to precisely reconstruct all genetic changes that occurred. Twenty-three MRSA blood cultures were also obtained during treatment, yielding 44 colony morphotypes that varied in size, haemolysis and antibiotic susceptibility. A subset of 15 isolates was sequenced and shown to harbour a total of 37 sequence polymorphisms. Eighty per cent of all mutations occurred from day 45 onwards, which coincided with the appearance of discrete chromosome expansions, and concluded in the day 115 isolate with a 98 kb tandem DNA duplication. In all heterogeneous vancomycin-intermediate Staphylococcus aureus isolates, the chromosomal amplification spanned at least a 20 kb region that notably included mprF, a gene involved in resistance to antimicrobial peptides, and parC, an essential DNA replication gene with an unusual V463 codon insertion. Restoration of the chromosome after serial passage under non-selective growth was accompanied by increased susceptibility to antimicrobial peptide killing and reduced vancomycin resistance, two signature phenotypes that help explain the clinical persistence of this strain. Elevated expression of the V463 parC was deleterious to the cell and reduced colony size, but did not alter ciprofloxacin susceptibility. In this study, we identified large DNA expansions as a clinically relevant mechanism of S. aureus resistance and persistence, demonstrating the extent to which bacterial chromosomes remodel in the face of antibiotic and host immune pressures.
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Affiliation(s)
- Wei Gao
- Microbiological Diagnostic Unit Public Health Laboratory, University of Melbourne, Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia
- Department of Microbiology and Immunology, University of Melbourne, Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia
| | - Ian R. Monk
- Department of Microbiology and Immunology, University of Melbourne, Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia
| | - Nicholas J. Tobias
- Department of Microbiology and Immunology, University of Melbourne, Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia
| | - Simon L. Gladman
- Victorian Life Sciences Computation Initiative, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Torsten Seemann
- Victorian Life Sciences Computation Initiative, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Timothy P. Stinear
- Department of Microbiology and Immunology, University of Melbourne, Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia
- Correspondence: Timothy P. Stinear ()
| | - Benjamin P. Howden
- Microbiological Diagnostic Unit Public Health Laboratory, University of Melbourne, Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia
- Department of Microbiology and Immunology, University of Melbourne, Doherty Institute for Infection and Immunity, Parkville, Victoria 3010, Australia
- Infectious Diseases Department, Austin Hospital, Heidelberg, Victoria 3084, Australia
- Benjamin P. Howden ()
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19
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Sohlenkamp C, Geiger O. Bacterial membrane lipids: diversity in structures and pathways. FEMS Microbiol Rev 2015; 40:133-59. [DOI: 10.1093/femsre/fuv008] [Citation(s) in RCA: 571] [Impact Index Per Article: 63.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2015] [Indexed: 12/22/2022] Open
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20
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Chang SC, Liu TP, Chen CJ, Lin LC, Lu JJ. Detection of heterogeneous vancomycin-intermediate Staphylococcus aureus isolates using a combination of δ-hemolysis assay and Etest. Diagn Microbiol Infect Dis 2014; 81:246-50. [PMID: 25600843 DOI: 10.1016/j.diagmicrobio.2014.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/16/2014] [Accepted: 12/21/2014] [Indexed: 12/23/2022]
Abstract
This study evaluated the δ-hemolysis assay for detection of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) isolates. The assay was performed using Columbia or trypticase soy blood agar plates without vancomycin at 37°C with 5% CO2, and the test isolate was streaked perpendicularly 1mm away from S. aureus RN4220. One hundred thirty-eight methicillin-resistant S. aureus (MRSA) bloodstream isolates with vancomycin MICs of 0.75-2 μg/mL were screened for hVISA by the δ-hemolysis assay and Etest glycopeptide resistance detection (GRD) method. The δ-hemolysis assay could be read at 24h and was more sensitive and specific than the Etest GRD at 24h and 48 h for detection of hVISA. Because most hVISA isolates have a vancomycin MIC of 2 μg/mL, we recommend screening MRSA isolates first using Etest for those with an MIC of 2 μg/mL and then performing the δ-hemolysis assay on these isolates for hVISA.
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Affiliation(s)
- Shih-Cheng Chang
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Tsui-Ping Liu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan
| | - Chih-Jung Chen
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Children's Hospital and Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Lee-Chung Lin
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan
| | - Jang-Jih Lu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan; Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
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21
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Kuhn S, Slavetinsky CJ, Peschel A. Synthesis and function of phospholipids in Staphylococcus aureus. Int J Med Microbiol 2014; 305:196-202. [PMID: 25595024 DOI: 10.1016/j.ijmm.2014.12.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Phospholipids are the major components of bacterial membranes, and changes in phospholipid composition affect important cellular processes such as metabolism, stress response, antimicrobial resistance, and virulence. The most prominent phospholipids in Staphylococcus aureus are phosphatidylglycerol, lysyl-phosphatidylglycerol, and cardiolipin, whose biosynthesis is mediated by a complex protein machinery. Phospholipid composition of the staphylococcal membrane has to be continuously adjusted to changing external conditions, which is achieved by a series of transcriptional and biochemical regulatory mechanisms. This mini-review outlines the current state of knowledge concerning synthesis, regulation, and function of the major staphylococcal phospholipids.
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Affiliation(s)
- Sebastian Kuhn
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology Division, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany
| | - Christoph J Slavetinsky
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology Division, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany
| | - Andreas Peschel
- University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology Division, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany.
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22
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Nawrocki KL, Crispell EK, McBride SM. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria. Antibiotics (Basel) 2014; 3:461-92. [PMID: 25419466 PMCID: PMC4239024 DOI: 10.3390/antibiotics3040461] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 09/25/2014] [Accepted: 09/28/2014] [Indexed: 01/09/2023] Open
Abstract
Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis.
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Affiliation(s)
- Kathryn L Nawrocki
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
| | - Emily K Crispell
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory University School of Medicine, 1510 Clifton Rd, Atlanta, GA 30322, USA; (K.L.N.); (E.K.C.)
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The msaABCR operon regulates resistance in vancomycin-intermediate Staphylococcus aureus strains. Antimicrob Agents Chemother 2014; 58:6685-95. [PMID: 25155591 DOI: 10.1128/aac.03280-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vancomycin-intermediate Staphylococcus aureus (VISA) strains present an increasingly difficult problem in terms of public health. However, the molecular mechanism for this resistance is not yet understood. In this study, we define the role of the msaABCR operon in vancomycin resistance in three clinical VISA strains, i.e., Mu50, HIP6297, and LIM2. Deletion of the msaABCR operon resulted in significant decreases in the vancomycin MIC (from 6.25 to 1.56 μg/ml) and significant reductions of cell wall thickness in strains Mu50 and HIP6297. Growth of the mutants in medium containing vancomycin at concentrations greater than 2 μg/ml resulted in decreases in the growth rate, compared with the wild-type strains. Mutation of the msaABCR operon also reduced the binding capacity for vancomycin. We conclude that the msaABCR operon contributes to resistance to vancomycin and cell wall synthesis in S. aureus.
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Alipiah NM, Shamsudin MN, Yusoff FM, Arshad A. Membrane Biosynthesis Gene Disruption in Methicillin-Resistant Staphylococcus aureus (MRSA) as Potential Mechanism for Reducing Antibiotic Resistance. Indian J Microbiol 2014. [DOI: 10.1007/s12088-014-0488-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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25
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Berscheid A, François P, Strittmatter A, Gottschalk G, Schrenzel J, Sass P, Bierbaum G. Generation of a vancomycin-intermediate Staphylococcus aureus (VISA) strain by two amino acid exchanges in VraS. J Antimicrob Chemother 2014; 69:3190-8. [PMID: 25103491 DOI: 10.1093/jac/dku297] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
OBJECTIVES Staphylococcus aureus is a notorious bacterial pathogen and antibiotic-resistant isolates complicate current treatment strategies. We characterized S. aureus VC40, a laboratory mutant that shows full resistance to glycopeptides (vancomycin and teicoplanin MICs ≥32 mg/L) and daptomycin (MIC = 4 mg/L), to gain deeper insights into the underlying resistance mechanisms. METHODS Genomics and transcriptomics were performed to characterize changes that might contribute to development of resistance. The mutations in vraS were reconstituted into a closely related parental background. In addition, antimicrobial susceptibility testing, growth analyses, transmission electron microscopy, lysostaphin-induced lysis and autolysis assays were performed to characterize the phenotype of resistant strains. RESULTS Genome sequencing of strain VC40 revealed 79 mutations in 75 gene loci including genes encoding the histidine kinases VraS and WalK that control cell envelope-related processes. Transcriptomics indicated the increased expression of their respective regulons. Although not reaching the measured MIC for VC40, reconstitution of the L114S and D242G exchanges in VraS(VC40) into the susceptible parental background (S. aureus NCTC 8325) resulted in increased resistance to glycopeptides and daptomycin. The expression of VraS(VC40) led to increased transcription of the cell wall stress stimulon, a thickened cell wall, a decreased growth rate, reduced autolytic activity and increased resistance to lysostaphin-induced lysis in the generated mutant. CONCLUSIONS We show that a double mutation of a single gene locus, namely vraS, is sufficient to convert the vancomycin-susceptible strain S. aureus NCTC 8325 into a vancomycin-intermediate S. aureus.
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Affiliation(s)
- Anne Berscheid
- Institute of Medical Microbiology, Immunology and Parasitology (IMMIP), University of Bonn, Bonn, Germany
| | - Patrice François
- Genomic Research Laboratory, Infectious Diseases Service, Geneva University Hospitals and the University of Geneva, Geneva, Switzerland
| | - Axel Strittmatter
- Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Gerhard Gottschalk
- Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Jacques Schrenzel
- Genomic Research Laboratory, Infectious Diseases Service, Geneva University Hospitals and the University of Geneva, Geneva, Switzerland
| | - Peter Sass
- Institute for Pharmaceutical Biology, University of Düsseldorf, Düsseldorf, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology and Parasitology (IMMIP), University of Bonn, Bonn, Germany
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Zecconi A, Scali F. Staphylococcus aureus virulence factors in evasion from innate immune defenses in human and animal diseases. Immunol Lett 2013; 150:12-22. [PMID: 23376548 DOI: 10.1016/j.imlet.2013.01.004] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/09/2012] [Accepted: 01/08/2013] [Indexed: 01/04/2023]
Abstract
In the last decades, Staphylococcus aureus acquired a dramatic relevance in human and veterinary medicine for different reasons, one of them represented by the increasing prevalence of antibiotic resistant strains. However, antibiotic resistance is not the only weapon in the arsenal of S. aureus. Indeed, these bacteria have plenty of virulence factors, including a vast ability to evade host immune defenses. The innate immune system represents the first line of defense against invading pathogens. This system consists of three major effector mechanisms: antimicrobial peptides and enzymes, the complement system and phagocytes. In this review, we focused on S. aureus virulence factors involved in the immune evasion in the first phases of infection: TLR recognition avoidance, adhesins affecting immune response and resistance to host defenses peptides and polypeptides. Studies of innate immune defenses and their role against S. aureus are important in human and veterinary medicine given the problems related to S. aureus antimicrobial resistance. Moreover, due to the pathogen ability to manipulate the immune response, these data are needed to develop efficacious vaccines or molecules against S. aureus.
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Affiliation(s)
- Alfonso Zecconi
- Università degli Studi di Milano, Dip. Scienze Veterinarie e Sanità Pubblica, Via Celoria 10, 20133 Milano, Italy.
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Bao Y, Sakinc T, Laverde D, Wobser D, Benachour A, Theilacker C, Hartke A, Huebner J. Role of mprF1 and mprF2 in the pathogenicity of Enterococcus faecalis. PLoS One 2012; 7:e38458. [PMID: 22723861 PMCID: PMC3377626 DOI: 10.1371/journal.pone.0038458] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 05/05/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Enterococcus faecalis is one of the leading causes of nosocomial infections. Due to its innate and acquired resistance to most antibiotics, identification of new targets for antimicrobial treatment of E. faecalis is a high priority. The multiple peptide resistance factor MprF, which was first described in Staphylococcus aureus, modifies phosphatidylglycerol with lysin and reduces the negative charge of the membrane, thus increasing resistance to cationic antimicrobial peptides. We studied the effect of mprF in E. faecalis regarding influence on bacterial physiology and virulence. RESULTS Two putative mprF paralogs (mprF1 and mprF2) were identified in E. faecalis by BLAST search using the well-described S. aureus gene as a lead. Two deletion mutants in E. faecalis 12030 were created by homologous recombination. Analysis of both mutants by thin-layer chromatography showed that inactivation of mprF2 abolishes the synthesis of three distinct amino-phosphatidylglycerols (PGs). In contrast, deletion of mprF1 did not interfere with the biosynthesis of amino-PG. Inactivation of mprF2 increased susceptibility against several antimicrobial peptides and resulted in a 42% increased biofilm formation compared to wild-type mprF. However, resistance to opsonic killing was increased in the mutant, while virulence in a mouse bacteremia model was unchanged. CONCLUSION Our data suggest that only mprF2 is involved in the aminoacylation of PG in enterococci, and is probably responsible for synthesis of Lys-PG, Ala-PG, and Arg-PG, while mprF1 does not seem to have a role in aminoacylation. As in other Gram-positive pathogens, aminoacylation through MprF2 increases resistance against cationic antimicrobial peptides. Unlike mprF found in other bacteria, mprF2 does not seem to be a major virulence factor in enterococci.
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Affiliation(s)
- Yinyin Bao
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
- EA4655 U2RM Stress/Virulence, Université de Caen Basse-Normandie, Caen, France
| | - Tuerkan Sakinc
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Diana Laverde
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Dominique Wobser
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Abdellah Benachour
- EA4655 U2RM Stress/Virulence, Université de Caen Basse-Normandie, Caen, France
| | - Christian Theilacker
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Axel Hartke
- EA4655 U2RM Stress/Virulence, Université de Caen Basse-Normandie, Caen, France
| | - Johannes Huebner
- Division of Infectious Diseases, Department of Medicine, University Hospital Freiburg, Freiburg, Germany
- * E-mail:
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Alanyl-phosphatidylglycerol and lysyl-phosphatidylglycerol are translocated by the same MprF flippases and have similar capacities to protect against the antibiotic daptomycin in Staphylococcus aureus. Antimicrob Agents Chemother 2012; 56:3492-7. [PMID: 22491694 DOI: 10.1128/aac.00370-12] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lysinylation of negatively charged phosphatidylglycerol by MprF proteins reduces the affinity of cationic antimicrobial peptides (CAMPs) for bacterial cytoplasmic membranes and reduces the susceptibility of several Gram-positive bacterial pathogens to CAMPs. MprF of Staphylococcus aureus encompasses a lysyl-phosphatidylglycerol (Lys-PG) synthase and a Lys-PG flippase domain. In contrast, Clostridium perfringens encodes two MprF homologs which specifically synthesize alanyl-phosphatidylglycerol (Ala-PG) or Lys-PG, while only the Lys-PG synthase is fused to a putative flippase domain. It remains unknown whether cationic Lys-PG and zwitterionic Ala-PG differ in their capacities to be translocated by MprF flippases and if both can reduce CAMP susceptibility in Gram-positive bacteria. By expressing the MprF proteins of C. perfringens in an S. aureus mprF deletion mutant, we found that both lipids can be efficiently produced in S. aureus. Simultaneous expression of the Lys-PG and Ala-PG synthases led to the production of both lipids and slightly increased the overall amounts of aminoacyl phospholipids. Ala-PG production by the corresponding C. perfringens enzyme did not affect susceptibility to CAMPs such as nisin and gallidermin or to the CAMP-like antibiotic daptomycin. However, coexpression of the Ala-PG synthase with flippase domains of Lys-PG synthesizing MprF proteins led to a wild-type level of daptomycin susceptibility, indicating that Ala-PG can also protect bacterial membranes against daptomycin and suggesting that Lys-PG flippases can also translocate the related lipid Ala-PG. Thus, bacterial aminoacyl phospholipid flippases exhibit more relaxed substrate specificity and Ala-PG and Lys-PG are more similar in their capacities to modulate membrane functions than anticipated.
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Dare K, Ibba M. Roles of tRNA in cell wall biosynthesis. WILEY INTERDISCIPLINARY REVIEWS. RNA 2012; 3:247-64. [PMID: 22262511 PMCID: PMC3873719 DOI: 10.1002/wrna.1108] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Recent research into various aspects of bacterial metabolism such as cell wall and antibiotic synthesis, degradation pathways, cellular stress, and amino acid biosynthesis has elucidated roles of aminoacyl-transfer ribonucleic acid (aa-tRNA) outside of translation. Although the two enzyme families responsible for cell wall modifications, aminoacyl-phosphatidylglycerol synthases (aaPGSs) and Fem, were discovered some time ago, they have recently become of intense interest for their roles in the antimicrobial resistance of pathogenic microorganisms. The addition of positively charged amino acids to phosphatidylglycerol (PG) by aaPGSs neutralizes the lipid bilayer making the bacteria less susceptible to positively charged antimicrobial agents. Fem transferases utilize aa-tRNA to form peptide bridges that link strands of peptidoglycan. These bridges vary among the bacterial species in which they are present and play a role in resistance to antibiotics that target the cell wall. Additionally, the formation of truncated peptides results in shorter peptide bridges and loss of branched linkages which makes bacteria more susceptible to antimicrobials. A greater understanding of the structure and substrate specificity of this diverse enzymatic family is necessary to aid current efforts in designing potential bactericidal agents. These two enzyme families are linked only by the substrate with which they modify the cell wall, aa-tRNA; their structure, cell wall modification processes and the physiological changes they impart on the bacterium differ greatly.
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Affiliation(s)
- Kiley Dare
- Department of Microbiology, Ohio State University, Columbus, OH, USA
| | - Michael Ibba
- Department of Microbiology, Ohio State University, Columbus, OH, USA
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Cafiso V, Bertuccio T, Spina D, Purrello S, Campanile F, Di Pietro C, Purrello M, Stefani S. Modulating activity of vancomycin and daptomycin on the expression of autolysis cell-wall turnover and membrane charge genes in hVISA and VISA strains. PLoS One 2012; 7:e29573. [PMID: 22253738 PMCID: PMC3253798 DOI: 10.1371/journal.pone.0029573] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 11/30/2011] [Indexed: 11/21/2022] Open
Abstract
Glycopeptides are still the gold standard to treat MRSA (Methicillin Resistant Staphylococcus aureus) infections, but their widespread use has led to vancomycin-reduced susceptibility [heterogeneous Vancomycin-Intermediate-Staphylococcus aureus (hVISA) and Vancomycin-Intermediate-Staphylococcus aureus (VISA)], in which different genetic loci (regulatory, autolytic, cell-wall turnover and cell-envelope positive charge genes) are involved. In addition, reduced susceptibility to vancomycin can influence the development of resistance to daptomycin. Although the phenotypic and molecular changes of hVISA/VISA have been the focus of different papers, the molecular mechanisms responsible for these different phenotypes and for the vancomycin and daptomycin cross-resistance are not clearly understood. The aim of our study was to investigate, by real time RT-PCR, the relative quantitative expression of genes involved in autolysis (atl-lytM), cell-wall turnover (sceD), membrane charges (mprF-dltA) and regulatory mechanisms (agr-locus-graRS-walKR), in hVISA and VISA cultured with or without vancomycin and daptomycin, in order to better understand the molecular basis of vancomycin-reduced susceptibility and the modulating activity of vancomycin and daptomycin on the expression of genes implicated in their reduced susceptibility mechanisms. Our results show that hVISA and VISA present common features that distinguish them from Vancomycin-Susceptible Staphylococcus aureus (VSSA), responsible for the intermediate glycopeptide resistance i.e. an increased cell-wall turnover, an increased positive cell-wall charge responsible for a repulsion mechanism towards vancomycin and daptomycin, and reduced agr-functionality. Indeed, VISA emerges from hVISA when VISA acquires a reduced autolysis caused by a down-regulation of autolysin genes, atl/lytM, and a reduction of the net negative cell-envelope charge via dltA over-expression. Vancomycin and daptomycin, acting in a similar manner in hVISA and VISA, can influence their cross-resistance mechanisms promoting VISA behavior in hVISA and enhancing the cell-wall pathways responsible for the intermediate vancomycin resistance in VISA. Daptomycin can also induce a charge repulsion mechanism both in hVISA and VISA increasing the activity of the mprF.
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Affiliation(s)
- Viviana Cafiso
- Unit of Microbiology, Department of Bio-Medical Sciences University of Catania, Catania, Italy
| | - Taschia Bertuccio
- Unit of Microbiology, Department of Bio-Medical Sciences University of Catania, Catania, Italy
| | - Daniela Spina
- Unit of Microbiology, Department of Bio-Medical Sciences University of Catania, Catania, Italy
| | - Simona Purrello
- Unit of Microbiology, Department of Bio-Medical Sciences University of Catania, Catania, Italy
| | - Floriana Campanile
- Unit of Microbiology, Department of Bio-Medical Sciences University of Catania, Catania, Italy
| | - Cinzia Di Pietro
- Unit of Genome and Molecular Complex Systems BioMedicine G Sichel, Department Gian Filippo Ingrassia, Catania, Italy
| | - Michele Purrello
- Unit of Genome and Molecular Complex Systems BioMedicine G Sichel, Department Gian Filippo Ingrassia, Catania, Italy
| | - Stefania Stefani
- Unit of Microbiology, Department of Bio-Medical Sciences University of Catania, Catania, Italy
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Mutation of RNA polymerase beta subunit (rpoB) promotes hVISA-to-VISA phenotypic conversion of strain Mu3. Antimicrob Agents Chemother 2011; 55:4188-95. [PMID: 21746940 DOI: 10.1128/aac.00398-11] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The clinical vancomycin-intermediate Staphylococcus aureus (VISA) strain Mu50 carries two mutations in the vraSR and graRS two-component regulatory systems (TCRSs), namely, vraS(I5N) and graR(N197S) (hereinafter designated graR). The clinical heterogeneously vancomycin-intermediate S. aureus (hVISA) strain Mu3 shares with Mu50 the mutation in vraS that encodes the VraS two-component histidine kinase. Previously, we showed that introduction of the plasmid pgraR, carrying the mutated two-component response regulator graR, converted the hVISA strain Mu3 into VISA (vancomycin MIC = 4 mg/liter). Subsequently, however, we found that the introduction of a single copy of graR into the Mu3 chromosome by a gene replacement method did not confer on Mu3 the VISA phenotype. The gene-replaced strain Mu3graR thus obtained remained hVISA (MIC ≤ 2 mg/liter), although a small increase in vancomycin MIC was observed compared to that of the parent strain Mu3. Reevaluation of the Mu3 and Mu50 genomes revealed the presence of another mutation responsible for the expression of the VISA phenotype in Mu50. Here, we demonstrate that in addition to the two regulator mutations, a third mutation found in the Mu50 rpoB gene, encoding the RNA polymerase β subunit, was required for Mu3 to achieve the level of vancomycin resistance of Mu50. The selection of strain Mu3graR with rifampin gave rise to rpoB mutants with various levels of increased vancomycin resistance. Furthermore, 3 (33%) of 10 independently isolated VISA strains established from the heterogeneous subpopulations of Mu3graR were found to possess rpoB mutations with or without an accompanying rifampin-resistance phenotype. The data indicate that a sizable proportion of the resistant hVISA cell subpopulations is composed of spontaneous rpoB mutants with various degrees of increased vancomycin resistance.
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Koprivnjak T, Peschel A. Bacterial resistance mechanisms against host defense peptides. Cell Mol Life Sci 2011; 68:2243-54. [PMID: 21560069 PMCID: PMC11115334 DOI: 10.1007/s00018-011-0716-4] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 04/26/2011] [Accepted: 04/26/2011] [Indexed: 12/30/2022]
Abstract
Host defense peptides and proteins are important components of the innate host defense against pathogenic microorganisms. They target negatively charged bacterial surfaces and disrupt microbial cytoplasmic membranes, which ultimately leads to bacterial destruction. Throughout evolution, pathogens devised several mechanisms to protect themselves from deleterious damage of host defense peptides. These strategies include (a) inactivation and cleavage of host defense peptides by production of host defense binding proteins and proteases, (b) repulsion of the peptides by alteration of pathogen's surface charge employing modifications by amino acids or amino sugars of anionic molecules (e.g., teichoic acids, lipid A and phospholipids), (c) alteration of bacterial membrane fluidity, and (d) expulsion of the peptides using multi drug pumps. Together with bacterial regulatory network(s) that regulate expression and activity of these mechanisms, they represent attractive targets for development of novel antibacterials.
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Affiliation(s)
- Tomaz Koprivnjak
- Department of Biotechnology, National Institute of Chemistry Slovenia, Hajdrihova 19, 1000, Ljubljana, Slovenia,
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Regulation of mprF by antisense RNA restores daptomycin susceptibility to daptomycin-resistant isolates of Staphylococcus aureus. Antimicrob Agents Chemother 2010; 55:364-7. [PMID: 20974866 DOI: 10.1128/aac.00429-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Mutations in mprF have been shown to result in reduced susceptibility to daptomycin and other cationic antibacterials. An mprF antisense-inducible plasmid was constructed and used to demonstrate that depletion of mprF can reestablish susceptibility to daptomycin. Inducing antisense to mprF also resulted in increased susceptibility to vancomycin and gentamicin but, paradoxically, decreased susceptibility to oxacillin. These results suggest that mprF mutations that reduce susceptibility to cationic antibacterials result in a gain-of-function phenotype.
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Domenech O, Dufrêne YF, Van Bambeke F, Tukens PM, Mingeot-Leclercq MP. Interactions of oritavancin, a new semi-synthetic lipoglycopeptide, with lipids extracted from Staphylococcus aureus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1876-85. [PMID: 20599683 DOI: 10.1016/j.bbamem.2010.06.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 05/25/2010] [Accepted: 06/11/2010] [Indexed: 12/01/2022]
Abstract
Oritavancin, a lipoglycopeptide with marked bactericidal activity against vancomycin-resistant Staphylococcus aureus and enterococci, induces calcein release from CL:POPE and POPG:POPE liposomes, an effect enhanced by an increase in POPG:POPE ratio, and decreased when replacing POPG by DPPG (Domenech et al., Biochim Biophys Acta 2009; 1788:1832-40). Using vesicles prepared from lipids extracted from S. aureus, we showed that oritavancin induces holes, erosion of the edges, and decrease of the thickness of the supported lipid bilayers (atomic force microscopy; AFM). Oritavancin also induced an increase of membrane permeability (calcein release) on a time- and dose-dependent manner. These effects were probably related to the ability of the drug to bind to lipid bilayers as shown by 8-anilino-1- naphthalene sulfonic acid (ANS) assay. Interaction of oritavancin with phospholipids at the level of their glycerol backbone and hydrophobic domain was studied by monitoring changes of Laurdan excitation generalized polarization (GP(ex)) and 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence anisotropy upon temperature increase. Oritavancin increased GP(ex) values and the transition temperature, indicating a more ordered structure at the level of the glycerol backbone. Oritavancin slightly decreased DPH fluorescence depolarization intensities, suggesting an increase in fluidity at the level of acyl chains. Together, our data confirm the interaction of oritavancin with lipids and the potential role of a rigidifying effect at the level of glycerol backbone for membrane permeabilization. This work shows how AFM and biophysical methods may help in characterizing drug-membrane interactions, and sheds further light on the mode of action of oritavancin.
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Affiliation(s)
- Oscar Domenech
- Université catholique de Louvain, Louvain Drug Research Institute, Unité de pharmacologie cellulaire et moléculaire, UCL 73.70, avenue E. Mounier 73, B-1200 Bruxelles, Belgium
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Reduced vancomycin susceptibility in Staphylococcus aureus, including vancomycin-intermediate and heterogeneous vancomycin-intermediate strains: resistance mechanisms, laboratory detection, and clinical implications. Clin Microbiol Rev 2010; 23:99-139. [PMID: 20065327 DOI: 10.1128/cmr.00042-09] [Citation(s) in RCA: 656] [Impact Index Per Article: 46.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The emergence of vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) over the past decade has provided a challenge to diagnostic microbiologists to detect these strains, clinicians treating patients with infections due to these strains, and researchers attempting to understand the resistance mechanisms. Recent data show that these strains have been detected globally and in many cases are associated with glycopeptide treatment failure; however, more rigorous clinical studies are required to clearly define the contribution of hVISA to glycopeptide treatment outcomes. It is now becoming clear that sequential point mutations in key global regulatory genes contribute to the hVISA and VISA phenotypes, which are associated predominately with cell wall thickening and restricted vancomycin access to its site of activity in the division septum; however, the phenotypic features of these strains can vary because the mutations leading to resistance can vary. Interestingly, changes in the staphylococcal surface and expression of agr are likely to impact host-pathogen interactions in hVISA and VISA infections. Given the subtleties of vancomycin susceptibility testing against S. aureus, it is imperative that diagnostic laboratories use well-standardized methods and have a framework for detecting reduced vancomycin susceptibility in S. aureus.
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Roy H. Tuning the properties of the bacterial membrane with aminoacylated phosphatidylglycerol. IUBMB Life 2009; 61:940-53. [PMID: 19787708 DOI: 10.1002/iub.240] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The bacterial envelope is a semi-permeable barrier that protects the cell from the hostilities of the environment. To survive the ever-changing conditions of their surroundings, bacteria need to rapidly adjust the biochemical properties of their cellular envelope. Amino acid (aa) addition to phosphatidylglycerol (PG) of the membrane is one of the mechanisms used by bacteria to lower the net negative charge of their cellular envelope, thereby decreasing its affinity for several antibacterial agents such as the cationic antimicrobial peptides (CAMPs) produced by the innate immune response during host infection. This process requires the activity of an integral membrane protein, called aa-PG synthase (aaPGS), to transfer the aa of aminoacyl-tRNA (aa-tRNA) onto the PG of the membrane. aaPGSs constitute a new family of virulence factors that are found in a wide range of microorganisms. aa-PGs not only provide resistance to CAMPs but also to other classes of antibacterial agents and to environmental stresses such as those encountered during extreme osmotic or acidic conditions. This review will describe the known biochemical properties of aa-PGSs, their specificity for aa-tRNAs and phospholipids, and the growing repertoire of aa used as substrates by these enzymes. Their prevalence in bacteria and the phenotypes and modulations of membrane properties associated with these molecules will be addressed, as well as their regulation as a component of the envelope stress response system in certain bacteria.
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Affiliation(s)
- Hervé Roy
- Department of Microbiology, Ohio State Biochemistry Program, Center for RNA Biology, The Ohio State University, Columbus, OH 43210-1292, USA.
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37
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Daptomycin: putative new mechanisms of action and resistance evolved from transcriptome data mining. ACTA ACUST UNITED AC 2009. [DOI: 10.1097/mrm.0b013e32832e82af] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Phenotypic and transcriptomic characterization of Bacillus subtilis mutants with grossly altered membrane composition. J Bacteriol 2008; 190:7797-807. [PMID: 18820022 DOI: 10.1128/jb.00720-08] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The Bacillus subtilis membrane contains diacylglycerol-based lipids with at least five distinct headgroups that together help to define the physical and chemical properties of the lipid bilayer. Here, we describe the phenotypic characterization of mutant strains lacking one or more of the following lipids: glycolipids (ugtP mutants), phosphatidylethanolamine (pssA and psd mutants), lysylphosphatidylglycerol (mprF), and cardiolipin (ywnE and ywjE). Alterations of membrane lipid headgroup composition are generally well-tolerated by the cell, and even severe alterations lead to only modest effects on growth proficiency. Mutants with decreased levels of positively charged lipids display an increased sensitivity to cationic antimicrobial compounds, and cells lacking glycolipids are more sensitive to the peptide antibiotic sublancin and are defective in swarming motility. A quadruple mutant strain (ugtP pssA mprF ywnE), with a membrane comprised predominantly of phosphatidylglycerol, is viable and grows at near-wild-type rates, although it forms long, coiled filaments. Transcriptome comparisons identified numerous regulons with altered expression in cells of the ugtP mutant, the pssA mprF ywnE triple mutant, and the ugtP pssA mprF ywnE quadruple mutant. These effects included a general decrease in expression of the SigD and FapR regulons and increased expression of cell envelope stress responses mediated by sigma(M) and the YvrGHb two-component system.
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Radek KA, Lopez-Garcia B, Hupe M, Niesman IR, Elias PM, Taupenot L, Mahata SK, O’Connor DT, Gallo RL. The neuroendocrine peptide catestatin is a cutaneous antimicrobial and induced in the skin after injury. J Invest Dermatol 2008; 128:1525-34. [PMID: 18185531 PMCID: PMC2757066 DOI: 10.1038/sj.jid.5701225] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Epithelia establish a microbial barrier against infection through the production of antimicrobial peptides (AMPs). In this study, we investigated whether catestatin (Cst), a peptide derived from the neuroendocrine protein chromogranin A (CHGA), is a functional AMP and is present in the epidermis. We show that Cst is antimicrobial against relevant skin microbes, including gram-positive and gram-negative bacteria, yeast, and fungi. The antimicrobial mechanism of Cst was found to be similar to other AMPs, as it was dependent on bacterial charge and growth conditions, and induced membrane disruption. The potential relevance of Cst against skin pathogens was supported by the observation that CHGA was expressed in keratinocytes. In human skin, CHGA was found to be proteolytically processed into the antimicrobial fragment Cst, thus enabling its AMP function. Furthermore, Cst expression in murine skin increased in response to injury and infection, providing potential for increased protection against infection. These data demonstrate that a neuroendocrine peptide has antimicrobial function against a wide assortment of skin pathogens and is upregulated upon injury, thus demonstrating a direct link between the neuroendocrine and cutaneous immune systems. JID JOURNAL CLUB ARTICLE: For questions, answers, and open discussion about this article please go to http://network.nature.com/group/jidclub.
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Affiliation(s)
- Katherine A. Radek
- Department of Dermatology, Veterans Affairs San Diego Healthcare System, San Diego, California, USA
- Department of Medicine, University of California at San Diego, La Jolla, California, USA
| | - Belen Lopez-Garcia
- Department of Dermatology, Veterans Affairs San Diego Healthcare System, San Diego, California, USA
- Department of Medicine, University of California at San Diego, La Jolla, California, USA
| | - Melanie Hupe
- Department of Dermatology, School of Medicine, University of California, San Francisco, California, USA
- Department of Dermatology, Veterans Administration Center, San Francisco, California, USA
| | - Ingrid R. Niesman
- Department of Dermatology, Veterans Affairs San Diego Healthcare System, San Diego, California, USA
| | - Peter M. Elias
- Department of Dermatology, School of Medicine, University of California, San Francisco, California, USA
- Department of Dermatology, Veterans Administration Center, San Francisco, California, USA
| | - Laurent Taupenot
- Department of Dermatology, Veterans Affairs San Diego Healthcare System, San Diego, California, USA
- Department of Medicine, University of California at San Diego, La Jolla, California, USA
| | - Sushil K. Mahata
- Department of Dermatology, Veterans Affairs San Diego Healthcare System, San Diego, California, USA
- Department of Medicine, University of California at San Diego, La Jolla, California, USA
| | - Daniel T. O’Connor
- Department of Dermatology, Veterans Affairs San Diego Healthcare System, San Diego, California, USA
- Department of Medicine, University of California at San Diego, La Jolla, California, USA
- Department of Medicine and Pharmacology, Center for Molecular Genetics, University of California at San Diego, La Jolla, California, USA
| | - Richard L. Gallo
- Department of Dermatology, Veterans Affairs San Diego Healthcare System, San Diego, California, USA
- Department of Medicine, University of California at San Diego, La Jolla, California, USA
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RajBhandary UL, Söll D. Aminoacyl-tRNAs, the bacterial cell envelope, and antibiotics. Proc Natl Acad Sci U S A 2008; 105:5285-6. [PMID: 18385375 PMCID: PMC2291102 DOI: 10.1073/pnas.0801193105] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Uttam L RajBhandary
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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41
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Mutated response regulator graR is responsible for phenotypic conversion of Staphylococcus aureus from heterogeneous vancomycin-intermediate resistance to vancomycin-intermediate resistance. Antimicrob Agents Chemother 2007; 52:45-53. [PMID: 17954695 DOI: 10.1128/aac.00534-07] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multistep genetic alteration is required for methicillin-resistant Staphylococcus aureus (MRSA) to achieve the level of vancomycin resistance of vancomycin-intermediate S. aureus (VISA). In the progression of vancomycin resistance, strains with heterogeneous vancomycin resistance, designated hetero-VISA, are observed. In studying the whole-genome sequencing of the representative hetero-VISA strain Mu3 and comparing it with that of closely related MRSA strains Mu50 (VISA) and N315 (vancomycin-susceptible S. aureus [VSSA]), we identified a mutation in the response regulator of the graSR two-component regulatory system. Introduction of mutated graR, designated graR*, but not intact graR, designated graRn, could convert the hetero-VISA phenotype of Mu3 into a VISA phenotype which was comparable to that of Mu50. The same procedure did not appreciably increase the vancomycin resistance of VSSA strain N315, indicating that graR* expression was effective only in the physiological milieu of hetero-VISA cell to achieve a VISA phenotype. Interestingly, the overexpression of graR* increased the daptomycin MICs in both Mu3 and N315 and decreased the oxacillin MIC in N315.
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42
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McCallum N, Brassinga AKC, Sifri CD, Berger-Bächi B. Functional characterization of TcaA: minimal requirement for teicoplanin susceptibility and role in Caenorhabditis elegans virulence. Antimicrob Agents Chemother 2007; 51:3836-43. [PMID: 17709474 PMCID: PMC2151418 DOI: 10.1128/aac.00722-07] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The inactivation of TcaA contributes to intrinsic teicoplanin resistance in experimental and clinical isolates of glycopeptide-intermediate resistant Staphylococcus aureus. PhoA fusions confirmed that TcaA is a transmembrane protein with a short intracellular N-terminal domain containing a C-4 zinc finger binding motif, a single membrane-spanning domain, and a large extracellular C-terminal domain. The region conferring teicoplanin susceptibility was narrowed down to the transmembrane part and the first third of the extracellular domain of TcaA, suggesting that neither the C-4 zinc finger binding motif nor the C terminus contributed to teicoplanin susceptibility. TcaA belongs to the cell wall stress stimulon, which comprises a set of genes universally upregulated by cell wall damage. Induction of tcaA was shown to be fully dependent on the two-component regulatory system VraSR. A 66-bp region upstream of the transcriptional start site, which contained an inverted repeat partially covering the promoter box, was shown to be essential for VraSR-mediated induction by cell wall stress. Interestingly, the induction or overexpression of tcaA did not contribute further to teicoplanin susceptibility, suggesting that small amounts of TcaA, such as those present under normal uninduced conditions, were sufficient for TcaA-mediated teicoplanin susceptibility. The strong attenuation of tcaA deletion mutants in a Caenorhabditis elegans survival assay suggested that TcaA may, in addition to affecting glycopeptide susceptibility, also play a role in virulence.
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Affiliation(s)
- Nadine McCallum
- Institute of Medical Microbiology, University of Zurich, Gloriastr. 32, 8006 Zurich, Switzerland.
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43
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Pillai SK, Gold HS, Sakoulas G, Wennersten C, Moellering RC, Eliopoulos GM. Daptomycin nonsusceptibility in Staphylococcus aureus with reduced vancomycin susceptibility is independent of alterations in MprF. Antimicrob Agents Chemother 2007; 51:2223-5. [PMID: 17404001 PMCID: PMC1891363 DOI: 10.1128/aac.00202-07] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A previous study documented the presence of mutations in mprF that accompanied the loss of daptomycin susceptibility among Staphylococcus aureus isolates following exposure to the drug. An association between the development of glycopeptide-intermediate S. aureus and daptomycin nonsusceptibility has also been recently described. We report that among three clinical S. aureus isolates which developed vancomycin heteroresistance, as well as daptomycin nonsusceptibility despite a lack of exposure to this drug, there were no mutations resulting in amino acid substitutions in MprF.
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Affiliation(s)
- Satish K Pillai
- Department of Infectious Disease, Cleveland Clinic Foundation, Mailstop S32, Cleveland, OH 44195, USA.
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44
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McCallum N, Karauzum H, Getzmann R, Bischoff M, Majcherczyk P, Berger-Bächi B, Landmann R. In vivo survival of teicoplanin-resistant Staphylococcus aureus and fitness cost of teicoplanin resistance. Antimicrob Agents Chemother 2006; 50:2352-60. [PMID: 16801412 PMCID: PMC1489778 DOI: 10.1128/aac.00073-06] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycopeptide resistance, in a set of in vitro step-selected teicoplanin-resistant mutants derived from susceptible Staphylococcus aureus SA113, was associated with slower growth, thickening of the bacterial cell wall, increased N-acetylglucosamine incorporation, and decreased hemolysis. Differential transcriptome analysis showed that as resistance increased, some virulence-associated genes became downregulated. In a mouse tissue cage infection model, an inoculum of 10(4) CFU of strain SA113 rapidly produced a high-bacterial-load infection, which triggered MIP-2 release, leukocyte infiltration, and reduced leukocyte viability. In contrast, with the same inoculum of the isogenic glycopeptide-resistant derivative NM67, CFU initially decreased, resulting in the elimination of the mutant in three out of seven cages. In the four cages in which NM67 survived, it partially regained wild-type characteristics, including thinning of the cell wall, reduced N-acetylglucosamine uptake, and increased hemolysis; however, the survivors also became teicoplanin hypersusceptible. The elimination of the teicoplanin-resistant mutants and selection of teicoplanin-hypersusceptible survivors in the tissue cages indicated that glycopeptide resistance imposes a fitness burden on S. aureus and is selected against in vivo, with restoration of fitness incurring the price of resistance loss.
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Affiliation(s)
- N McCallum
- Institute of Medical Microbiology, University of Zürich, 8006 Zurich, Switzerland.
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45
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Friedman L, Alder JD, Silverman JA. Genetic changes that correlate with reduced susceptibility to daptomycin in Staphylococcus aureus. Antimicrob Agents Chemother 2006; 50:2137-45. [PMID: 16723576 PMCID: PMC1479123 DOI: 10.1128/aac.00039-06] [Citation(s) in RCA: 347] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Daptomycin is a lipopeptide antibiotic with potent activity against gram-positive bacteria. Complete-genome comparisons of laboratory-derived Staphylococcus aureus with decreased susceptibility to daptomycin and their susceptible parent were used to identify genes that contribute to reduced susceptibility to daptomycin. Selective pressure of growth in sublethal concentrations of daptomycin resulted in the accumulation of mutations over time correlating with incremental decreases in susceptibility. Single point mutations resulting in amino acid substitutions occurred in three distinct proteins: MprF, a lysylphosphatidylglycerol synthetase; YycG, a histidine kinase; and RpoB and RpoC, the beta and beta' subunits of RNA polymerase. Sequence analysis of mprF, yycF, yycG, rpoB, and rpoC in clinical isolates that showed treatment-emergent increases in daptomycin MICs revealed point mutations in mprF and a nucleotide insertion in yycG, suggesting a role for these genes in decreased susceptibility to daptomycin in the hospital setting.
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Affiliation(s)
- Lisa Friedman
- Cubist Pharmaceuticals, Inc., Lexington, MA 02421, USA.
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46
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Wootton M, Macgowan AP, Walsh TR. Expression of tcaA and mprF and glycopeptide resistance in clinical glycopeptide-intermediate Staphylococcus aureus (GISA) and heteroGISA strains. Biochim Biophys Acta Gen Subj 2005; 1726:326-7. [PMID: 16213099 DOI: 10.1016/j.bbagen.2005.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Revised: 08/24/2005] [Accepted: 09/02/2005] [Indexed: 11/16/2022]
Abstract
Two genes recently associated with glycopeptide intermediate resistance in Staphylococcus aureus (GISA) are mprF and tcaA, with inactivation causing shifts in vancomycin resistance. This study reveals that expression levels of both genes are similar in groups of clinical GISA, heteroGISA and glycopeptide susceptible strains, suggesting no association with clinical isolates.
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Affiliation(s)
- M Wootton
- Department of Pathology and Microbiology, Bristol Centre for Antimicrobial Research and Evaluation, Medical Sciences, University of Bristol, and North Bristol Healthcare Trust, Southmead Hospital, Bristol, UK.
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Fedtke I, Götz F, Peschel A. Bacterial evasion of innate host defenses--the Staphylococcus aureus lesson. Int J Med Microbiol 2005; 294:189-94. [PMID: 15493829 DOI: 10.1016/j.ijmm.2004.06.016] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Bacterial pathogens such as Staphylococcus aureus use highly efficient mechanisms to evade recognition and elimination by the innate immune system. S. aureus produces sophisticated anti-inflammatory molecules and it employs several mechanisms protecting the bacteria against host cationic antimicrobial molecules such as defensin-like peptides and bacteriolytic enzymes such as lysozyme. Cell wall teichoic acids and lipoteichoic acids, complex Gram-positive surface polymers, and modified membrane lipids such as lysylphosphatidylglycerol are crucial in defensin resistance and other important aspects of staphylococcal virulence such as nasal colonization and biofilm formation on biomaterials. Certain S. aureus genes conferring escape from innate host defenses are conserved in many human pathogens suggesting that the underlying mechanisms are of general significance in bacterial virulence.
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Affiliation(s)
- Iris Fedtke
- University of Tübingen, Cellular and Molecular Microbiology, Medical Microbiology and Hygiene Department, Elfriede-Aulhorn-Str 6, D-72076 Tübingen, Germany
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48
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Nishi H, Komatsuzawa H, Fujiwara T, McCallum N, Sugai M. Reduced content of lysyl-phosphatidylglycerol in the cytoplasmic membrane affects susceptibility to moenomycin, as well as vancomycin, gentamicin, and antimicrobial peptides, in Staphylococcus aureus. Antimicrob Agents Chemother 2005; 48:4800-7. [PMID: 15561859 PMCID: PMC529239 DOI: 10.1128/aac.48.12.4800-4807.2004] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An association between moenomycin resistance and vancomycin intermediate resistance in Staphylococcus aureus was demonstrated previously. Thus, to elucidate the mechanism of vancomycin intermediate resistance, we searched for factors contributing to moenomycin resistance. Random Tn551 insertional mutagenesis of methicillin-resistant S. aureus strain COL yielded three mutants with decreased susceptibilities to moenomycin. Correspondingly, these mutants also exhibited slightly decreased susceptibilities to vancomycin. Genetic analysis revealed that two of the mutants had Tn551 insertions in the fmtC (mprF) gene, which is associated with the synthesis of lysyl-phosphatidylglycerol. The third Tn551 insertion was located in the lysC gene, which is involved in the biosynthesis of lysine from aspartic acid. Consequently, mutations in both of these loci reduced the lysyl-phosphatidylglycerol content in the cell membrane, giving it a more negative net charge. The positively charged antibiotic gentamicin and cationic antimicrobial peptides such as beta-defensins and CAP18 were more effective against the mutants. The levels of moenomycin and vancomycin binding to intact cells was also greater in the mutants than in the wild type, while the binding affinity was not altered when cells boiled in sodium dodecyl sulfate were used, indicating that both agents had higher affinities for the negatively charged membranes of the mutants. Therefore, the membrane charge of S. aureus appears to influence the efficacies of moenomycin, vancomycin, and other cationic antimicrobial agents.
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Affiliation(s)
- Hiromi Nishi
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, Kasumi 1-2-3, Minami-ku, Hiroshima City, Hiroshima, Japan
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Staubitz P, Neumann H, Schneider T, Wiedemann I, Peschel A. MprF-mediated biosynthesis of lysylphosphatidylglycerol, an important determinant in staphylococcal defensin resistance. FEMS Microbiol Lett 2004; 231:67-71. [PMID: 14769468 DOI: 10.1016/s0378-1097(03)00921-2] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Revised: 12/02/2003] [Accepted: 12/03/2003] [Indexed: 11/16/2022] Open
Abstract
Frequently bacteria are exposed to membrane-damaging cationic antimicrobial molecules (CAMs) produced by the host's immune system (defensins, cathelicidins) or by competing microorganisms (bacteriocins). Staphylococcus aureus achieves CAM resistance by modifying anionic phosphatidylglycerol with positively charged L-lysine, resulting in repulsion of the peptides. Inactivation of the novel S. aureus gene, mprF, which is found in many bacterial pathogens, has resulted in the loss of lysylphosphatidylglycerol (L-PG), increased inactivation by CAM-containing neutrophils, and attenuated virulence. We demonstrate here that expression of mprF is sufficient to confer L-PG production in Escherichia coli, which indicates that MprF represents the L-PG synthase. L-PG biosynthesis was studied in vitro and found to be dependent on phosphatidylglycerol and lysyl-tRNA, two putative substrate molecules. Further addition of cadaverin, a competitive inhibitor of the lysyl-tRNA synthetases, or of RNase A abolished L-PG biosynthesis, thereby confirming the involvement of lysyl-tRNA. This study forms the basis for further detailed analyses of L-PG biosynthesis and its role in bacterial infections.
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Affiliation(s)
- Petra Staubitz
- Cellular and Molecular Microbiology, Medical Microbiology Department, University of Tübingen, Elfriede-Aulhorn-Str. 6, D-72076 Tübingen, Germany
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50
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Oku Y, Kurokawa K, Ichihashi N, Sekimizu K. Characterization of the Staphylococcus aureus mprF gene, involved in lysinylation of phosphatidylglycerol. MICROBIOLOGY-SGM 2004; 150:45-51. [PMID: 14702396 DOI: 10.1099/mic.0.26706-0] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Lysylphosphatidylglycerol (LPG) is a basic phospholipid in which L-lysine from lysyl-tRNA is transferred to phosphatidylglycerol (PG). This study examined whether the Staphylococcus aureus mprF gene encodes LPG synthetase. A crude membrane fraction prepared from wild-type S. aureus cells had LPG synthetase activity that depended on PG and lysyl-tRNA, whereas the membrane fraction from an mprF deletion mutant did not. When S. aureus MprF protein was trans-expressed in wild-type Escherichia coli cells, LPG synthesis was induced, whereas it was not observed in E. coli pgsA3 mutant cells in which the amount of PG is significantly reduced. In addition, LPG synthetase activity and a 93 kDa protein whose molecular size corresponded to that of MprF protein were co-induced in the crude membrane fraction prepared from E. coli cells expressing MprF protein. The Km values of the LPG synthetase activity for PG and for lysyl-tRNA were 56 microM and 6.9 microM, respectively, consistent with those of S. aureus membranes. These results suggest that the MprF protein is LPG synthetase.
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Affiliation(s)
- Yusuke Oku
- Laboratory of Developmental Biochemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1 7-Chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kenji Kurokawa
- Laboratory of Developmental Biochemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1 7-Chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Norikazu Ichihashi
- Laboratory of Developmental Biochemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1 7-Chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kazuhisa Sekimizu
- Laboratory of Developmental Biochemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1 7-Chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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