VraT/YvqF is required for methicillin resistance and activation of the VraSR regulon in Staphylococcus aureus.
Staphylococcus aureus infections caused by strains that are resistant to all forms of penicillin, so-called methicillin-resistant S. aureus (MRSA) strains, have become common. One strategy to counter MRSA infections is to use compounds that resensitize MRSA to methicillin. S. aureus responds to diverse classes of cell wall-inhibitory antibiotics, like methicillin, using the two-component regulatory system VraSR (vra) to up- or downregulate a set of genes (the cell wall stimulon) that presumably facilitates resistance to these antibiotics. Accordingly, VraS and VraR mutations decrease resistance to methicillin, vancomycin, and daptomycin cell wall antimicrobials. vraS and vraR are encoded together on a transcript downstream of two other genes, which we call vraU and vraT (previously called yvqF). By producing nonpolar deletions in vraU and vraT in a USA300 MRSA clinical isolate, we demonstrate that vraT is essential for optimal expression of methicillin resistance in vitro, whereas vraU is not required for this phenotype. The deletion of vraT also improved the outcomes of oxacillin therapy in mouse models of lung and skin infection. Since vraT expressed in trans did not complement a vra operon deletion, we conclude that VraT does not inactivate the antimicrobial. Genome-wide transcriptional microarray experiments reveal that VraT facilitates resistance by playing a necessary regulatory role in the VraSR-mediated cell wall stimulon. Our data prove that VraTSR comprise a novel three-component regulatory system required to facilitate resistance to cell wall agents in S. aureus. We also provide the first in vivo proof of principle for using VraT as a sole target to resensitize MRSA to β-lactams.
Department of Pediatrics, University of Chicago, Chicago, Illinois, USA.
Susan
S
Boyle-Vavra
Shouhui
S
Yin
Dae Sun
DS
Jo
Christopher P
CP
Montgomery
Robert S
RS
Daum
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002473:Cell Wall / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005809:Genes, Regulator; D016680:Genome, Bacterial; D008297:Male; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance / Q000187:drug effects / Q000235:genetics*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D018085:Regulon; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C478170:VraR protein, Staphylococcus aureus; C478169:VraS protein, Staphylococcus aureus; D008712:Methicillin