The 3’ UTR ofvigRis required for virulence inStaphylococcus aureusand has expanded through STAR sequence repeat insertions

Abstract

ABSTRACTStaphylococcus aureusis an adaptable human pathogen causing life-threatening endocarditis and bacteraemia. Methicillin-resistantS. aureus(MRSA) is alarmingly common, and treatment is confined to last-line antibiotics. Vancomycin is the treatment of choice for MRSA bacteraemia and vancomycin treatment failure is often associated with vancomycin-intermediateS. aureusstrains termed VISA. The regulatory 3’ UTR ofvigRmRNA contributes to vancomycin tolerance in the clinical VISA isolate JKD6008 and upregulates the lytic transglycosylase IsaA. Using MS2-affinity purification coupled with RNA sequencing (MAPS), we find that thevigR3’ UTR also interacts with mRNAs involved in carbon metabolism, amino acid biogenesis, cell wall biogenesis, and virulence. ThevigR3’ UTR was found to repressdapE, a succinyl-diaminopimelate desuccinylase required for lysine and cell wall peptidoglycan synthesis, suggesting a broader role in controlling cell wall metabolism and vancomycin tolerance. Deletion of thevigR3’ UTR increased VISA virulence in a wax moth larvae model, and we find that anisaAmutant is completely attenuated in the larvae model. Sequence and structural analysis of thevigR3’ UTR indicates that the UTR has expanded through the acquisition ofStaphylococcus aureusrepeat insertions (STAR repeats) that partly contribute sequence for theisaAinteraction seed and may functionalise the 3’ UTR. Our findings reveal an extended regulatory network forvigR, uncovering a novel mechanism of regulation of cell wall metabolism and virulence in a clinicalS. aureusisolate.