RavA-ViaA linksVibrio choleraeCpx- and Zra2- envelope stress to antibiotic response

Abstract

RavA-ViaA were reported to play a role in aminoglycoside sensitivity but the mechanisms remain elusive. Here, we performed competition and survival experiments to confirm that deletion of ravA-viaA increases tolerance of the Gram-negative pathogen Vibrio cholerae to low and high aminoglycoside concentrations, during aerobic growth. Using high throughput strategies in this species, we identify Cpx and Zra2 two-component systems as new partners of RavA-ViaA. We show that the aminoglycoside tolerance of delta ravvia requires the presence of these membrane stress sensing two-component systems. We propose that deletion of the RavA-ViaA function facilitates the response aminoglycosides because of a pre-activated state of Cpx and Zra2 membrane stress response systems. We also find an impact of these genes on polymyxin B sensitivity and vancomycin resistance, and we show that simultaneous inactivation of ravvia function together with envelope stress response systems leads to outer membrane permeabilization. Vancomycin is mostly used for Gram-positive because of its low efficiency for crossing the Gram-negative outer membrane. Targeting of the ravA-viaA operon for inactivation could be a future strategy to allow uptake of vancomycin into multidrug resistant Gram-negative bacteria.

The RavA-ViaA chaperone complex modulates bacterial persistence through its association with the fumarate reductase enzyme

“…This is partly due to the lack of a clearly observed phenotype upon the deletion of the respective genes. However, various experiments conducted by our group and others have suggested a possible role of this chaperone system in modulating E. coli ’s as well as other Gram-negative bacteria’s sensitivity toward antibiotics ( 7 , 13 , 24 , 25 ). In this regard, studies on the metabolic drivers of persistence in E. coli have implicated fumarate and Frd in increased persistence against antibiotics ( 18 ).…”

“…Furthermore, it was recently suggested that RavA-ViaA facilitate the uptake of aminoglycosides antibiotics across the inner membrane of E. coli under low-energy cellular states ( 24 ). In Vibrio cholerae , the deletion of ravAviaA was found to increase tolerance of the bacteria to aminoglycosides under aerobic conditions but this phenotype requires the presence of an envelope stress two-component system ( 25 ).…”