Comprehension of Antimicrobial Peptides Modulation of the Type VI Secretion System inVibrio cholerae

Abstract

The Type VI secretion System (T6SS) is a versatile weapon used by bacteria for virulence, resistance to grazing and competition with other bacteria. We previously demonstrated that the role of the T6SS in interbacterial competition and in resistance to grazing is enhanced in Vibrio cholerae in the presence of subinhibitory concentrations of polymyxin B (PmB). In this study, we performed a global quantitative proteomic analysis by liquid chromatography coupled to mass spectrometry and a transcriptomic analysis by quantitative PCR of the T6SS known regulators in V. cholerae grown with and without PmB. The proteome of V. cholerae is greatly modified in the presence of PmB at subinhibitory concentrations with more than 39 % of the identified cellular proteins displaying a difference in their abundance, including T6SS-related proteins (Hcp, VasC, TsaB and ClpV). We identified a regulator whose abundance and expression are increased in the presence of PmB, vxrB, the response regulator of the two-component system VxrAB. In a vxrAB deficient mutant, the expression of hcp measured by quantitative PCR, although globally reduced, was not modified in the presence of PmB, confirming its role in hcp upregulation with PmB. The upregulation of the T6SS in the presence of PmB appears to be, at least in part, due to the two-component system VxrAB.