An onboard checking mechanism ensures effector delivery of the type VI secretion system in Vibrio cholerae.

ABSTRACT: The type VI secretion system (T6SS) is a lethal yet energetically costly weapon in gram-negative bacteria. Through contraction of a long sheath, the T6SS ejects a few copies of effectors accompanied by hundreds of structural carrier proteins per delivery. The few ejected effectors, however, dictate T6SS functions. It remains elusive how the T6SS ensures effector loading and avoids futile ejection. Here, by systemically mutating the active sites of 3 Vibrio cholerae effectors, TseL, VasX, and VgrG3, we show that the physical presence but not their activities is crucial for T6SS assembly. We constructed catalytic mutants of TseL and VgrG3 and truncated VasX mutants. These mutations abolished the killing of the effector-cognate immunity mutants. We determined that the VasX-mediated ant

SUBMITTER: Liang X 

PROVIDER: S-EPMC6859309 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature