Structure-based mechanism for activation of the AAA+ GTPase McrB by the endonuclease McrC

Abstract

McrBC is a bacterial antiphage defense system that cleaves methylated DNA and is composed of the AAA+ GTPase motor McrB and the endonuclease McrC. Here, the authors present the cryo-EM structure of E. coli McrBC that reveals how McrC inserts a stalk-like structure into the pore of the ring-shaped McrB hexamer and discuss mechanistic implications.