ToI Energy-Driven Localization of Pal and Anchoring to the Peptidoglycan Promote Outer-Membrane Constriction

During cell division, gram-negative bacteria must coordinate inner-membrane invagination, peptidoglycan synthesis and cleavage and outer-membrane (OM) constriction. The OM constriction remains largely enigmatic, and the nature of this process, passive or active, is under debate. The proton-motive force dependent Tol Pal system performs a network of interactions within these three compartments. Here we confirm that the trans-envelope Tol Pal complex accumulates at constriction site in Escherichia coli. We show that the inner-membrane complex composed of TolA, ToIQ and ToIR recruits the OM complex ToIB Pal to the septum, in an energy-dependent process. Pal recruitment then allows its binding to peptidoglycan and subsequently OM constriction. Our results provide evidence that the constriction of the OM is an energized process. (C) 2019 Published by Elsevier Ltd.