LytM factors affect the recruitment of autolysins to the cell division site in Caulobacter crescentus

3 years ago

LytM factors affect the recruitment of autolysins to the cell division site in Caulobacter crescentus

Grant J. Jensen, Andrea Möll, Katharina Kremer, Aleksandra Zielińska, Martin Thanbichler, Adrian Izquierdo Martinez, Maria Billini, Ariane Briegel

Most bacteria possess a peptidoglycan cell wall that determines their morphology and provides mechanical robustness during osmotic challenges. The biosynthesis of this structure is achieved by a large set of synthetic and lytic enzymes with varying substrate specificities. Although the biochemical functions of these proteins are conserved and well-investigated, the precise roles of individual factors and the regulatory mechanisms coordinating their activities in time and space remain incompletely understood. Here, we comprehensively analyze the autolytic machinery of the alphaproteobacterial model organism Caulobacter crescentus, with a specific focus on LytM-like endopeptidases, soluble transglycosylases, and amidases. Our data reveal a high degree of redundancy within each protein family but also specialized functions for individual family members under stress conditions. In addition, we identify two lytic transglycosylases and an amidase as new divisome components that are recruited to midcell at distinct stages of the cell cycle. The midcell localization of these proteins is affected by two LytM factors with degenerate catalytic domains, DipM and LdpF, which may serve as regulatory hubs coordinating the activities of multiple autolytic enzymes during cell constriction and fission, respectively. These findings set the stage for in-depth studies of the molecular mechanisms that control peptidoglycan remodeling in C. crescentus. This article is protected by copyright. All rights reserved. Peptidoglycan biosynthesis is mediated by a variety of synthetic and lytic enzymes, whose roles and regulation remain incompletely understood. Here, we comprehensively analyze the autolytic machinery of the alphaproteobacterium Caulobacter crescentus. Our study pinpoints factors critical for viability under stress conditions and identifies three more divisome-associated lytic enzymes. Moreover, it reveals two LytM factors with degenerate catalytic domains as regulatory hubs coordinating the activities of multiple peptidoglycan hydrolases during cell constriction and fission, respectively.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1111/mmi.13775