Self-association of MreC as a regulatory signal in bacterial cell wall elongation
Alexandre Martins, Carlos Contreras‐Martel, Manon Janet-Maitre, Mayara M. Miyachiro, Leandro F. Estrozi, Daniel Maragno Trindade, Caique Camargo Malospirito, Fernanda Rodrigues-Costa, Lionel Imbert, Viviana Job, Guy Schoehn, Ina Attrée, Andréa Dessen
Abstract
The elongasome, or Rod system, is a protein complex that controls cell wall formation in rod-shaped bacteria. MreC is a membrane-associated elongasome component that co-localizes with the cytoskeletal element MreB and regulates the activity of cell wall biosynthesis enzymes, in a process that may be dependent on MreC self-association. Here, we use electron cryo-microscopy and X-ray crystallography to determine the structure of a self-associated form of MreC from Pseudomonas aeruginosa in atomic detail. MreC monomers interact in head-to-tail fashion. Longitudinal and lateral interfaces are essential for oligomerization in vitro, and a phylogenetic analysis of proteobacterial MreC sequences indicates the prevalence of the identified interfaces. Our results are consistent with a model where MreC's ability to alternate between self-association and interaction with the cell wall biosynthesis machinery plays a key role in the regulation of elongasome activity.