The Role of MreB in Producing Rod-Shaped Bacterial Cells

Abstract

MreB, an actin homolog, is known to form short, membrane-associated filaments that move circumferentially in rod-shaped bacteria, in association with cell wall-synthesizing enzymes. Despite being essential for rod shape, the mechanism by which MreB filaments are able to organize themselves and move circumferentially is not known. In this thesis, I will show that MreB filaments are able to sense cell curvature and align along the dimension of greatest principal curvature. The first chapter of this thesis is an introduction where I will discuss bacterial cell shape and organization, providing an overview of the current state of knowledge in both fields, and the importance of studying them. In the second chapter, I will provide evidence for the curvature-sensing ability of MreB filaments, and show how it enables cells to both maintain rod shape from generation to generation, as well as create rod shape de novo in round cells. I will then provide a model for this curvature-sensing property: the intrinsic, high curvature of MreB filaments, coupled with hydrophobic residues on the filament that directly associate with membranes could allow these filaments to preferentially bind along the more curved of the two principal curvatures. In the last chapter, I will discuss the questions that remain to be answered in the field of MreB-associated cell wall synthesis, and point out future directions for the extension of my work.