Establishment and maintenance of rod shape by the bacterial actin homologue MreB

Abstract

Bacteria have evolved a wide range of morphologies. For the majority of bacteria, the peptidoglycan

(PG) cell wall denes their cell shape. Although many of the proteins responsible

for synthesizing the PG cell wall are known, the mechanisms of how they are spatiotemporally

regulated remains unknown. For the most part, these enzymes are hypothesized to

exist in a cell wall synthesis complex. The most likely candidate for organizing this cell wall

synthesis complex is the bacterial actin homologue MreB. The structure of MreB polymers

and how they organize cell wall synthesis have only recently begun to be evaluated.

In this work, I use a combination of novel functional

uorescent protein fusion to MreB at

mreB's native locus along with novel 2D and 3D cell shape analysis of

uorescence images.

Using these techniques I rst show that MreB has preferential membrane curvature localization

and discuss how this is related to rod shape maintenance. Next I explore how MreB is

necessary for rod shape establishment through the examination of growth and reversion of

cell wall decient E. coli. Finally, I explore the role of MreB polymers in how bacterial cells

determine their radius. This work shows the multiple functions MreB polymers play in the

organization of cell wall synthesis and brings new insights into how bacteria establish and

maintain their rod shape.