RodZ modulates geometric localization of the bacterial actin MreB to regulate cell shape

Alexandre Colavin,Kerwyn Casey Huang,Handuo Shi

doi:10.1038/s41467-018-03633-x

Alexandre Colavin, Kerwyn Casey Huang + Show 1 more

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https://doi.org/10.1038/s41467-018-03633-x

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Abstract

In the rod-shaped bacterium Escherichia coli, the actin-like protein MreB localizes in a curvature-dependent manner and spatially coordinates cell-wall insertion to maintain cell shape, although the molecular mechanism by which cell width is regulated remains unknown. Here we demonstrate that the membrane protein RodZ regulates the biophysical properties of MreB and alters the spatial organization of E. coli cell-wall growth. The relative expression levels of MreB and RodZ change in a manner commensurate with variations in growth rate and cell width, and RodZ systematically alters the curvature-based localization of MreB and cell width in a concentration-dependent manner. We identify MreB mutants that alter the bending properties of MreB filaments in molecular dynamics simulations similar to RodZ binding, and show that these mutants rescue rod-like shape in the absence of RodZ alone or in combination with wild-type MreB. Thus, E. coli can control its shape and dimensions by differentially regulating RodZ and MreB to alter the patterning of cell-wall insertion, highlighting the rich regulatory landscape of cytoskeletal molecular biophysics.

Highlights

In the rod-shaped bacterium Escherichia coli, the actin-like protein MreB localizes in a curvature-dependent manner and spatially coordinates cell-wall insertion to maintain cell shape, the molecular mechanism by which cell width is regulated remains unknown
We establish that the spatial organization of MreB in E. coli changes systematically across phases of growth, suggesting that the biophysical properties of MreB filaments alter in a manner commensurate with the nutrient-regulated changes in growth rate
Since RodZ expression modulates MreB curvature enrichment, and since our simulations predicted that RodZ-binding alters MreB filament mechanics, we asked whether the ΔrodZ suppressor mutants we studied in vivo exhibit smaller bending angles than MreBWT, indicating straighter polymers

Summary

Introduction

In the rod-shaped bacterium Escherichia coli, the actin-like protein MreB localizes in a curvature-dependent manner and spatially coordinates cell-wall insertion to maintain cell shape, the molecular mechanism by which cell width is regulated remains unknown. We demonstrate that the membrane protein RodZ regulates the biophysical properties of MreB and alters the spatial organization of E. coli cell-wall growth. The relative expression levels of MreB and RodZ change in a manner commensurate with variations in growth rate and cell width, and RodZ systematically alters the curvature-based localization of MreB and cell width in a concentration-dependent manner. We study several MreB mutations that complement rod-like shape in the absence of RodZ when expressed alone or in combination with wild-type MreB (MreBWT) These mutants display enrichment of MreB to curvatures distinct from wild-type cells, and result in longer polymers. Our findings demonstrate that regulation of RodZ tunes the geometric localization of MreB and thereby alters cell shape

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