The cell shape proteins MreB and MreC control cell morphogenesis by positioning cell wall synthetic complexes.

MreB, the bacterial actin homologue, is thought to function in spatially co-ordinating cell morphogenesis in conjunction with MreC, a protein that wraps around the outside of the cell within the periplasmic space. In Caulobacter crescentus, MreC physically associates with penicillin-binding proteins (PBPs) which catalyse the insertion of intracellularly synthesized precursors into the peptidoglycan cell wall. Here we show that MreC is required for the spatial organization of components of the peptidoglycan-synthesizing holoenzyme in the periplasm and MreB directs the localization of a peptidoglycan precursor synthesis protein in the cytosol.

The cell-shape protein MreC interacts with extracytoplasmic proteins including cell wall assembly complexes in Caulobacter crescentus.

The bacterial actin homolog, MreB, forms helical cables within the cell that are required for maintenance of a rod shape. These helical structures are thought to be involved in the spatial organization of cell wall (peptidoglycan) synthesizing complexes of penicillin-binding proteins (PBPs). Here, we examined the role of the MreC cell shape protein in this process in Caulobacter crescentus.

MreB, the cell shape-determining bacterial actin homologue, co-ordinates cell wall morphogenesis in Caulobacter crescentus.

The bacterial actin homologue, MreB, is required for the maintenance of a rod-shaped cell and has been shown to form spirals that traverse along the longitudinal axis of Bacillus subtilis and Escherichia coli cells. The depletion of MreB in Caulobacter crescentus resulted in lemon-shaped cells that possessed defects in the integrity of the cell wall. MreB localization appeared as bands or spirals that encircled the cell along its entire length and switched to a mid-cell location at a time that coincided with the initiation of cell division.