Motion of variable-length MreB filaments at the bacterial cell membrane influences cell morphology

• Published in: Molecular biology of the cell 2013-08, Vol.24 (15), p.2340-2349
• Main Authors: Reimold, Christian, Defeu Soufo, Herve Joel, Dempwolff, Felix, Graumann, Peter L
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Bacillus subtilis - cytology; Bacillus subtilis - metabolism; Bacillus subtilis - ultrastructure; Bacterial Proteins - metabolism; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Escherichia coli - cytology; Escherichia coli - metabolism; Escherichia coli - ultrastructure; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Kinetics; Luminescent Proteins - metabolism; Protein Interaction Domains and Motifs; Protein Multimerization; Recombinant Fusion Proteins - metabolism; Red Fluorescent Protein; Time-Lapse Imaging
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.e12-10-0728

The maintenance of rod-cell shape in many bacteria depends on actin-like MreB proteins and several membrane proteins that interact with MreB. Using superresolution microscopy, we show that at 50-nm resolution, Bacillus subtilis MreB forms filamentous structures of length up to 3.4 μm underneath the cell membrane, which run at angles diverging up to 40° relative to the cell circumference. MreB from Escherichia coli forms at least 1.4-μm-long filaments. MreB filaments move along various tracks with a maximal speed of 85 nm/s, and the loss of ATPase activity leads to the formation of extended and static filaments. Suboptimal growth conditions lead to formation of patch-like structures rather than extended filaments. Coexpression of wild-type MreB with MreB mutated in the subunit interface leads to formation of shorter MreB filaments and a strong effect on cell shape, revealing a link between filament length and cell morphology. Thus MreB has an extended-filament architecture with the potential to position membrane proteins over long distances, whose localization in turn may affect the shape of the cell wall.