title: The bacterial actin MreB rotates, and rotation depends on cell-wall assembly.
abstract: Bacterial cells possess multiple cytoskeletal proteins involved in a wide range of cellular processes. These cytoskeletal proteins are dynamic, but the driving forces and cellular functions of these dynamics remain poorly understood. Eukaryotic cytoskeletal dynamics are often driven by motor proteins, but in bacteria no motors that drive cytoskeletal motion have been identified to date. Here, we quantitatively study the dynamics of the Escherichia coli actin homolog MreB, which is essential for the maintenance of rod-like cell shape in bacteria. We find that MreB rotates around the long axis of the cell in a persistent manner. Whereas previous studies have suggested that MreB dynamics are driven by its own polymerization, we show that MreB rotation does not depend on its own polymerization but rather requires the assembly of the peptidoglycan cell wall. The cell-wall synthesis machinery thus either constitutes a novel type of extracellular motor that exerts force on cytoplasmic MreB, or is indirectly required for an as-yet-unidentified motor. Biophysical simulations suggest that one function of MreB rotation is to ensure a uniform distribution of new peptidoglycan insertion sites, a necessary condition to maintain rod shape during growth. These findings both broaden the view of cytoskeletal motors and deepen our understanding of the physical basis of bacterial morphogenesis.
authors: Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA. sven@princeton.edu
authors: Sven
authors: S
authors: van Teeffelen
authors: Siyuan
authors: S
authors: Wang
authors: Leon
authors: L
authors: Furchtgott
authors: Kerwyn Casey
authors: KC
authors: Huang
authors: Ned S
authors: NS
authors: Wingreen
authors: Joshua W
authors: JW
authors: Shaevitz
authors: Zemer
authors: Z
authors: Gitai
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000560:Amdinocillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002473:Cell Wall / Q000378:metabolism*; D003198:Computer Simulation; D047630:Depsipeptides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D007700:Kinetics; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010455:Peptides / Q000378:metabolism; D010457:Peptidoglycan / Q000378:metabolism; D012399:Rotation; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000199:Actins; D000900:Anti-Bacterial Agents; D047630:Depsipeptides; D029968:Escherichia coli Proteins; D008164:Luminescent Proteins; D010455:Peptides; D010457:Peptidoglycan; C041438:ramoplanin; C078473:MreB protein, E coli; D014640:Vancomycin; D000560:Amdinocillin