Abstract

Filaments of all actin-like proteins known to date are assembled from pairs of protofilaments that are arranged in a parallel fashion, generating polarity. Here we show that the prokaryotic actin homologue MreB forms pairs of protofilaments that adopt an antiparallel arrangement in vitro and in vivo. We provide an atomic view of antiparallel protofilaments of Caulobacter MreB as apparent from crystal structures. We show that a protofilament doublet is essential for MreB's function in cell shape maintenance and demonstrate by in vivo site-specific cross-linking the antiparallel orientation of MreB protofilaments in E. coli. 3D cryo-EM shows that pairs of protofilaments of Caulobacter MreB tightly bind to membranes. Crystal structures of different nucleotide and polymerisation states of Caulobacter MreB reveal conserved conformational changes accompanying antiparallel filament formation. Finally, the antimicrobial agents A22/MP265 are shown to bind close to the bound nucleotide of MreB, presumably preventing nucleotide hydrolysis and destabilising double protofilaments.

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Author details

  1. Fusinita Van den Ent

    MRC - Laboratory of Molecular Biology, Cambridge, United Kingdom
    For correspondence
    fent@mrc-lmb.cam.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
  2. Thierry Izoré

    MRC - Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  3. Tanmay AM Bharat

    MRC - Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  4. Christopher M Johnson

    MRC - Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  5. Jan Löwe

    MRC - Laboratory of Molecular Biology, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Michael Laub, Massachusetts Institute of Technology, United States

Version history

  1. Received: February 25, 2014
  2. Accepted: May 2, 2014
  3. Accepted Manuscript published: May 2, 2014 (version 1)
  4. Version of Record published: June 10, 2014 (version 2)

Copyright

© 2014, Van den Ent et al.

This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.

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  1. Fusinita Van den Ent
  2. Thierry Izoré
  3. Tanmay AM Bharat
  4. Christopher M Johnson
  5. Jan Löwe
(2014)
Bacterial actin MreB forms antiparallel double filaments
eLife 3:e02634.
https://doi.org/10.7554/eLife.02634

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https://doi.org/10.7554/eLife.02634

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