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Published April 22, 2011 | Version Supplemental Material + Accepted Version
Journal Article Open

Long helical filaments are not seen encircling cells in electron cryotomograms of rod-shaped bacteria

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Abstract

How rod-shaped bacteria form and maintain their shape is an important question in bacterial cell biology. Results from fluorescent light microscopy have led many to believe that the actin homolog MreB and a number of other proteins form long helical filaments along the inner membrane of the cell. Here we show using electron cryotomography of six different rod-shaped bacterial species, at macromolecular resolution, that no long (>80 nm) helical filaments exist near or along either surface of the inner membrane. We also use correlated cryo-fluorescent light microscopy (cryo-fLM) and electron cryo-tomography (ECT) to identify cytoplasmic bundles of MreB, showing that MreB filaments are detectable by ECT. In light of these results, the structure and function of MreB must be reconsidered: instead of acting as a large, rigid scaffold that localizes cell-wall synthetic machinery, moving MreB complexes may apply tension to growing peptidoglycan strands to ensure their orderly, linear insertion.

Additional Information

© 2011 Elsevier Inc. Received 4 March 2011; Available online 16 March 2011. We thank Drs. Jian Shi and Alasdair McDowall for support of the EM instrumentation. This work was supported by NIH grant R01 GM094800B to G.J.J. and the Gordon and Betty Moore Center for Integrative Study of Cell Regulation. Work done by M.S. was supported by NIH grant RO1 AI049294.

Attached Files

Accepted Version - nihms289169.pdf

Supplemental Material - mmc1.mov

Supplemental Material - mmc2.mov

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Additional details

Identifiers

PMCID
PMC3093302
Eprint ID
23778
Resolver ID
CaltechAUTHORS:20110524-100904457

Funding

NIH
R01 GM094800B
Gordon and Betty Moore Foundation
NIH
R01 AI049294

Dates

Created
2011-05-24
Created from EPrint's datestamp field
Updated
2021-11-09
Created from EPrint's last_modified field