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Structure and constriction mechanism of the actomyosin ring

Nguyen, L. T. and Jensen, G. J. (2017) Structure and constriction mechanism of the actomyosin ring. Molecular Biology of the Cell, 28 (26). Art. No. M175. ISSN 1059-1524. https://resolver.caltech.edu/CaltechAUTHORS:20180321-152351149

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Abstract

Cytokinesis is orchestrated by a contractile actomyosin ring, but its structure and mechanism remain elusive. We visualized the 3D structure of the ring in frozen‐hydrated dividing yeast cells by electron cryotomography (ECT). Detailed arrangements of actin filaments within the ring and with respect to the membrane were seen for the first time, providing a crucial spatial constraint for the constriction mechanism of the ring. Using the ECT data and input from the current literature we then explored sixteen mechanistic models by coarse‐grained simulations at the 3D molecular details, revealing plausible mechanisms for preventing membrane distortion and protein aggregation. We found that, in the model that best fits experimental data, both bipolar and membrane‐attached unipolar myosins exist in the ring, reconciling two different views in the field regarding the myosin configuration. In this model, ring tension is generated primarily by interactions between bipolar myosins and actin, and transmitted to the membrane via unipolar myosins. This model recapitulates a broad distribution of distances from actin filaments to the membrane observed in our tomograms and separation of two different myosin isoforms into the outer and inner subdomains of the ring reported in a previous fluorescence microscopy study. Further, it rationalizes how bundles of actomyosin were able to separate from the membrane in fluorescence microscopy experiments of the same previous study.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1091/mbc.E17-10-0618DOIAbstracts
http://www.molbiolcell.org/content/28/26/3727PublisherAbstracts
ORCID:
AuthorORCID
Jensen, G. J.0000-0003-1556-4864
Additional Information:© 2017 American Society for Cell Biology. Free via Creative Commons 2 months after publication.
Issue or Number:26
Record Number:CaltechAUTHORS:20180321-152351149
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180321-152351149
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85408
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:26 Mar 2018 21:30
Last Modified:03 Oct 2019 19:30

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