Structure of the fission yeast actomyosin ring during constriction
Abstract
Cell division in many eukaryotes is driven by a ring containing actin and myosin. While much is known about the main proteins involved, the precise arrangement of actin filaments within the contractile machinery, and how force is transmitted to the membrane, remains unclear. Here we use cryosectioning and cryofocused ion beam milling to gain access to cryopreserved actomyosin rings in Schizosaccharomyces pombe for direct 3D imaging by electron cryotomography. Our results show that straight, overlapping actin filaments, running nearly parallel to each other and to the membrane, form a loose bundle of ∼150 nm in diameter that "saddles" the inward-bending membrane at the leading edge of the division septum. The filaments do not make direct contact with the membrane. Our analysis of the actin filaments reveals the variability in filament number, nearest-neighbor distances between filaments within the bundle, their distance from the membrane, and angular distribution with respect to the membrane.
Additional Information
© 2018 National Academy of Sciences. Published under the PNAS license. Edited by Thomas D. Pollard, Yale University, New Haven, CT, and approved December 13, 2017 (received for review June 23, 2017). Published online before print January 18, 2018. We thank Catherine Oikonomou for revising the manuscript for clarity and Frances Allen for initial training and guidance in cryo-FIB milling. We would also like to thank the reviewers for all of their critical feedback during the refinement of the manuscript. M.M. is an Intermediate Fellow of the Wellcome Trust−Department of Biotechnology India Alliance (IA/I/14/1/501317). M.M. acknowledges the India Alliance and the Department of Atomic Energy/Tata Institute of Fundamental Research for funds. This work was supported in part by National Institutes of Heath Grants GM122588 and GM082545 (to G.J.J.). Author contributions: M.T.S., L.T.N., M.M., and G.J.J. designed research; M.T.S., L.T.N., and M.S.L. performed research; D.R.O. and S.A. contributed new reagents/analytic tools; M.T.S., L.T.N., M.M., and G.J.J. analyzed data; and M.T.S., L.T.N., M.M., and G.J.J. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1711218115/-/DCSupplemental.Attached Files
Published - E1455.full.pdf
Submitted - 194902.full.pdf
Supplemental Material - pnas.1711218115.sapp.pdf
Supplemental Material - pnas.1711218115.sm01.mov
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Supplemental Material - pnas.201711218SI.pdf
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Additional details
- PMCID
- PMC5816141
- Eprint ID
- 84419
- Resolver ID
- CaltechAUTHORS:20180119-110411055
- IA/I/14/1/501317
- Wellcome Trust−Department of Biotechnology India Alliance
- Department of Atomic Energy (India)
- Tata Institute of Fundamental Research
- GM122588
- NIH
- GM082545
- NIH
- Created
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2018-01-19Created from EPrint's datestamp field
- Updated
-
2022-03-18Created from EPrint's last_modified field