期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 109, 期 24, 页码 9432-9437出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1120761109
关键词
bacterial cell division; bacterial cytoskeleton; GTP hydrolysis
资金
- National Institute of Health [DP2OD006466]
- National Science Foundation [EF-1038697, OCI-1053575, TG-MCB110056, TG-MCB100121]
- James S. McDonnell Foundation
- Stanford University School of Medicine Dean
- [NSF-DBI-0960480]
- Direct For Biological Sciences [960480] Funding Source: National Science Foundation
- Direct For Biological Sciences
- Emerging Frontiers [1038697] Funding Source: National Science Foundation
- Div Of Biological Infrastructure [960480] Funding Source: National Science Foundation
The bacterial cytoskeletal protein FtsZ is a GTPase that is thought to provide mechanical constriction force via an unidentified mechanism. Purified FtsZ polymerizes into filaments with varying structures in vitro: while GTP-bound FtsZ assembles into straight or gently curved filaments, GDP-bound FtsZ forms highly curved filaments, prompting the hypothesis that a difference in the inherent curvature of FtsZ filaments provides mechanical force. However, no nucleotide-dependent structural transition of FtsZ monomers has been observed to support this force generation model. Here, we present a series of all-atom molecular dynamics simulations probing the effects of nucleotide binding on the structure of an FtsZ dimer. We found that the FtsZ-dimer structure is dependent on nucleotide-binding state. While a GTP-bound FtsZ dimer retained a firm monomer-monomer contact, a GDP-bound FtsZ dimer lost some of the monomer-monomer association, leading to a hinge-opening event that resulted in a more bent dimer, while leaving each monomer structure largely unaffected. We constructed models of FtsZ filaments and found that a GDP-FtsZ filament is much more curved than a GTP-FtsZ filament, with the degree of curvature matching prior experimental data. FtsZ dynamics were used to estimate the amount of force an FtsZ filament could exert when hydrolysis occurs ( 2030 pN per monomer). This magnitude of force is sufficient to direct inward cell-wall growth during division, and to produce the observed degree of membrane pinching in liposomes. Taken together, our data provide molecular-scale insight on the origin of FtsZ-based constriction force, and the mechanism underlying prokaryotic cell division.
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