Condensation of FtsZ filaments can drive bacterial cell division

Forces are important in biological systems for accomplishing key cell functions, such as motility, organelle transport, and cell division. Currently, known force generation mechanisms typically involve motor proteins. In bacterial cells, no known motor proteins are involved in cell division. Instead...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2009-01, Vol.106 (1), p.121-126
Main Authors: Lan, Ganhui, Daniels, Brian R, Dobrowsky, Terrence M, Wirtz, Denis, Sun, Sean X
Format: Article
Language:English
Subjects:
Bacteria
Bacterial Proteins - metabolism
Bacterial Proteins - physiology
Bacterial Proteins - ultrastructure
Biological Sciences
Biomechanical Phenomena
Cell Division
Cell growth
Cell walls
Computer applications
Computer Simulation
Condensation
Contractility
Cytoskeletal Proteins - metabolism
Cytoskeletal Proteins - physiology
Cytoskeletal Proteins - ultrastructure
Escherichia coli - cytology
Filaments
Fluorescence
Free energy
GTP
Guanosine Triphosphate - metabolism
Hydrolysis
Modeling
Models, Molecular
Monomers
Motility
Organelles
Polymers
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Summary:Forces are important in biological systems for accomplishing key cell functions, such as motility, organelle transport, and cell division. Currently, known force generation mechanisms typically involve motor proteins. In bacterial cells, no known motor proteins are involved in cell division. Instead, a division ring (Z-ring) consists of mostly FtsZ, FtsA, and ZipA is used to exerting a contractile force. The mechanism of force generation in bacterial cell division is unknown. Using computational modeling, we show that Z-ring formation results from the colocalization of FtsZ and FtsA mediated by the favorable alignment of FtsZ polymers. The model predicts that the Z-ring undergoes a condensation transition from a low-density state to a high-density state and generates a sufficient contractile force to achieve division. FtsZ GTP hydrolysis facilitates monomer turnover during the condensation transition, but does not directly generate forces. In vivo fluorescence measurements show that FtsZ density increases during division, in accord with model results. The mechanism is akin to van der Waals picture of gas-liquid condensation, and shows that organisms can exploit microphase transitions to generate mechanical forces.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0807963106