Polymerization of Ftsz, a bacterial homolog of tubulin. is assembly cooperative?

FtsZ is a bacterial homolog of tubulin that is essential for prokaryotic cytokinesis. In vitro, GTP induces FtsZ to assemble into straight, 5-nm-wide polymers. Here we show that the polymerization of these FtsZ filaments most closely resembles noncooperative (or "isodesmic") assembly; the...

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Bibliographic Details
Published in:The Journal of biological chemistry 2001-04, Vol.276 (15), p.11743-11753
Main Authors: Romberg, L, Simon, M, Erickson, H P
Format: Article
Language:English
Subjects:
Bacterial Proteins - chemistry
Bacterial Proteins - metabolism
Bacterial Proteins - ultrastructure
Biopolymers - chemistry
Biopolymers - metabolism
Cytoskeletal Proteins
Escherichia coli - metabolism
FtsZ protein
Guanine Nucleotides - chemistry
Guanosine Triphosphate - metabolism
Microscopy, Electron
Protein Conformation
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Summary:FtsZ is a bacterial homolog of tubulin that is essential for prokaryotic cytokinesis. In vitro, GTP induces FtsZ to assemble into straight, 5-nm-wide polymers. Here we show that the polymerization of these FtsZ filaments most closely resembles noncooperative (or "isodesmic") assembly; the polymers are single-stranded and assemble with no evidence of a nucleation phase and without a critical concentration. We have developed a model for the isodesmic polymerization that includes GTP hydrolysis in the scheme. The model can account for the lengths of the FtsZ polymers and their maximum steady state nucleotide hydrolysis rates. It predicts that unlike microtubules, FtsZ protofilaments consist of GTP-bound FtsZ subunits that hydrolyze their nucleotide only slowly and are connected by high affinity longitudinal bonds with a nanomolar K(D).
ISSN:0021-9258
DOI:10.1074/jbc.M009033200