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 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).
Romberg
L
L
Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA. Laura_romberg@hms.harvard.edu
Simon
M
M
Erickson
H P
HP
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D004926:Escherichia coli / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000737:chemistry; D006160:Guanosine Triphosphate / Q000378:metabolism; D008854:Microscopy, Electron; D011487:Protein Conformation
D001426:Bacterial Proteins; D001704:Biopolymers; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria; D006150:Guanine Nucleotides; D006160:Guanosine Triphosphate