Non-hydrolysable GTP-gamma-S stabilizes the FtsZ polymer in a GDP-bound state.
FtsZ, a tubulin homologue, forms a cytokinetic ring at the site of cell division in prokaryotes. The ring is thought to consist of polymers that assemble in a strictly GTP-dependent way. GTP, but not guanosine-5'-O-(3-thiotriphosphate) (GTP-gamma-S), has been shown to induce polymerization of FtsZ, whereas in vitro Ca2+ is known to inhibit the GTP hydrolysis activity of FtsZ. We have studied FtsZ dynamics at limiting GTP concentrations in the presence of 10 mM Ca2+. GTP and its non-hydrolysable analogue GTP-gamma-S bind FtsZ with similar affinity, whereas the non-hydrolysable analogue guanylyl-imidodiphosphate (GMP-PNP) is a poor substrate. Preformed FtsZ polymers can be stabilized by GTP-gamma-S and are destabilized by GDP. As more than 95% of the nucleotide associated with the FtsZ polymer is in the GDP form, it is concluded that GTP hydrolysis by itself does not trigger FtsZ polymer disassembly. Strikingly, GTP-gamma-S exchanges only a small portion of the FtsZ polymer-bound GDP. These data suggest that FtsZ polymers are stabilized by a small fraction of GTP-containing FtsZ subunits. These subunits may be located either throughout the polymer or at the polymer ends, forming a GTP cap similar to tubulin.
Scheffers
D J
DJ
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
den Blaauwen
T
T
Driessen
A J
AJ
D001426:Bacterial Proteins / Q000378:metabolism*; D001704:Biopolymers; D003598:Cytoskeletal Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006868:Hydrolysis; D011485:Protein Binding
D001426:Bacterial Proteins; D001704:Biopolymers; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate)