title: Rate-limiting guanosine 5'-triphosphate hydrolysis during nucleotide turnover by FtsZ, a prokaryotic tubulin homologue involved in bacterial cell division.
abstract: FtsZ is a prokaryotic tubulin homologue that polymerizes into a dynamic ring during cell division. GTP binding and hydrolysis provide the energy for FtsZ dynamics. However, the precise role of hydrolysis in polymer assembly and turnover is not understood, limiting our understanding of how FtsZ functions in the cell. Here we investigate GTP hydrolysis during the FtsZ polymerization cycle using several complementary approaches that avoid technical caveats of previous studies. We find that at steady state approximately 80% of FtsZ polymer subunits are bound to GTP. In addition, we use pre-steady-state, single turnover assays to directly measure the rate of hydrolysis. Hydrolysis was found to occur at approximately 8/min and to be a rate-limiting step in GTP turnover; phosphate release rapidly followed. These results clarify previously conflicting results in the literature and suggest that pure FtsZ polymers, unlike microtubules, may not be able to undergo dynamic instability or to store energy in the polymer for force production.
authors.affiliation: Department of Cell Biology, Harvard Medical School, 250 Longwood Avenue, Boston, MA 02115, USA. laura.romberg@oberlin.edu
authors.forename: Laura
authors.initials: L
authors.lastname: Romberg
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mitchison
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D002455:Cell Division; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D006150:Guanine Nucleotides / Q000737:chemistry / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000737:chemistry* / Q000378:metabolism*; D006868:Hydrolysis; D011108:Polymers / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D013403:Sugar Phosphates / Q000737:chemistry / Q000378:metabolism; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria; D006150:Guanine Nucleotides; D011108:Polymers; D021122:Protein Subunits; D013403:Sugar Phosphates; D014404:Tubulin; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate