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Non‐hydrolysable GTP‐γ‐S stabilizes the FtsZ polymer in a GDP‐bound state
Author(s) -
Scheffers DirkJan,
Den Blaauwen Tanneke,
Driessen Arnold J. M.
Publication year - 2000
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2000.01791.x
Subject(s) - ftsz , gtp' , guanosine diphosphate , tubulin , guanosine triphosphate , gtpase , cytoskeleton , biology , biophysics , biochemistry , guanosine , microtubule , microbiology and biotechnology , enzyme , cell
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‐γ‐S), has been shown to induce polymerization of FtsZ, whereas in vitro Ca 2+ 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 Ca 2+ . GTP and its non‐hydrolysable analogue GTP‐γ‐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‐γ‐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‐γ‐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.