| Publications [#113203] of Harold P. Erickson
Papers Published
- MR Caplan, HP Erickson, Apparent cooperative assembly of the bacterial cell division protein FtsZ demonstrated by isothermal titration calorimetry.,
The Journal of biological chemistry, United States, vol. 278 no. 16
(April, 2003),
pp. 13784-8, ISSN 0021-9258
(last updated on 2009/02/12)
Abstract: The assembly dynamics of FtsZ, a prokaryotic homolog of tubulin, are important for their role in bacterial cytokinesis. Here we used isothermal titration calorimetry (ITC) to measure the heat of FtsZ self-association under various conditions. The measurements were designed to test whether FtsZ protofilaments are assembled by an isodesmic (linear aggregates in which each bond has an identical equilibrium constant) or a cooperative (aggregates only become stable after forming a oligomeric nucleus) assembly process. The isodesmic model can fit the assembly in GDP closely but cannot fit the assembly in GTP. FtsZ-GTP without Mg(2+) exhibits an apparent critical concentration, which is indicative of cooperative assembly, near 2.9 microm. With 2.5 mm Mg(2+) (which allows FtsZ to hydrolyze GTP) the critical concentration is reduced 10-fold to approximately 0.31 microm. Both with and without Mg(2+) there is no evidence for assembly below the critical concentration, but there is an abrupt transition to full assembly above. The ITC data are highly suggestive of a cooperative assembly, although this is difficult to reconcile with the 1-subunit-thick protofilaments observed by electron microscopy.
Keywords: Bacterial Proteins • Biochemistry • Calorimetry • Cell Division • Cytoskeletal Proteins* • Dimerization • Escherichia coli • Guanosine Diphosphate • Guanosine Triphosphate • Magnesium • Microscopy, Electron • Thermodynamics • Time Factors • chemistry* • metabolism • metabolism* • methods • pharmacology
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