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Publications [#113203] of Harold P. Erickson

Papers Published

  1. 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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