Apparent cooperative assembly of the bacterial cell division protein FtsZ demonstrated by isothermal titration calorimetry.

Journal Article (Journal Article)

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.

Full Text

Duke Authors

Cited Authors

  • Caplan, MR; Erickson, HP

Published Date

  • April 18, 2003

Published In

Volume / Issue

  • 278 / 16

Start / End Page

  • 13784 - 13788

PubMed ID

  • 12566454

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M300860200


  • eng

Conference Location

  • United States