In vitro assembly and GTP hydrolysis by bacterial tubulins BtubA and BtubB.

Journal Article

Arecent study identified genuine tubulin proteins, BtubA and BtubB, in the bacterial genus Prosthecobacter. We have expressed BtubA and BtubB in Escherichia coli and studied their in vitro assembly. BtubB by itself formed rings with an outer diameter of 35-36 nm in the presence of GTP or GDP. Mixtures of BtubB and BtubA formed long protofilament bundles, 4-7 protofilaments wide (20-30 protofilaments in the three-dimensional bundle). Regardless of the starting stoichiometry, the polymers always contained equal concentrations of BtubA and BtubB, suggesting that BtubA and B alternate along the protofilament. BtubA showed negligible GTP hydrolysis, whereas BtubB hydrolyzed 0.40 mol GTP per min per mol BtubB. This GTPase activity increased to 1.37 per min when mixed 1:1 with BtubA. A critical concentration of 0.4-1.0 microM was indicated by light scattering experiments and extrapolation of GTPase versus concentration, thus suggesting a cooperative assembly mechanism.

Full Text

Duke Authors

Cited Authors

  • Sontag, CA; Staley, JT; Erickson, HP

Published Date

  • April 25, 2005

Published In

Volume / Issue

  • 169 / 2

Start / End Page

  • 233 - 238

PubMed ID

  • 15851515

International Standard Serial Number (ISSN)

  • 0021-9525

Digital Object Identifier (DOI)

  • 10.1083/jcb.200410027

Language

  • eng

Conference Location

  • United States