Affordable Access

Publisher Website

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

Authors
Journal
The Journal of Cell Biology
0021-9525
Publisher
The Rockefeller University Press
Publication Date
Volume
169
Issue
2
Identifiers
DOI: 10.1083/jcb.200410027
Keywords
  • Research Articles
  • Report
Disciplines
  • Biology

Abstract

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 μM was indicated by light scattering experiments and extrapolation of GTPase versus concentration, thus suggesting a cooperative assembly mechanism.

There are no comments yet on this publication. Be the first to share your thoughts.