Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain; Departamento de Microbiología y Genética, Universidad de Salamanca-Campus Miguel de Unamuno, Salamanca, Spain
Francisco A Balaguer
Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
Andrea E Prota
Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland
Daniel Lucena-Agell
Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
Christina Kamma-Lorger
ALBA synchrotron, CELLS, Cerdanyola del Vallès, Spain
Toshiki Yagi
Department of Life Sciences, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
Hiroyuki Iwamoto
Diffraction and Scattering Division, Japan Synchrotron Radiation Research Institute, Hyogo, Japan
Laurence Duchesne
Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) – UMR 6290, Rennes, France
Isabel Barasoain
Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
Michel O Steinmetz
Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland; University of Basel, Biozentrum, Basel, Switzerland
Microtubules (MTs) are hollow cylinders made of tubulin, a GTPase responsible for essential functions during cell growth and division, and thus, key target for anti-tumor drugs. In MTs, GTP hydrolysis triggers structural changes in the lattice, which are responsible for interaction with regulatory factors. The stabilizing GTP-cap is a hallmark of MTs and the mechanism of the chemical-structural link between the GTP hydrolysis site and the MT lattice is a matter of debate. We have analyzed the structure of tubulin and MTs assembled in the presence of fluoride salts that mimic the GTP-bound and GDP•Pi transition states. Our results challenge current models because tubulin does not change axial length upon GTP hydrolysis. Moreover, analysis of the structure of MTs assembled in the presence of several nucleotide analogues and of taxol allows us to propose that previously described lattice expansion could be a post-hydrolysis stage involved in Pi release.
