Computational prediction of the three-dimensional structures for the Caenorhabditis elegans tubulin family

In this article we characterize, from a structural point of view, all 16 members of the tubulin gene family of Caenorhabditis elegans (9 alpha-tubulins, 6 beta-tubulins, and 1 gamma-tubulin). We obtained their tertiary structures by computationally modifying the X-ray crystal structure of the pig brain alpha/beta-tubulin dimer published by Nogales et al. Nature (London) 1998;391:199-203]. Our computational protocol involves changing the amino acids (with MIDAS; Jarvis et al., UCSF MIDAS. University of California, San Francisco, 1986) in the 3D structure of pig brain alpha/beta-tubulin dimer followed by geometry optimization with the AMBER force field (Perlman et al., AMBER 4. University of California, San Francisco, 1990). We subsequently analyze and compare the resulting structures in terms of the differences in their secondary and tertiary structures. In addition, we compare the pattern of hydrogen bonds and hydrophobic contacts in the guanosine triphosphate (GTP)-binding site for all members of the tubulin family. Our computational results show that, except for gamma-tubulin, all members of the C. elegans tubulin family have similar secondary and 3D structures and that the change in the pattern of hydrogen bonds in the GTP-binding site may be used to assess the relative stability of different alpha/beta-tubulin dimers formed by monomers of the tubulin family.