The Crystal Structure of the Glutathione S-Transferase-like Domain of Elongation Factor 1Bγ from Saccharomyces cerevisiae

The crystal structure of the N-terminal 219 residues (domain 1) of the conserved eukaryotic translation elongation factor 1Bgamma (eEF1Bgamma), encoded by the TEF3 gene in Saccharomyces cerevisiae, has been determined at 3.0 A resolution by the single wavelength anomalous dispersion technique. The structure is overall very similar to the glutathione S-transferase proteins and contains a pocket with architecture highly homologous to what is observed in glutathione S-transferase enzymes. The TEF3-encoded form of eEF1Bgamma has no obvious catalytic residue. However, the second form of eEF1Bgamma encoded by the TEF4 gene contains serine 11, which may act catalytically. Based on the x-ray structure and gel filtration studies, we suggest that the yeast eEF1 complex is organized as an [eEF1A.eEF1Balpha.eEF1Bgamma]2 complex. A 23-residue sequence in the middle of eEF1Bgamma is essential for the stable dimerization of eEF1Bgamma and the quaternary structure of the eEF1 complex.