Mutation of a conserved CDK site converts a metazoan Elongation Factor 1Bβ subunit into a replacement for yeast eEF1Bα

• Published in: Molecular genetics and genomics : MGG 2003-08, Vol.269 (6), p.776-788
• Main Authors: Pomerening, J. R., Valente, L., Kinzy, T. G., Jacobs, T. W.
• Format: Article
• Language: English
• Subjects: cyclin-dependent kinase; Elongation factor eEF-1B beta; Elongation factor EF-1B beta; guanine nucleotide exchange factor; Oryza sativa; Pisum sativum; Saccharomyces cerevisiae
• ISSN: 1617-4615; 1617-4623
• DOI: 10.1007/s00438-003-0888-1

Elongation factor subunit eEF1B beta (formerly EF-1 beta in plants and EF-1 delta in animals) was identified and cloned in a screen for proteins from pea that interact with a cyclin-dependent kinase (CDK). CDKs are enzymes that regulate progression through meiotic and mitotic cell cycles in eukaryotes. eEF1B beta and the related protein eEF1B alpha (formerly EF-1 beta ' in plants and EF-1 beta in animals and fungi) can catalyze GTP/GDP exchange on the G-protein eEF1A (formerly EF-1 alpha in plants, animals and fungi) during the elongation phase of protein synthesis in eukaryotes. Recombinant Cdc2 and its native homologues from pea extracts associated both in vitro and in vivo with eEF1B beta . A Cdc2-cyclin B complex phosphorylated recombinant plant eEF1B beta s, but not eEF1B alpha . These interactions between CDK and eEF1B beta prompted investigations into the in vivo consequences of this relationship. Expression of cDNAs encoding rice or pea eEF1B beta subunits failed to complement a Saccharomyces cerevisiae mutant deleted for the eEF1B alpha gene, as was previously observed for the human eEF1B beta . However, replacement of Thr91, the sole consensus CDK phosphorylation site in pea eEF1B beta , with alanine allowed the pea protein to substitute for eEF1B alpha function in vivo. In addition, this rescued strain was severely cold sensitive, and more sensitive to translational inhibitors than wild-type yeast. Taken together, these results suggest a physiological connection between the cyclin-dependent class of kinases and a translational elongation factor in mitotic cells, and provide the first in vivo evidence that an altered form of eEF1B beta can serve as the guanine nucleotide exchange factor for eEF1A.