Kinetics of the Interactions between Yeast Elongation Factors 1A and 1Bα, Guanine Nucleotides, and Aminoacyl-tRNA

• Published in: The Journal of biological chemistry Vol. 282; no. 49; p. 35629
• Main Authors: Kirill B. Gromadski, Tobias Schümmer, Anne Strømgaard, Charlotte R. Knudsen, Terri Goss Kinzy, Marina V. Rodnina
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 07-12-2007
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M707245200

The interactions of elongation factor 1A (eEF1A) from Saccharomyces cerevisiae with elongation factor 1Bα (eEF1Bα), guanine nucleotides, and aminoacyl-tRNA were studied kinetically by fluorescence stopped-flow.
eEF1A has similar affinities for GDP and GTP, 0.4 and 1.1 μ m , respectively. Dissociation of nucleotides from eEF1A in the absence of the guanine nucleotide exchange factor is slow (about
0.1 s –1 ) and is accelerated by eEF1Bα by 320-fold and 250-fold for GDP and GTP, respectively. The rate constant of eEF1Bα binding
to eEF1A (10 7 –10 8 m –1 s –1 ) is independent of guanine nucleotides. At the concentrations of nucleotides and factors prevailing in the cell, the overall
exchange rate is expected to be in the range of 6 s –1 , which is compatible with the rate of protein synthesis in the cell. eEF1A·GTP binds Phe-tRNA Phe with a K d of 3 n m , whereas eEF1A·GDP shows no significant binding, indicating that eEF1A has similar tRNA binding properties as its prokaryotic
homolog, EF-Tu.