Journal of Biological Chemistry
Volume 282, Issue 49, 7 December 2007, Pages 35629-35637
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Protein Synthesis, Post-Translational Modification, and Degradation
Kinetics of the Interactions between Yeast Elongation Factors 1A and 1Bα, Guanine Nucleotides, and Aminoacyl-tRNA*

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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 μm, 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 (107–108 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-tRNAPhe with a Kd of 3 nm, whereas eEF1A·GDP shows no significant binding, indicating that eEF1A has similar tRNA binding properties as its prokaryotic homolog, EF-Tu.

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*

The work was supported by the Deutsche Forschungsgemeinschaft (to M. V. R.) and National Institutes of Health Grant R01 GM57483 (to T. G. K.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1

Present address: Inst. of Biophysical Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D-85747 Garching, Germany.