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

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Journal of Biological Chemistry

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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.


This article was originally published as Gromadski, K.B., Schümmer, T., Str⌀mgaard, A., Knudsen, C.R., Kinzy, T.G., and Rodnina, M.V. (2007) Kinetics of the Interactions between Yeast Elongation Factors 1A and 1B, Guanine Nucleotides, and Aminoacyl-tRNA. J. Biol. Chem. 282:35629-37. PMC3269240.