Open AccessInterpretation of tRNA‐Mischarging Kinetics
Author(s) -
DIETRICH Andrè,
KERN Daniel,
BONNET Jacques,
GIEGÉ Richard,
EBEL JeanPierre
Publication year - 1976
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1976.tb10965.x
Subject(s) - aminoacylation , transfer rna , yeast , acylation , kinetics , chemistry , ionic strength , biology , biochemistry , rna , catalysis , organic chemistry , physics , quantum mechanics , aqueous solution , gene
Incorrect tRNA aminoacylation reactions are characterized by very slow reaction rates and by the fact that in most cases they are incomplete. In a previous study some of us explained the incompleteness of the correct aminoacylation reactions of tRNA, which can be encountered under certain experimental conditions (for instance low enzyme concentration or high ionic strength) by an equilibrium between the aminoacylation and the deacylation reactions [J. Bonnet and J. P. Ebel (1972) Eur. J. Biochem. 31 , 335–344]. In the present report we bring evidence that the incorrect valylation of yeast tRNA 1 Met by yeast valyl‐tRNA synthetase studied under standard experimental conditions, can also be described by a kinetic rate law including the rate equations of the aminoacylation and of the various deacylation reactions. In particular we show that the incomplete mischarging plateaus reflect the existence of art equilibrium between the valylation reaction on the one hand and the spontaneous and enzymic deacylation of valyl‐tRNA f Met and the reverse of the valylation reaction on the other hand. However, when the valyl‐tRNA synthetase concentration is not very high the reverse reaction of the aminoacylation does not play a predominant part in the establishment of the plateau. These interpretations have been extended to other mischarging systems: valylation of yeast tRNA Phe by yeast valyl‐tRNA synthetase and mischarging of tRNA f Met and tRNA 2Val from yeast by yeast phenylalanyl‐tRNA synthetase. Unusual mischarging kinetics have been discussed. Furthermore, and as in correct systems, we found that during the mischarging of tRNA f Met one ATP is hydrolyzed per tRNA charged with valine. We conclude that the correct and the incorrect aminoacylation of tRNA behave kinetically in a similar way.