Fluorimetric study of the complex between yeast phenylalanyl-tRNA synthetase and tRNA-Phe. 2. Evidence for an asymmetric behaviour of the enzyme.
The variations of several spectroscopic properties of yeast tRNA-Phe and phenylalanyl-tRNA synthetase upon complex formation, were used to study the stoichiometry of the complex in different experimental conditions. In all cases, for the tRNA-Phe-enzyme complex, in the absence of other ligands, the saturations of the different conformational changes monitored for both macromolecules, are achieved at a 2:1 tRNA/enzyme stoichiometry. Phenylalanine does not modify this saturation. In contrast, the presence of 1 mM ATP induces an asymmetric behaviour of the synthetase: two tRNAs are still bound per enzyme molecule but the conformational change of the latter is completed upon binding of a single tRNA molecule.
D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D001665:Binding Sites; D007700:Kinetics; D008024:Ligands; D010649:Phenylalanine / Q000378:metabolism; D010652:Phenylalanine-tRNA Ligase / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D008024:Ligands; D010649:Phenylalanine; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; D010652:Phenylalanine-tRNA Ligase