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A cognate tRNA specific conformational change in glutaminyl‐tRNA synthetase and its implication for specificity
Author(s) -
Mandal Amit Kumar,
Bhattacharyya Anusree,
Bhattacharyya Subhra,
Bhattacharyya Tista,
Roy Siddhartha
Publication year - 1998
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560070422
Subject(s) - aminoacylation , transfer rna , conformational change , aminoacyl trna synthetase , biochemistry , chemistry , t arm , binding site , stereochemistry , amino acyl trna synthetases , biology , rna , gene
Conformational changes that occur upon substrate binding are known to play crucial roles in the recognition and specific aminoacylation of cognate tRNA by glutaminyl‐tRNA synthetase. In a previous study we had shown that glutaminyl‐tRNA synthetase labeled selectively in a nonessential sulfhydryl residue by an environment sensitive probe, acrylodan, monitors many of the conformational changes that occur upon substrate binding. In this article we have shown that the conformational change that occurs upon tRNA Gln binding to glnRS/ATP complex is absent in a noncognate tRNA tRNA Glu ‐glnRS/ATP complex. CD spectroscopy indicates that this cognate tRNA Gln ‐induced conformational change may involve only a small change in secondary structure. The Van't Hoff plot of cognate and noncognate tRNA binding in the presence of ATP is similar, suggesting similar modes of interaction. It was concluded that the cognate tRNA induces a local conformational change in the synthetase that may be one of the critical elements that causes enhanced aminoacylation of the cognate tRNA over the noncognate ones.