TITLE:
Mechanism and evolution of multidomain aminoacyl-tRNA synthetases revealed by their inhibition by analogues of a reaction intermediate, and by properties of truncated forms
AUTHORS:
Jacques Lapointe
KEYWORDS:
Multidomain Enzymes; tRNA; Aminoacyl-tRNA Synthetases; Truncated Enzymes; Steady-State Kinetics; Inhibitors; Mechanism; Evolution
JOURNAL NAME:
Journal of Biomedical Science and Engineering,
Vol.6 No.10,
October
4,
2013
ABSTRACT: Many enzymes which catalyze the conversion of large substrates are made of several structural domains belonging to the same polypeptide chain. Transfer RNA (tRNA), one of the substrates of the multidomain aminoacyl-tRNA synthetases (aaRS), is an L-shaped molecule whose size in one dimension is similar to that of its cognate aaRS. Crystallographic structures of aaRS/tRNA complexes show that these enzymes use several of their structural domains to interact with their cognate tRNA. This mini review discusses first some aspects of the evolution and of the flexibility of the pentadomain bacterial glutamyl-tRNA synthetase (GluRS) revealed by kinetic and interaction studies of complementary truncated forms, and then illustrates how stable analogues of aminoacyl-AMP intermediates have been used to probe conformational changes in the active sites of Escherichia coli GluRS and of the nondiscriminating aspartyl-tRNA synthetase (ND-AspRS) of Pseudomonas aeruginosa.