Aminoacyl-tRNA synthetases: affinity labeling of the ATP binding site by 2', 3' -ribose oxidized ATP

Abstract

Homogeneous Escherichia coli methionyl-, isoleucyl-, tryptophanyl-, and phenylalanyl-tRNA synthetases and Bacillus stearothermophilus methionyl- and tyrosyl-tRNA synthetases are irreversibly inactivated by reaction of their active ATP sites with the 2',3'-dialdehyde derivative of ATP obtained by periodate oxidation. In each case, the amount of 14C-labeled dialdehyde derivative incorporated per molecule of inactivated enzyme appears consistent with the expected active stoichiometry of the synthetase. These results strongly support the presence, at the active site of the studied aminoacyl-tRNA synthetases, of a common residue, probably a lysine whose epsilon-NH2 group is known, from the work of others, to form a Schiff's base specifically with the 2',3'-dialdehyde derivatives of ribonucleotides.