Biopolymers and cell. 2002; 18 (1): 71 - 75

The role of nucleotides in position 1 and 72 of the tRNATyr acceptor stem in aminoacylation by bovine tyrosyl-tRNA synthetase

K G. Naidenov, M. I. Vudmaska, G. Kh, Matsuka

In order to investigate the contribution of each nudeotide of the first base-pare of bovine tRNA yr acceptor stem in tyrosine identity the set of mutant in vitro transcripts were prepared. Kinetic parameters of the tyrosylation for each transcript were determined using recombinant bovine tyrosyl-tRNA synthetase overproduced in bacte¬rial system and purified by means of C-terminal 6xHis tag. It was found that transcript with first pair G1-G72 shows nearly the same catalytic efficiency as wild-type transcript CJ-G72, whereas C in position 72 completely abolishes tyrosylation regardless of C or G located in 1st position. A or U in position 72 decrease acceptor activity to a lesser extent, with U72 having the more evident effect, also with weak dependence on nudeotide in 1st position. Basing on this results we suggest that contribution of the first base-pair to bovine tRNA yr identity rely mainly on the guanosine in position 72.