The Interaction Between Arginyl-tRNA Synthetase And TRNA～(Arg)

Arginyl-tRNA synthetase (ArgRS) is unique among all of the class I enyzmes, as the majority of ArgRSs species lacks canonical KMSK sequences. But B. stearothermophilus ArgRS does have. Here we report the cloning the genes encoding B. stearothermophilus ArgRS and tRNA^Arg(ACG) and expression of them in E. coli, followed by purification of the ArgRS and isolation of tRNAArg(ACG). At 55℃the kcat value for the aminoacylation reaction of B. stearothermophilus ArgRS reachs the maximum 17 s^-1,which is 6.6 s^-1 at 37℃. Using three-dimensional modeling in combination with sequence analysis and site-directed mutagenesis in B. stearothermophilus and E. coli ArgRSs, we found a residue upstream of the HIGH sequence in the KMSK-lacking ArgRS motif, which is likely to be a functional counterpart of the second lysine of the KMSK. The results indicate that certain compensation exists between the two sites. So ArgRSs from various sources can be divided into three major groups based on the residue upstream of the HIGH sequence and the canonical KMSK sequences.. Cross-recognition between ArgRSs and tRNAArg(ACG)s from E. coli ,T. thermophilus and B. stearothermophilus was...