Identification of essential amino acid residues of tRNA (Gm18)methyltransferase for methyl-transfer activity

Recent computation analyses have pointed out an existence of conserved amino add motifs among RNA ribose 2'-O-methyltransferases. However, the functions of these motifs are unclear yet We carried out the site-directed mutagenesis studies systematically on Thermus thermophilus HB8 tRNA (Gml8) methyltransferase gene. Subsequent biochemical analyses with purified variant enzymes clearly revealed that five conserved amino add residues (Asn35, Arg41, Glul24, SerlSO, and Asnl52) are involved in S-adenosyl-L-methionine binding. This is for the first time reporting the function of the conserved motifs among RNA ribose 2'-O-methyltransferases