Studies on the effects ofin vitro methyiation on aminoacylation of transfer RNA

In vitro methyiation ofEscherichia coli transfer ribonucleic acid by cell free extracts ofMycobacterium smegmatis leads exclusively to the formation of 1-methyl adenine [Vani, B. R., Ramakrishnan, T., Taya, Y., Noguchi, S., Yamaiuzumi, Z. and Nishimura, S. (1978)J. Bact., 137, 1085]. We have studied the effect of this modification on aminoacylationof Escherichia coli tRNA by mycobacterial enzymes. Aminoacylation with total algal protein hydrolysate as well as several individual aminoacids like methionine, valine, tyrosine, aspartic acid and lysine were monitored. In all the cases methyiation had a positive effect on the extent of aminoacylation by mycobacterial enzymes. Decreased aminoacylationin vitro was observed when hypomethylated transfer RNA from ethionine treated cells was used as the substrate for aminoacylation