Transfer RNA methyltransferase activity in paramecium aurelia.
The tRNA methyltransferases from Paramecium aurelia were investigated. The effects of varying the Mg2+ and NH4+ concentrations, pH, and temperature on the methylation of Escherichia coli B tRNA using extracts from P. aurelia were determined. Optimum tRNA methyltransferase activity was observed at pH 7.8 and 37 degrees C. The Mg2+ optimum occurred at 0.66 mM in the absence of NH4+ while the NH4+ optimum occurred at 100 mM in the absence of Mg2+. Analysis of the bases methylated in (E. coli B) tRNA by extracts of P. aurelia showed the presence of 1-methyladenine, 1-methylguanine, N2-methylguanine, N2,N2-dimethylguanine and methylated pyrimidine nucleotides. In comparison, an analysis of the in vivo methylation of tRNA from P. aurelia showed the presence of 1-methyladenine, 6-methyladenine, 6,6-dimethyladenine, 1-methylguanine, N2-methylguanine, N2,N2-dimethylguanine, 7-methylguanine, and methylated pyrimidine nucleotides. The pattern of methylation of tRNA in P. aurelia is similar to that observed in other eukaryotes.
D000641:Ammonia / Q000494:pharmacology; D000818:Animals; D006147:Guanine / Q000031:analogs & derivatives / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D010247:Paramecium / Q000187:drug effects / Q000201:enzymology*; D012343:RNA, Transfer / Q000302:isolation & purification; D012436:S-Adenosylmethionine / Q000494:pharmacology; D013696:Temperature; D012359:tRNA Methyltransferases / Q000378:metabolism*
D006147:Guanine; D000641:Ammonia; D012436:S-Adenosylmethionine; D012343:RNA, Transfer; D012359:tRNA Methyltransferases; D008274:Magnesium