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.
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.