Kumagai I, Watanabe K, Oshima T
Proc Natl Acad Sci U S A. 1980 Apr;77(4):1922-6. doi: 10.1073/pnas.77.4.1922.
The contents of 2'-O-methylguanosine and 1-methyladenosine in unfractionated tRNA obtained from Thermus thermophilus HB27 were found to increase significantly when the bacterium was grown at a higher temperature (80 degrees C). S-Adenosyl-L-methionine-dependent tRNA (guanosine-2')-methyltransferase (EC 2.1.1.34) and tRNA (adenine-1)-methyltransferase (EC 2.1.1.36) were detected in a cell-free extract of the thermophile, and both of them were partially purified. tRNA (guanosine-2')-methyltransferase specifically catalyzed the methylation of the guanylate residue at position 19 from the 5' end of Escherichia coli tRNAMetf. The amounts of these methyltransferases in the cells and their thermal characteristics seemed to be independent of the growth temperature of the bacterial cells from which the enzymes were extracted. It was inferred that the temperature dependence of the methylation process in vivo is accounted for, not by temperature dependence of enzyme formation, but by that of the enzyme activity.
当嗜热栖热菌HB27在较高温度（80摄氏度）下生长时，从该菌中获得的未分级tRNA中2'-O-甲基鸟苷和1-甲基腺苷的含量显著增加。在该嗜热菌的无细胞提取物中检测到了S-腺苷-L-甲硫氨酸依赖性tRNA（鸟苷-2'）-甲基转移酶（EC 2.1.1.34）和tRNA（腺嘌呤-1）-甲基转移酶（EC 2.1.1.36），并且对它们进行了部分纯化。tRNA（鸟苷-2'）-甲基转移酶特异性催化大肠杆菌tRNAMetf 5'端第19位鸟苷酸残基的甲基化。这些甲基转移酶在细胞中的含量及其热特性似乎与提取这些酶的细菌细胞的生长温度无关。据推测，体内甲基化过程的温度依赖性不是由酶形成的温度依赖性引起的，而是由酶活性的温度依赖性引起的。
