Transferases;
Transferring one-carbon groups;
Methyltransferases
BRITE hierarchy

S-adenosyl-L-methionine:tRNA (cytosine-C5)-methyltransferase

(1) S-adenosyl-L-methionine + cytosine34 in tRNA precursor = S-adenosyl-L-homocysteine + 5-methylcytosine34 in tRNA precursor [RN:R00595];
(2) S-adenosyl-L-methionine + cytosine40 in tRNA precursor = S-adenosyl-L-homocysteine + 5-methylcytosine40 in tRNA precursor;
(3) S-adenosyl-L-methionine + cytosine48 in tRNA = S-adenosyl-L-homocysteine + 5-methylcytosine48 in tRNA;
(4) S-adenosyl-L-methionine + cytosine49 in tRNA = S-adenosyl-L-homocysteine + 5-methylcytosine49 in tRNA

R00595
Reaction

S-adenosyl-L-methionine [CPD:C00019];
cytosine34 in tRNA precursor;
cytosine40 in tRNA precursor;
cytosine48 in tRNA;
cytosine49 in tRNA

The enzyme from Saccharomyces cerevisiae is responsible for complete 5-methylcytosine methylations of yeast tRNA. The incidence of modification depends on the cytosine position in tRNA. At positions 34 and 40, 5-methylcytosine is found only in two yeast tRNAs (tRNALeu(CUA) and tRNAPhe(GAA), respectively), whereas most other elongator yeast tRNAs bear either 5-methylcytosine48 or 5-methylcytosine49, but never both in the same tRNA molecule [1]. The formation of 5-methylcytosine34 and 5-methylcytosine40 is a strictly intron-dependent process, whereas the formation of 5-methylcytosine48 and 5-methylcytosine49 is an intron-independent process [2,3].

EC 2.1.1.202 created 1976 as EC 2.1.1.29, part transferred 2011 to EC 2.1.1.202

1  [PMID:10445884]

2  [PMID:9207014]

3  [PMID:3537724]

4  [PMID:17475914]