The human tRNA m5C methyltransferase Misu is multisite-specific

 Abstract

The human tRNA m5C methyltransferase Misu is a novel downstream target of the proto-oncogene Myc that participates in controlling cell division and proliferation. Misu catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to carbon 5 of cytosines in tRNAs. It was previously shown to catalyze in vitro the intron-dependent formation of m5C at the first position of the anticodon (position 34) within the human pre-tRNALeu(CAA). In addition, it was recently reported that C48 and C49 are methylated in vivo by Misu. We report here the expression of hMisu in Escherichia coli and its purification to homogeneity. We show that this enzyme methylates position 48 in tRNALeu(CAA) with or without intron and positions 48, 49 and 50 in tRNAGly2(GCC) in vitro. Therefore, hMisu is the enzyme responsible for the methylation of at least four cytosines in human tRNAs. By comparison, the orthologous yeast enzyme Trm4 catalyzes the methylation of carbon 5 of cytosine at positions 34, 40, 48 or 49 depending on the tRNAs.

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1331 - 1338
doi
10.4161/rna.22180
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The human tRNA m5C methyltransferase Misu is multisite-specific