Examining the Gm18 and m1G Modification Positions in tRNA Sequences

The tRNA structure contains conserved modifications that are responsible for its stability and are involved in the initiation andaccuracy of the translation process. tRNA modification enzymes are prevalent in bacteria, archaea, and eukaryotes. tRNAGm18 methyltransferase (TrmH) and tRNA m1G37 methyltransferase (TrmD) are prevalent and essential enzymes in bacterialpopulations. TrmH involves itself in methylation process at the 2‘-OH group of ribose at the 18th position of guanosine (G)in tRNAs. TrmD methylates the G residue next to the anticodon in selected tRNA subsets. Initially, m1G37 modification wasreported to take place on three conserved tRNA subsets (tRNAArg, tRNALeu, tRNAPro); later on, few archaea and eukaryotesorganisms revealed that other tRNAs also have the m1G37 modification. The present study reveals Gm18, m1G37modification, and positions of m1G that take place next to the anticodon in tRNA sequences. We selected extremophileorganisms and attempted to retrieve the m1G and Gm18 modification bases in tRNA sequences. Results showed that theGm18 modification G residue occurs in all tRNA subsets except three tRNAs (tRNAMet, tRNAPro, tRNAVal). Whereas the m1G37modification base G is formed only on tRNAArg, tRNALeu, tRNAPro, and tRNAHis, the rest of the tRNAs contain adenine (A) nextto the anticodon. Thus, we hypothesize that Gm18 modification and m1G modification occur irrespective of a G residue intRNAs.