Post-transcriptional tRNA modifications are required for proper function. Residues 32 and 34 are 2’-O-methylated to Nm32 and Nm34 respectively in yeast and humans. In yeast, the Trm7 methyltransferase interacts with Trm732 and Trm734 to form Cm32 and Gm34, respectively, on tRNAPhe. Human FTSJ1, the homolog of Trm7, and human THADA, the homolog of Trm732, interact to form Cm32. Mutations in FTSJ1 cause intellectual disability and THADA is linked to polycystic ovary syndrome and type 2 diabetes. We are studying the role of Trm732 in the Trm7 methyltransferase reaction by generating Trm732 variants and assaying their functionality in yeast. Cm32 levels on tRNAs from yeast expressing these variants are quantified to determine whether levels affect cell growth. To determine the biological role of Cm32 and Gm34 on tRNAPhe, we are studying genetic interactions by testing the growth of yeast trm732Δ and trm734Δ double mutants. We find that the genetic interaction of TRM7 and HDA1 or SRC1 is likely due to lack of Gm34, because hda1Δtrm734Δ and src1Δtrm734Δ yeast mutants are sick. We also find that PUB1 interacts with TRM732, but not TRM734. We are currently working to identify the hypomodified tRNA(s) responsible for the growth defect in each of these strains.

Role of Trm732 in tRNA modification and cell growth

255th National Meeting (2018)

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