Poster abstracts
Poster number 16 submitted by Ben Jepson
Assessing the biological function of cytoplasmic tRNA methyltransferase (Trm10) enzymes in Danio rerio
Ben Jepson (MCDB)
Abstract:
The m1R9 tRNA methyltransferase family (Trm10), ubiquitous in Archaea and Eukarya, methylates the N-1 atom of the purine nucleotides at position nine of substrate tRNAs. In Saccharomyces cerevisiae, there is only one Trm10 enzyme. However, in higher eukaryotes, several organisms encode multiple Trm10 homologs. Humans, for example, have one mitochondrial (TRMT10C) and two cytoplasmic (TRMT10A and TRMT10B) paralogs. The importance of multiple cytoplasmic homologs is still unknown although mutations in TRMT10A have been implicated in human diseases suggesting non-redundant roles for these homologs. Previous work has shown that human TRMT10A and TRMT10B have different enzymatic activities and substrate specificities in vitro. Based on these observations we hypothesize that these two cytoplasmic enzymes have non-redundant roles in the cell. Here we use Danio rerio (zebrafish), which also encodes two cytoplasmic Trm10 enzymes, as a model organism to investigate their biological function. Preliminary biochemical assays show that zebrafish Trmt10a and Trmt10b display similar enzymatic activities and substrate specificities in vitro. However, only zebrafish Trmt10a is capable of complementing the 5FU hypersensitivity phenotype of a trm10∆ S. cerevisiae strain suggesting the substrate specificities differ in vivo, consistent with the proposed non-redundant roles for these enzymes in vivo. Even with our current knowledge of in vitro activity and involvement with human disease, we have very little understanding of the roles or activities of Trm10 enzymes in any multicellular eukaryote. The goals of this work are a molecular understanding of the differing biological functions of cytoplasmic Trm10 homologs in a multicellular eukaryote, with possible implications for Trm10-associated human disease.
Keywords: tRNA modification, Trm10, m1R9