Poster abstracts
Poster number 3 submitted by Isobel Bowles
Identification of a tRNA-specific function for the tRNA methyltransferase Trm10 in Saccharomyces cerevisiae
Isobel Bowles (OSBP)
Abstract:
tRNA methyltransferase 10 (Trm10) methylates N1 of guanosine at the 9th position of tRNA molecules using methyl donor S-adenosyl methionine (SAM). Upon deletion of TRM10, Saccharomyces cerevisiae strains exhibit growth defects in the presence of antitumor drug 5-fluorouracil (5FU). We hypothesized that tRNA stability decreases with the lack of the m1G9 modification in trm10Δ strains and that certain tRNA species are more reliant upon the presence of the methylated G9 nucleotide, as evident from different growth phenotypes observed upon tRNA overexpression. When Trm10 substrate tRNATrp is overexpressed in trm10Δ strains, growth hypersensitivity to 5FU is rescued, while overexpression of other tRNA species in S. cerevisiae do not display a growth rescue. We demonstrated that levels of tRNATrp decrease in trm10Δ strains and that overexpression of tRNATrp recovers tRNATrp levels in trm10Δ strains, while another Trm10 substrate (tRNAGly) remains at a similar level in all strains. The specific role of the m1G9 tRNA modification is being investigated by analyzing known mechanisms of tRNATrp quality control, using S. cerevisiae trm10Δ strains with 5FU. tRNA structures that correlate with active substrates for Trm10 activity are also being determined with nuclease and chemical footprinting, as well as 2’ hydroxyl acylation analyzed by primer extension (SHAPE). Together these studies provide further understanding of tRNA structural elements that promote methylation by Trm10 and the biological impact of loss of this highly conserved modification.
Keywords: tRNA modification, tRNA levels, SHAPE