Poster abstracts

Poster number 59 submitted by Rosella Stower

Elucidating the mechanism of Trm4 mediated gene regulation

Rosella Stower (University of Michigan, Department of Biological Cehmistry), Chathuri Pathirage (University of Michigan, Department of Chemistry), Xingchen Liu (University of Michigan, Department of Chemistry), Kristin S. Koutmou (University of Michigan, Department of Chemistry)

Abstract:
Transfer RNA (tRNA) are highly decorated with a variety of post transcriptional modifications that affect their structure and function. The abundance and distribution of these modifications can change in response to stress and other cellular signals and contribute to reshaping the proteome. However, it is still unclear how cells control tRNA-modifying enzymes, or how changes to specific tRNA modification sites affect protein synthesis for most modifications. We are studying the inclusion of 5-methylcytidine (m5C), which is added to cytosolic tRNA at multiple sites by the S-adenosylmethionine dependent methyl transferase TRM4 in S. cerevisiae. trm4Δ cells do not exhibit altered cell growth during normal growth conditions, but TRM4 deletion alters cellular fitness under stress. It has previously been shown that under oxidative stress, TRM4 increases methylation in the anticodon loop of tRNALeu(CAA), leading to the selective upregulation of translation of transcripts that have a higher proportion of their leucine’s encoded by UUG. How this methylation is upregulated under oxidative stress, how m5C changes at other modification sites, what their functional impact is, and what other stress responses TRM4 is involved in remain to be defined. We are working to fill these knowledge gaps by determining how TRM4 selects substrates, identifying further stress conditions for which TRM4 impacts cellular fitness, and discovering the consequences of m5C on translation elongation. Towards this goal, I have identified additional stressors that TRM4 responds to and will use nanopore direct RNA sequencing to identify how m5C changes globally in response to stress. Our work will broaden our understanding of how tRNA modifications and their associated writer enzymes contribute to globally altering translation under stress.

Keywords: transfer RNA, RNA modifications, Stress response