Poster abstracts
Poster number 161 submitted by Rosella Stower
Investigating the role of transfer RNA 5-cytidine methyltransferases in regulating translation under stress
Rosella Stower (Department of Biological Chemistry, University of Michigan), Kristin S. Koutmou (Department of Chemistry, University of Michigan)
Abstract:
Transfer RNA (tRNA) are highly modified with a variety of post transcriptional chemical 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 the activity of tRNA-modifying enzymes, or how changes to specific tRNA modification sites affect protein synthesis for most modifications. Multiple enzymes add 5-methylcytidine (m5C) to cytosolic tRNA in humans, including the multisite specific 5-cytidine methyltransferase NSUN2. Dysregulation of tRNA modification by NSUN2 is implicated in human diseases including cancers and neurodevelopmental disorders, underscoring the importance of understanding how modification of cytosolic tRNA by NSUN2 influences cellular processes. How m5C levels vary in different cellular contexts, the mechanistic impact of m5C at each site, and how m5C levels on tRNA influence translational output has yet to be defined. Because NSUN2 also modified other classes of RNA including messenger RNA and mitochondrial tRNA, this work will use the S. cerevisiae homologue to understand how m5C addition to cytosolic tRNA by multisite specific methyltransferases affects cellular responses. Towards this goal, we have identified a set of divalent metals that TRM4 deletion alters sensitivity to as a model cellular context and tested the use of nanopore direct RNA sequencing to detect changes in m5C levels. We are additionally interested in the basis for differences in the cellular substrate scope of the human and yeast homologues. While the substrate specificity of NSUN2 has been studied, in this work we will determine the specificity of TRM4 to identify if differences are solely enzymatic or if other regulatory mechanisms are at play. Overall, this work will broaden our understanding of how tRNA modifications and their associated writer enzymes contribute to globally altering translation in different cellular contexts.
Keywords: transfer RNA, RNA modifications