Poster abstracts
Poster number 77 submitted by Abigail Kelly
Investigating tRNA maturation by Protein-Only RNase P (PRORP) & the Elucidating the Role of Interacting Methyltransferases in Arabidopsis thaliana
Abigail Kelly (Chemistry, University of Michigan)
Abstract:
Ribonuclease Proteins (RNase Ps) are a class of enzymes responsible for cleaving the 5' leader sequence of premature tRNAs (pre-tRNA). In 1998, a subclass of RNase P was discovered in the human mitochondria, termed protein-only RNase Ps (PRORPs), which were not catalytically driven by RNA. The complex consisted of PRORP, the catalytic center, and two accessory proteins required for efficient cleavage- TRMT10C, a methyltransferase, and SDR5C1, a dehydrogenase. Later, single subunit PRORPs were discovered in non-metazoan eukaryotes. Much of what we know about these enzymes comes from studies in Arabidopsis thaliana. There are three isoforms of PRORPs in this model organism, with At-PRORP1 localizing in the mitochondria and chloroplasts, and At-PRORP2 and At-PRORP3 localizing in the nucleus. While these single subunit PRORPs do not contain accessory proteins like metazoan mitochondrial (mt) RNase P, it was recently discovered that At-PRORP2 interacts with methyltransferases At-TRM1A and At-TRM1B. Knockout of both methyltransferases were found to be lethal to plant growth and pre-tRNA processing. I am currently conducting assays to determine 5' cleavage rates for different At-tRNAs to discover if the enzyme has a sequence or structural preference for cleavage. Additionally, I am working on cloning and purifying At-TRM1A and At-TRM1B to see what effect they have on cleavage rates. It has been shown that miscleavage occurs in vitro for specific tRNAs such as At-tRNACys. I will be investigating which At-tRNAs are prone to miscleavage and if TRM1A and TRM1B can rescue these miscleavage events. My project is aimed to better elucidate the PRORP interactome, as the enzyme was previously thought to act independently.
References:
Arrivé, M. et. al, (2023). A tRNA-modifying enzyme facilitates RNase P activity in Arabidopsis nuclei. Nature Plants, 9, 2031–2041.
Howard, M. J., et. al, (2016). Differential substrate recognition by isozymes of plant protein-only Ribonuclease P. RNA, 22(5), 782–792.
Rossmanith, W., & Karwan, R. M. (1998a). Characterization of human mitochondrial RNase P: Novel aspects in tRNA processing. Biochemical and Biophysical Research Communications, 247(2), 234–241.
Wilhelm, C. et. al, (2024).The protein-only RNase Ps, endonucleases that cleave pre-tRNA: Biological relevance, molecular architectures, substrate recognition and specificity, and protein interactomes. WIRES RNA, 15(2), e1836.
Keywords: RNase P, tRNA modifying enzyme, Cleavage kinetics