Poster abstracts
Poster number 52 submitted by Ashanti Matlock
Investigating the molecular basis for substrate recognition by Thg1
Ashanti Matlock (OSBP), Jane Jackman (Chemistry and Biochemistry)
Abstract:
The tRNAHis guanylyltransferase (Thg1) enzyme family is a unique group of proteins that catalyze 3' to 5' nucleotide addition. Present in all domains of life, one major difference among various Thg1 family members is striking differences in their RNA substrate specificities. Thg1, unlike its more promiscuous relatives, TLPs, catalyzes the addition of a single guanine to only tRNAHis out of all tRNA species in the cell. This addition is a critical step in tRNAHIs maturation and necessary for the proper recognition by its cognate aminoacyl synthetase. The anticodon is utilized by Thg1 to recognize tRNAHis as a G-1 addition substrate; however, alanine mutational studies suggests that there are other interactions between tRNAHis and Thg1 that are important for substrate specificity. To determine how Thg1 differentiates substrate and non-substrate, we are using chemical probing to compare the footprints of Thg1 bound to substrate (tRNAHis) and a non- substrate tRNA. Determining interactions that confer substrate specificity, could provide insight into the hypothesized evolution of the essential Thg1 enzyme from an ancestral non-tRNA selective 3’-5’ polymerase to a specialized enzyme whose nucleotide addition is highly specific for a single tRNA.
Keywords: tRNA Modification, Protein-RNA interactions