Poster abstracts
Poster number 1 submitted by Thilini Abeywansha
Structural basis of tRNA recognition by arginyl-tRNA-protein transferase 1
Thilini Abeywansha (Case Western Reserve University, School of Medicine, Biochemistry Department, Cleveland, OH), Wei Huang (Case Western Reserve University, School of Medicine, Department of Pharmacology, Cleveland, OH), Xuan Ye (Case Western Reserve University, School of Medicine, Center for RNA Science and Therapeutics, Cleveland, OH ), Xin Lan (Case Western Reserve University, School of Medicine, Biochemistry Department, Cleveland, OH), Allison Nawrocki (Case Western Reserve University, School of Medicine, Biochemistry Department, Cleveland, OH), Yi Zhang, Derek Taylor, Eckhard Jankowsky (Case Western Reserve University, School of MedicineCleveland, OH )
Abstract:
Arginyl-tRNA protein transferase (ATE1) catalyzes the conjugation of arginine to the N-terminal or midchain Glu/Asp residues (also known as arginylation) of its substrates. Protein arginylation is solely mediated by ATE1 in an arginyl-tRNAArg-dependent manner and is a vital post-translational modification in many biological processes. ATE1-mediated arginylation is dysregulated in breast, prostate, skin, and many other cancers. This indicates that ATE1 could be a potential target for cancer therapy, and developing drugs that target ATE1 could be a promising approach to treating cancer. However, the mechanisms by which ATE1 regulates tumorigenesis have yet to be understood due to a lack of understanding of the catalytic mechanism of ATE1. Here, we present our findings on ATE1 structure and the catalytic mechanism as a continuation of our effort to elucidate the role of ATE1 as a tumor suppressor. We solved structures of ATE1 from Saccharomyces cerevisiae (scATE1) in apo form and in complex with tRNAArg using CryoEM. The structure of scATE1 displays overall new folds with a compact conformation consisting of three domains, including a highly conserved GNAT fold, a putative polypeptide substrate binding domain, and a variable domain unique to yeast ATE1. ATE1 interacts with the tRNAArg via helix αf in the assembled complex and mainly contacts the major groove of the tRNAArg acceptor arm, resulting in structural rearrangements of the ATE1 protein. These rearrangements facilitate arginine transfer from the tRNA cofactor to the protein substrate. Based on these data, we propose a detailed catalytic mechanism of ATE1-mediated protein arginylation. Intracellular ATE1 displays a high affinity for arginyl-tRNAArg and leads to the formation of ATE1.arginyl-tRNAArg complex inducing a conformational change in ATE1 and increasing its affinity to protein substrates, which bind weakly to free ATE1. The arginine is then transferred from the tRNA to the protein substrate, generating an arginylated protein and an uncharged tRNA. The reduced affinity of tRNA following the arginine transfer reaction facilitates its release and subsequent recharging by argRS to complete the catalytic cycle.
References:
Abeywansha, T., Huang, W., Ye, X. et al. The structural basis of tRNA recognition by arginyl-tRNA-protein transferase. Nat Commun 14, 2232 (2023). https://doi.org/10.1038/s41467-023-38004-8
Keywords: Arginylation, ATE1, tRNA