Year: 2012
Type: article
Abstract: Aminoacyl-tRNA synthetases (aaRSs) play an important role in translation by accurately pairing amino acids with their cognate tRNAs, thereby providing the ribosome with building blocks for protein synthesis.To minimize errors in translation, synthetases achieve the amino acid substrate specificity either by preferentially binding the cognate amino acid and/or by selectively editing the near-cognate amino acids.Defects in aaRS editing can reduce the overall translational fidelity causing growth defects in bacteria, apoptosis and neurodegeneration in mammalian cells.In this work we have studied the roles of the editing domain of Escherichia coli prolyl-tRNA synthetase (ProRS) and its freestanding paralog, YbaK, in maintaining translation accuracy.The synthetic active site of E. coli ProRS acts as a coarse sieve by misactivating noncognate amino acids Ala and Cys along with cognate Pro.The cis-editing domain of bacterial ProRS (INS) is a fine sieve and can only edit smaller Ala-tRNA Pro .The Cys paradox is solved by YbaK, which specifically deacylates Cys-tRNA Pro in trans, employing a novel "triple-sieve" editing mechanism in bacteria.Using biochemical and computational approaches, we have probed the substrate specificities and mechanisms of these homologous editing domains.Our studies suggest that INS catalyzes hydrolysis of Ala-tRNA via a steric exclusion-based sieve, which is hydrophobic in nature and whose specificity can be re-engineered by mutagenesis implying that a general water-catalyzed DEDICATION Dedicated to my family, especially to Maa and my husband Ayan, and to the loving memory of my aunt Sona, without whom, this journey would never have begun v ACKNOWLEDGEMENTS I would like to express my deepest gratitude to my advisor, Prof. Karin Musier-Forsyth, for her endless support and guidance over the years during my graduate studies at OSU.I am grateful to her for not only providing a great research atmosphere to us but also making it scientifically motivating at times.She has always encouraged an independent mind and has given us the freedom to explore our own ideas but at the same time guided us so that we maintain our focus.Her patience, support, faith in me and motivation has kept me going even during my crisis situations at both personal and professional fronts.I take this opportunity as a fortunate one for being able to work with a great person and an excellent mentor.
Author: Mom Das
Institution: The Ohio State University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2222000419