title: Essentiality Assessment of Cysteinyl and Lysyl-tRNA Synthetases of Mycobacterium smegmatis.
abstract: Discovery of mupirocin, an antibiotic that targets isoleucyl-tRNA synthetase, established aminoacyl-tRNA synthetase as an attractive target for the discovery of novel antibacterial agents. Despite a high degree of similarity between the bacterial and human aminoacyl-tRNA synthetases, the selectivity observed with mupirocin triggered the possibility of targeting other aminoacyl-tRNA synthetases as potential drug targets. These enzymes catalyse the condensation of a specific amino acid to its cognate tRNA in an energy-dependent reaction. Therefore, each organism is expected to encode at least twenty aminoacyl-tRNA synthetases, one for each amino acid. However, a bioinformatics search for genes encoding aminoacyl-tRNA synthetases from Mycobacterium smegmatis returned multiple genes for glutamyl (GluRS), cysteinyl (CysRS), prolyl (ProRS) and lysyl (LysRS) tRNA synthetases. The pathogenic mycobacteria, namely, Mycobacterium tuberculosis and Mycobacterium leprae, were also found to possess two genes each for CysRS and LysRS. A similar search indicated the presence of additional genes for LysRS in gram negative bacteria as well. Herein, we describe sequence and structural analysis of the additional aminoacyl-tRNA synthetase genes found in M. smegmatis. Characterization of conditional expression strains of Cysteinyl and Lysyl-tRNA synthetases generated in M. smegmatis revealed that the canonical aminoacyl-tRNA synthetase are essential, while the additional ones are not essential for the growth of M. smegmatis.
authors.affiliation: AstraZeneca India Pvt Ltd, Bellary Road, Hebbal, Bengaluru, 560024, India.
authors.forename: Sudha
authors.initials: S
authors.lastname: Ravishankar
authors.affiliation: AstraZeneca India Pvt Ltd, Bellary Road, Hebbal, Bengaluru, 560024, India.
authors.forename: Anisha
authors.initials: A
authors.lastname: Ambady
authors.affiliation: School of Biosciences & Technology, VIT University, Vellore, 632014, India.
authors.forename: Rayapadi G
authors.initials: RG
authors.lastname: Swetha
authors.affiliation: School of Biosciences & Technology, VIT University, Vellore, 632014, India.
authors.forename: Anand
authors.initials: A
authors.lastname: Anbarasu
authors.affiliation: School of Biosciences & Technology, VIT University, Vellore, 632014, India.
authors.forename: Sudha
authors.initials: S
authors.lastname: Ramaiah
authors.affiliation: AstraZeneca India Pvt Ltd, Bellary Road, Hebbal, Bengaluru, 560024, India.
authors.forename: Vasan K
authors.initials: VK
authors.lastname: Sambandamurthy
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008250:Lysine-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics*; D020102:Mycobacterium smegmatis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D012343:RNA, Transfer / Q000378:metabolism
chemical_list: D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; C019975:cysteinyl-tRNA synthetase; D008250:Lysine-tRNA Ligase