Essentiality Assessment of Cysteinyl and Lysyl-tRNA Synthetases of Mycobacterium smegmatis

• Published in: PloS one Vol. 11; no. 1; p. e0147188
• Main Authors: Ravishankar, Sudha, Ambady, Anisha, Swetha, Rayapadi G., Anbarasu, Anand, Ramaiah, Sudha, Sambandamurthy, Vasan K.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21.01.2016; Public Library of Science (PLoS)
• Subjects: Acids; Amino acids; Amino Acyl-tRNA Synthetases - chemistry; Amino Acyl-tRNA Synthetases - genetics; Amino Acyl-tRNA Synthetases - metabolism; Aminoacyl-tRNA ligase; Aminoacyl-tRNA synthetases; Antibacterial agents; Antibiotics; Antimicrobial agents; Bacteria; Bioinformatics; Biology and Life Sciences; E coli; Enzymes; Gene expression; Genes; Genetic aspects; Glutamate receptors; Glutamic acid receptors; Glycerol; Gram-negative bacteria; Humans; Isoleucine-tRNA ligase; Leprosy; Lysine-tRNA Ligase - chemistry; Lysine-tRNA Ligase - genetics; Lysine-tRNA Ligase - metabolism; Medicine and Health Sciences; Mupirocin; Mutation - genetics; Mycobacteria; Mycobacterium smegmatis; Mycobacterium smegmatis - enzymology; Mycobacterium smegmatis - genetics; Mycobacterium smegmatis - growth & development; Mycobacterium tuberculosis; Physiological aspects; Proteins; Research and Analysis Methods; RNA, Transfer - metabolism; Staphylococcus aureus; Structural analysis; Transfer RNA; tRNA; Tuberculosis; India; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0147188

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.