Clinically Relevant Mutations of Mycobacterial GatCAB Inform Regulation of Translational Fidelity.

Most bacteria employ a two-step indirect tRNA aminoacylation pathway for the synthesis of aminoacylated tRNA and tRNA. The heterotrimeric enzyme GatCAB performs a critical amidotransferase reaction in the second step of this pathway. We have previously demonstrated in mycobacteria that this two-step pathway is error prone and translational errors contribute to adaptive phenotypes such as antibiotic tolerance.

Forward Genetics Reveals a Fusion Polypeptide Causes Mistranslation and Rifampicin Tolerance in .

Most bacteria, including mycobacteria, utilize a two-step indirect tRNA aminoacylation pathway to generate correctly aminoacylated glutaminyl and asparaginyl tRNAs. This involves an initial step in which a non-discriminatory aminoacyl tRNA synthetase misacylates the tRNA, followed by a second step in which the essential amidotransferase, GatCAB, amidates the misacylated tRNA to its correct, cognate form. It had been previously demonstrated that mutations in can mediate increased error rates specifically of glutamine to glutamate or asparagine to aspartate in protein synthesis.

The essential mycobacterial amidotransferase GatCAB is a modulator of specific translational fidelity.

Although regulation of translation fidelity is an essential process, diverse organisms and organelles have differing requirements of translational accuracy, and errors in gene translation serve an adaptive function under certain conditions. Therefore, optimal levels of fidelity may vary according to context. Most bacteria utilize a two-step pathway for the specific synthesis of aminoacylated glutamine and/or asparagine tRNAs, involving the glutamine amidotransferase GatCAB, but it had not been appreciated that GatCAB may play a role in modulating mistranslation rates.