Characterization of the Dual Routes for Bacillus subtilis Aspagainyl‐tRNA Synthesis

Abstract

Attaching asparagine to its cognate transfer RNA (tRNAAsn) is an essential step in protein synthesis. The bacterium Bacillus subtilis encodes two distinct routes for the formation of asparagingyl‐tRNAAsn. In the first pathway, asparaginyl‐tRNA synthetase catalyzes the direct esterification of asparagine tRNAAsn. In the second pathway, a non‐discriminating aspartyl‐tRNA synthetase misaminoacylates tRNAAsnwith aspartate. The aspartyl‐tRNAAsnformed is then transamidated by the amidotransferase GatCAB to form asparaginyl‐tRNAAsn. The non‐discriminating aspartyl‐tRNA synthetase, GatCAB, and tRNAAsnform a complex known as the transamidosome to synthesize Asn on tRNAAsn. Intriguingly, Bacillussubtilis also codes for two distinct tRNAAsnisoacceptors in its genome. Why Bacillus subtilis acquired an asparaginyl‐tRNA synthetase is not clear. We hypothesize that it enables the organism to adapt to different environmental conditions. To test this hypothesis, we have purified the Bacillus subtilis asparaginyl‐tRNA synthetase and transamidosome. We will report on characterizing in vitro the two pathways for asparaginyl‐tRNA synthesis under different physiologically relevant conditions as well as knocking out asnS in the Bacillus subtilis genome that encodes asparaginyl‐tRNA synthetase. The work will provide insight into how bacteria have adapted amino acid metabolism and use in protein synthesis for different environmental niches.Support or Funding InformationNational Science Foundation (MCB‐1615770)