The predatory bacterium Bdellovibrio bacteriovorus aspartyl-tRNA synthetase recognizes tRNAAsn as a substrate

PLoS One. 2014 Oct 22;9(10):e110842. doi: 10.1371/journal.pone.0110842. eCollection 2014.

Abstract

The predatory bacterium Bdellovibrio bacteriovorus preys on other Gram-negative bacteria and was predicted to be an asparagine auxotroph. However, despite encoding asparaginyl-tRNA synthetase and glutaminyl-tRNA synthetase, B. bacteriovorus also contains the amidotransferase GatCAB. Deinococcus radiodurans, and Thermus thermophilus also encode both of these aminoacyl-tRNA synthetases with GatCAB. Both also code for a second aspartyl-tRNA synthetase and use the additional aspartyl-tRNA synthetase with GatCAB to synthesize asparagine on tRNAAsn. Unlike those two bacteria, B. bacteriovorus encodes only one aspartyl-tRNA synthetase. Here we demonstrate the lone B. bacteriovorus aspartyl-tRNA synthetase catalyzes aspartyl-tRNAAsn formation that GatCAB can then amidate to asparaginyl-tRNAAsn. This non-discriminating aspartyl-tRNA synthetase with GatCAB thus provides B. bacteriovorus a second route for Asn-tRNAAsn formation with the asparagine synthesized in a tRNA-dependent manner. Thus, in contrast to a previous prediction, B. bacteriovorus codes for a biosynthetic route for asparagine. Analysis of bacterial genomes suggests a significant number of other bacteria may also code for both routes for Asn-tRNAAsn synthesis with only a limited number encoding a second aspartyl-tRNA synthetase.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aspartate-tRNA Ligase / chemistry*
  • Bacterial Proteins / chemistry*
  • Bdellovibrio / enzymology*
  • Biosynthetic Pathways
  • Escherichia coli
  • Genetic Complementation Test
  • Kinetics
  • RNA, Transfer, Asn / chemistry*
  • Substrate Specificity
  • Transfer RNA Aminoacylation

Substances

  • Bacterial Proteins
  • RNA, Transfer, Asn
  • Aspartate-tRNA Ligase

Grants and funding

This work was supported by the National Science Foundation (MCB-1244326 to KS, www.nsf.gov) and the Skidmore Faculty/Student Summer Research Program (to AA, DG, BU, and KS, http://www.skidmore.edu/dof-vpaa/summer-research/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.