Functional characterization of the D-Tyr-tRNA(Tyr) deacylase from Escherichia coli

The yihZ gene of Escherichia coil is shown to produce a deacylase activity capable of recycling misaminoacylated D-Tyr-tRNA(Tyr). The reaction is spec ific and, under optimal in vitro conditions, proceeds at a rate of 6 s(-1) with a K-m value for the substrate equal to 1 mu M. Cell growth is sensitiv e to interruption of the yihZ gene if D-tyrosine is added to minimal cultur e medium. Toxicity of exogenous D-tyrosine is exacerbated if, in addition t o the disruption of yihZ, the gene of D-amino acid dehydrogenase (dadA) is also inactivated. Orthologs of the yihZ gene occur in many, but not all, ba cteria. In support of the idea of a general role of the D-Tyr-tRNA(Tyr) dea cylase function in the detoxification of cells, similar genes can be recogn ized in Saccharomyces cerevisiae, Caenorhabditis elegans, Arabidopsis thali ana, mouse, and man.