?
D-Tyr-tRNA(Tyr) deacylase This family comprises of several D-Tyr-tRNA(Tyr) deacylase proteins. Cell growth inhibition by several d-amino acids can be explained by an in vivo production of d-aminoacyl-tRNA molecules. Escherichia coli and yeast cells express an enzyme, d-Tyr-tRNA(Tyr) deacylase, capable of recycling such d-aminoacyl-tRNA molecules into free tRNA and d-amino acid. Accordingly, upon inactivation of the genes of the above deacylases, the toxicity of d-amino acids increases. Orthologues of the deacylase are found in many cells.The D-aminoacyl-tRNA deacylase (DTD) enzyme is homodimeric with two active sites located at the dimeric interface. Each active site carries an invariant Gly-cisPro dipeptide motif in each monomer. The interaction between the dipeptide motifs from each monomer ensures substrate stereospecificity. This family also includes a subclass of DTDs which is present in Chordata and harbors a Gly-transPro motif. The cis to trans switch is the key to Animal DTDs (ATD) gaining of L-chiral selectivity. This 'gain of function' through relaxation of substrate chiral specificity underlies ATD's capability of correcting the error in tRNA selection.
|