Formation of D-tyrosyl-tRNATyr accounts for the toxicity of D-tyrosine toward Escherichia coli.
D-Tyr-tRNATyr deacylase cleaves the ester bond between a tRNA molecule and a D-amino acid. In Escherichia coli, inactivation of the gene (dtd) encoding this deacylase increases the toxicity of several D-amino acids including D-tyrosine, D-tryptophan, and D-aspartic acid. Here, we demonstrate that, in a Deltadtd cell grown in the presence of 2.4 mm D-tyrosine, approximately 40% of the total tRNATyr pool is converted into D-Tyr-tRNATyr. No D-Tyr-tRNATyr is observed in dtd+ cells. In addition, we observe that overproduction of tRNATyr, tRNATrp, or tRNAAsp protects a Deltadtd mutant strain against the toxic effect of D-tyrosine, D-tryptophan, or D-aspartic acid, respectively. In the case of D-tyrosine, we show that the protection is accounted for by an increase in the concentration of L-Tyr-tRNATyr proportional to that of overproduced tRNATyr. Altogether, these results indicate that, by accumulating in vivo, high amounts of D-Tyr-tRNATyr cause a starvation for L-Tyr-tRNATyr. The deacylase prevents the starvation by hydrolyzing D-Tyr-tRNATyr. Overproduction of tRNATyr also relieves the starvation by increasing the amount of cellular L-Tyr-tRNATyr available for translation.
Soutourina
Olga
O
Laboratoire de Biochimie, Unité Mixte de Recherche 7654, CNRS-Ecole Polytechnique, 91128 Palaiseau Cedex, France.
Soutourina
Julie
J
Blanquet
Sylvain
S
Plateau
Pierre
P
D002384:Catalysis; D026603:D-Aspartic Acid / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism*; D006868:Hydrolysis; D010957:Plasmids / Q000378:metabolism; D014176:Protein Biosynthesis; D012346:RNA, Transfer, Amino Acyl / Q000737:chemistry*; D012365:RNA, Transfer, Tyr / Q000378:metabolism*; D013379:Substrate Specificity; D013997:Time Factors; D014364:Tryptophan / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*
D012346:RNA, Transfer, Amino Acyl; D012365:RNA, Transfer, Tyr; D014443:Tyrosine; D026603:D-Aspartic Acid; D014364:Tryptophan