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Publication Abstract from PubMed

The accumulation of proteins damaged by reactive oxygen species (ROS), conventionally regarded as having pathological potentials, is associated with age-related diseases such as Alzheimer's, atherosclerosis, and cataractogenesis. Exposure of the aromatic amino acid phenylalanine to ROS-generating systems produces multiple isomers of tyrosine: m-tyrosine (m-Tyr), o-tyrosine (o-Tyr), and the standard p-tyrosine (Tyr). Previously it was demonstrated that exogenously supplied, oxidized amino acids could be incorporated into bacterial and eukaryotic proteins. It is, therefore, likely that in many cases, in vivo-damaged amino acids are available for de novo synthesis of proteins. Although the involvement of aminoacyl-tRNA synthetases in this process has been hypothesized, the specific pathway by which ROS-damaged amino acids are incorporated into proteins remains unclear. We provide herein evidence that mitochondrial and cytoplasmic phenylalanyl-tRNA synthetases (HsmtPheRS and HsctPheRS, respectively) catalyze direct attachment of m-Tyr to tRNA(Phe), thereby opening the way for delivery of the misacylated tRNA to the ribosome and incorporation of ROS-damaged amino acid into eukaryotic proteins. Crystal complexes of mitochondrial and bacterial PheRSs with m-Tyr reveal the net of highly specific interactions within the synthetic and editing sites.

Eukaryotic cytosolic and mitochondrial phenylalanyl-tRNA synthetases catalyze the charging of tRNA with the meta-tyrosine.,Klipcan L, Moor N, Kessler N, Safro MG Proc Natl Acad Sci U S A. 2009 Jul 7;106(27):11045-8. Epub 2009 Jun 22. PMID:19549855^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.