Catalyzes direct attachment of p-Tyr (Tyr) to tRNAPhe. Permits also, with a lower efficiency, the attachment of m-Tyr to tRNAPhe, thereby opening the way for delivery of the misacylated tRNA to the ribosome and incorporation of ROS-damaged amino acid into proteins.
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.
Human mitochondrial phenylalanyl-tRNA synthetase (mtPheRS) has been identified from the human EST database. Using consensus sequences derived from conserved regions of the alpha and beta-subunits from bacterial PheRS, two partially sequenced cDNA clones were identified. Unexpectedly, sequence analysis indicated that one of these clones was a truncated form of the other. Detailed analysis indicates that unlike the (alphabeta)2 structure of the prokaryotic and eukaryotic cytoplasmic forms of PheRS, the human mtPheRS consists of a single polypeptide chain. This protein has been cloned and expressed in Escherichia coli. Gel filtration and analytical velocity sedimentation centrifugation indicate that the human mtPheRS is active in a monomeric form. The N-terminal 314 amino acid residues appear to be analogous to the alpha-subunit of the prokaryotic PheRS, while the C-terminal 100 amino acid residues correspond to a region of the beta-subunit known to interact with the anticodon of tRNAPhe. Comparisons with the sequences of PheRS from yeast and Drosophila mitochondria indicate they are 42 % and 51 % identical with the human mtPheRS, respectively. Sequence analysis confirms the presence of motifs characteristic of class II aminoacyl-tRNA synthetases. KM and kcat values for ATP:PPi exchange and for the aminoacylation reaction carried out by human mtPheRS have been determined. Evolutionary origins of this small monomeric human mtPheRS are unknown, however, implications are that this enzyme is a result of the simplification of the more complex (alphabeta)2 bacterial PheRS in which specific functional regions were retained.
Human mitochondrial phenylalanyl-tRNA synthetase (mtPheRS) has been identified from the human EST database. Using consensus sequences derived from conserved regions of the alpha and beta-subunits from bacterial PheRS, two partially sequenced cDNA clones were identified. Unexpectedly, sequence analysis indicated that one of these clones was a truncated form of the other. Detailed analysis indicates that unlike the (alphabeta)2 structure of the prokaryotic and eukaryotic cytoplasmic forms of PheRS, the human mtPheRS consists of a single polypeptide chain. This protein has been cloned and expressed in Escherichia coli. Gel filtration and analytical velocity sedimentation centrifugation indicate that the human mtPheRS is active in a monomeric form. The N-terminal 314 amino acid residues appear to be analogous to the alpha-subunit of the prokaryotic PheRS, while the C-terminal 100 amino acid residues correspond to a region of the beta-subunit known to interact with the anticodon of tRNAPhe. Comparisons with the sequences of PheRS from yeast and Drosophila mitochondria indicate they are 42 % and 51 % identical with the human mtPheRS, respectively. Sequence analysis confirms the presence of motifs characteristic of class II aminoacyl-tRNA synthetases. KM and kcat values for ATP:PPi exchange and for the aminoacylation reaction carried out by human mtPheRS have been determined. Evolutionary origins of this small monomeric human mtPheRS are unknown, however, implications are that this enzyme is a result of the simplification of the more complex (alphabeta)2 bacterial PheRS in which specific functional regions were retained.
The process of coupling phenylalanine to phenylalanyl-tRNA, catalyzed by phenylalanyl-tRNA synthetase. In tRNA aminoacylation, the amino acid is first activated by linkage to AMP and then transferred to either the 2'- or the 3'-hydroxyl group of the 3'-adenosine residue of the tRNA.
Human mitochondrial phenylalanyl-tRNA synthetase (mtPheRS) has been identified from the human EST database. Using consensus sequences derived from conserved regions of the alpha and beta-subunits from bacterial PheRS, two partially sequenced cDNA clones were identified. Unexpectedly, sequence analysis indicated that one of these clones was a truncated form of the other. Detailed analysis indicates that unlike the (alphabeta)2 structure of the prokaryotic and eukaryotic cytoplasmic forms of PheRS, the human mtPheRS consists of a single polypeptide chain. This protein has been cloned and expressed in Escherichia coli. Gel filtration and analytical velocity sedimentation centrifugation indicate that the human mtPheRS is active in a monomeric form. The N-terminal 314 amino acid residues appear to be analogous to the alpha-subunit of the prokaryotic PheRS, while the C-terminal 100 amino acid residues correspond to a region of the beta-subunit known to interact with the anticodon of tRNAPhe. Comparisons with the sequences of PheRS from yeast and Drosophila mitochondria indicate they are 42 % and 51 % identical with the human mtPheRS, respectively. Sequence analysis confirms the presence of motifs characteristic of class II aminoacyl-tRNA synthetases. KM and kcat values for ATP:PPi exchange and for the aminoacylation reaction carried out by human mtPheRS have been determined. Evolutionary origins of this small monomeric human mtPheRS are unknown, however, implications are that this enzyme is a result of the simplification of the more complex (alphabeta)2 bacterial PheRS in which specific functional regions were retained.
Human mitochondrial phenylalanyl-tRNA synthetase (mtPheRS) has been identified from the human EST database. Using consensus sequences derived from conserved regions of the alpha and beta-subunits from bacterial PheRS, two partially sequenced cDNA clones were identified. Unexpectedly, sequence analysis indicated that one of these clones was a truncated form of the other. Detailed analysis indicates that unlike the (alphabeta)2 structure of the prokaryotic and eukaryotic cytoplasmic forms of PheRS, the human mtPheRS consists of a single polypeptide chain. This protein has been cloned and expressed in Escherichia coli. Gel filtration and analytical velocity sedimentation centrifugation indicate that the human mtPheRS is active in a monomeric form. The N-terminal 314 amino acid residues appear to be analogous to the alpha-subunit of the prokaryotic PheRS, while the C-terminal 100 amino acid residues correspond to a region of the beta-subunit known to interact with the anticodon of tRNAPhe. Comparisons with the sequences of PheRS from yeast and Drosophila mitochondria indicate they are 42 % and 51 % identical with the human mtPheRS, respectively. Sequence analysis confirms the presence of motifs characteristic of class II aminoacyl-tRNA synthetases. KM and kcat values for ATP:PPi exchange and for the aminoacylation reaction carried out by human mtPheRS have been determined. Evolutionary origins of this small monomeric human mtPheRS are unknown, however, implications are that this enzyme is a result of the simplification of the more complex (alphabeta)2 bacterial PheRS in which specific functional regions were retained.
Protein involved in the biosynthesis of proteins from mRNA molecules. This process, called translation, is carried out by ribosomes, where activated amino acids are added to the nascent polypeptide chain.
Enzyme that activates an amino acid for translation by forming an aminoacyladenylate intermediate and then links this activated amino acid to the corresponding tRNA molecule (amino acid-tRNA, aminoacyl- tRNA). In general, a specific aminoacyl-tRNA synthase is available for each amino acid.
Enzyme that catalyzes the joining of two molecules coupled with the breakdown of a pyrophosphate bond in ATP or a similar triphosphate. Sometimes the terms "synthase", "synthetase" or "carboxylase" are also used for this class of enzymes.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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