Catalyzes the attachment of the cognate amino acid to the corresponding tRNA in a two-step reaction: the amino acid is first activated by ATP to form a covalent intermediate with AMP and is then transferred to the acceptor end of the cognate tRNA. Component of the GAIT (gamma interferon-activated inhibitor of translation) complex which mediates interferon-gamma-induced transcript-selective translation inhibition in inflammation processes. Upon interferon-gamma activation and subsequent phosphorylation dissociates from the multisynthetase complex and assembles into the GAIT complex which binds to stem loop-containing GAIT elements in the 3'-UTR of diverse inflammatory mRNAs (such as ceruplasmin) and suppresses their translation.
Aminoacyl tRNA synthetases (ARS) catalyze the ligation of amino acids to cognate tRNAs. Chordate ARSs have evolved distinctive features absent from ancestral forms, including compartmentalization in a multisynthetase complex (MSC), noncatalytic peptide appendages, and ancillary functions unrelated to aminoacylation. Here, we show that glutamyl-prolyl-tRNA synthetase (GluProRS), a bifunctional ARS of the MSC, has a regulated, noncanonical activity that blocks synthesis of a specific protein. GluProRS was identified as a component of the interferon (IFN)-gamma-activated inhibitor of translation (GAIT) complex by RNA affinity chromatography using the ceruloplasmin (Cp) GAIT element as ligand. In response to IFN-gamma, GluProRS is phosphorylated and released from the MSC, binds the Cp 3'-untranslated region in an mRNP containing three additional proteins, and silences Cp mRNA translation. Thus, GluProRS has divergent functions in protein synthesis: in the MSC, its aminoacylation activity supports global translation, but translocation of GluProRS to an inflammation-responsive mRNP causes gene-specific translational silencing.
The gamma interferon (IFN-γ)-activated inhibitor of translation (GAIT) complex in human myeloid cells is heterotetrameric, consisting of glutamyl-prolyl-tRNA synthetase (EPRS), NS1-associated protein 1 (NSAP1), ribosomal protein L13a, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The complex binds a structural GAIT element in the 3' untranslated region of VEGF-A and other inflammation-related transcripts and inhibits their translation. EPRS is dually phosphorylated by cyclin-dependent kinase 5 (Cdk5) at Ser(886) and then by a Cdk5-dependent-AGC kinase at Ser(999); L13a is phosphorylated at Ser(77) by death-associated protein kinases DAPK and ZIPK. Because profound differences in inflammatory responses between mice and humans are known, we investigated the GAIT system in mouse macrophages. The murine GAIT complex is heterotrimeric, lacking NSAP1. As in humans, IFN-γ activates the mouse macrophage GAIT system via induced phosphorylation of EPRS and L13a. Murine L13a is phosphorylated at Ser(77) by the DAPK-ZIPK cascade, but EPRS is phosphorylated only at Ser(999). Loss of EPRS Ser(886) phosphorylation prevents NSAP1 incorporation into the GAIT complex. However, the triad of Ser(999)-phosphorylated EPRS, Ser(77)-phosphorylated L13a, and GAPDH forms a functional GAIT complex that inhibits translation of GAIT target mRNAs. Thus, translational control by the heterotrimeric GAIT complex in mice exemplifies the distinctive species-specific responses of myeloid cells to inflammatory stimuli.
In higher eukaryotes, nine aminoacyl-tRNA synthetases are associated within a multienzyme complex which is composed of 11 polypeptides with molecular masses ranging from 18 to 150 kDa. We have cloned and sequenced a cDNA from Drosophila encoding the largest polypeptide of this complex. We demonstrate here that the corresponding protein is a multifunctional aminoacyl-tRNA synthetase. It is composed of three major domains, two of them specifying distinct synthetase activities. The amino and carboxy-terminal domains were expressed separately in Escherichia coli, and were found to catalyse the aminoacylation of glutamic acid and proline tRNA species, respectively. The central domain is made of six 46 amino acid repeats. In prokaryotes, these two aminoacyl-tRNA synthetases are encoded by distinct genes. The emergence of a multifunctional synthetase by a gene fusion event seems to be a specific, but general attribute of all higher eukaryotic cells. This type of structural organization, in relation to the occurrence of multisynthetase complexes, could be a mechanism to integrate several catalytic domains within the same particle. The involvement of the internal repeats in mediating complex assembly is discussed.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionIntAct
J. Biol. Chem. 273, 11267-11273 (1998)[PubMed:9556618]
Tandem repeats located in the human bifunctional glutamyl-prolyl-tRNA synthetase (EPRS) have been found in many different eukaryotic tRNA synthetases and were previously shown to interact with another distinct repeated motifs in human isoleucyl-tRNA synthetase. Nuclear magnetic resonance and differential scanning calorimetry analyses of an isolated EPRS repeat showed that it consists of a helix-turn-helix with a melting temperature of 59 degrees C. Specific interaction of the EPRS repeats with those of isoleucyl-tRNA synthetase was confirmed by in vitro binding assays and shown to have a dissociation constant of approximately 2.9 microM. The EPRS repeats also showed the binding activity to the N-terminal motif of arginyl-tRNA synthetase as well as to various nucleic acids, including tRNA. Results of the present work suggest that the region comprising the repeated motifs of EPRS provides potential sites for interactions with various biological molecules and thus plays diverse roles in the cell.
Interacting selectively and non-covalently with a stem-loop in an RNA molecule. An RNA stem-loop is a secondary RNA structure consisting of a double-stranded RNA (dsRNA) stem and a terminal loop.
Aminoacyl tRNA synthetases (ARS) catalyze the ligation of amino acids to cognate tRNAs. Chordate ARSs have evolved distinctive features absent from ancestral forms, including compartmentalization in a multisynthetase complex (MSC), noncatalytic peptide appendages, and ancillary functions unrelated to aminoacylation. Here, we show that glutamyl-prolyl-tRNA synthetase (GluProRS), a bifunctional ARS of the MSC, has a regulated, noncanonical activity that blocks synthesis of a specific protein. GluProRS was identified as a component of the interferon (IFN)-gamma-activated inhibitor of translation (GAIT) complex by RNA affinity chromatography using the ceruloplasmin (Cp) GAIT element as ligand. In response to IFN-gamma, GluProRS is phosphorylated and released from the MSC, binds the Cp 3'-untranslated region in an mRNP containing three additional proteins, and silences Cp mRNA translation. Thus, GluProRS has divergent functions in protein synthesis: in the MSC, its aminoacylation activity supports global translation, but translocation of GluProRS to an inflammation-responsive mRNP causes gene-specific translational silencing.
Any process that results in a change in state or activity of a cell (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an interferon-gamma stimulus. Interferon-gamma is also known as type II interferon.
Aminoacyl tRNA synthetases (ARS) catalyze the ligation of amino acids to cognate tRNAs. Chordate ARSs have evolved distinctive features absent from ancestral forms, including compartmentalization in a multisynthetase complex (MSC), noncatalytic peptide appendages, and ancillary functions unrelated to aminoacylation. Here, we show that glutamyl-prolyl-tRNA synthetase (GluProRS), a bifunctional ARS of the MSC, has a regulated, noncanonical activity that blocks synthesis of a specific protein. GluProRS was identified as a component of the interferon (IFN)-gamma-activated inhibitor of translation (GAIT) complex by RNA affinity chromatography using the ceruloplasmin (Cp) GAIT element as ligand. In response to IFN-gamma, GluProRS is phosphorylated and released from the MSC, binds the Cp 3'-untranslated region in an mRNP containing three additional proteins, and silences Cp mRNA translation. Thus, GluProRS has divergent functions in protein synthesis: in the MSC, its aminoacylation activity supports global translation, but translocation of GluProRS to an inflammation-responsive mRNP causes gene-specific translational silencing.
The process of coupling glutamate to glutamyl-tRNA, catalyzed by glutamyl-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.
Any process that stops, prevents, or reduces the frequency, rate or extent of the chemical reactions and pathways resulting in the formation of proteins by the translation of mRNA.
Evidence
1:
Inferred from Mutant PhenotypeUniProtKB
Aminoacyl tRNA synthetases (ARS) catalyze the ligation of amino acids to cognate tRNAs. Chordate ARSs have evolved distinctive features absent from ancestral forms, including compartmentalization in a multisynthetase complex (MSC), noncatalytic peptide appendages, and ancillary functions unrelated to aminoacylation. Here, we show that glutamyl-prolyl-tRNA synthetase (GluProRS), a bifunctional ARS of the MSC, has a regulated, noncanonical activity that blocks synthesis of a specific protein. GluProRS was identified as a component of the interferon (IFN)-gamma-activated inhibitor of translation (GAIT) complex by RNA affinity chromatography using the ceruloplasmin (Cp) GAIT element as ligand. In response to IFN-gamma, GluProRS is phosphorylated and released from the MSC, binds the Cp 3'-untranslated region in an mRNP containing three additional proteins, and silences Cp mRNA translation. Thus, GluProRS has divergent functions in protein synthesis: in the MSC, its aminoacylation activity supports global translation, but translocation of GluProRS to an inflammation-responsive mRNP causes gene-specific translational silencing.
The gamma interferon (IFN-γ)-activated inhibitor of translation (GAIT) complex in human myeloid cells is heterotetrameric, consisting of glutamyl-prolyl-tRNA synthetase (EPRS), NS1-associated protein 1 (NSAP1), ribosomal protein L13a, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The complex binds a structural GAIT element in the 3' untranslated region of VEGF-A and other inflammation-related transcripts and inhibits their translation. EPRS is dually phosphorylated by cyclin-dependent kinase 5 (Cdk5) at Ser(886) and then by a Cdk5-dependent-AGC kinase at Ser(999); L13a is phosphorylated at Ser(77) by death-associated protein kinases DAPK and ZIPK. Because profound differences in inflammatory responses between mice and humans are known, we investigated the GAIT system in mouse macrophages. The murine GAIT complex is heterotrimeric, lacking NSAP1. As in humans, IFN-γ activates the mouse macrophage GAIT system via induced phosphorylation of EPRS and L13a. Murine L13a is phosphorylated at Ser(77) by the DAPK-ZIPK cascade, but EPRS is phosphorylated only at Ser(999). Loss of EPRS Ser(886) phosphorylation prevents NSAP1 incorporation into the GAIT complex. However, the triad of Ser(999)-phosphorylated EPRS, Ser(77)-phosphorylated L13a, and GAPDH forms a functional GAIT complex that inhibits translation of GAIT target mRNAs. Thus, translational control by the heterotrimeric GAIT complex in mice exemplifies the distinctive species-specific responses of myeloid cells to inflammatory stimuli.
The process of coupling proline to prolyl-tRNA, catalyzed by prolyl-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.
Glutamyl-tRNA synthetase and prolyl-tRNA synthetase belong to different classes of aminoacyl-tRNA synthetases that are thought to have evolved along independent evolutionary pathways. However, both enzymes are on one polypeptide chain encoded by a single human gene, the EPRS locus, which is transcribed as one long mRNA. We report the structure of the human EPRS gene, which consists of 29 exons spread over at least 90 kb of genomic DNA. The exons, encoding the glutamyl-specific and the prolyl-specific parts of the enzyme, are each clustered in 10-kb sections located at opposite ends of the gene. These two exon clusters are separated by a long intervening DNA section with a number of exons, encoding functions that may be involved in the organization of the mammalian multienzyme synthetase complex. The upstream gene region shows structural features of a regulated gene, and preliminary experiments suggest that the gene is expressed at specific times in growth-stimulated cultured cells. We have localized the gene to the distal long arm of human chromosome 1 and to a corresponding site in mouse chromosome 1.
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.
My favorites 
My labels 
Login
