Aminoacyl tRNA synthetase - wikipedia Aminoacyl tRNA synthetase Anticodon - binding domain of tRNA leucyl - tRNA synthetase from Thermus thermophilus complexed with a post-transfer editing substrate analogue Identifiers Symbol Anticodon_2 Pfam PF08264 InterPro IPR013155 SCOP 1ivs SUPERFAMILY 1ivs Available protein structures : Pfam structures PDB RCSB PDB ; PDBe ; PDBj PDBsum structure summary DALR anticodon binding domain 1 Thermus thermophilus arginyl - trna synthetase Identifiers Symbol DALR_1 Pfam PF05746 Pfam clan CL0258 InterPro IPR008909 SCOP 1bs2 SUPERFAMILY 1bs2 Available protein structures : Pfam structures PDB RCSB PDB ; PDBe ; PDBj PDBsum structure summary DALR anticodon binding domain 2 crystal structure of cysteinyl - tRNA synthetase binary complex with tRNA Identifiers Symbol DALR_2 Pfam PF09190 Pfam clan CL0258 InterPro IPR015273 Available protein structures : Pfam structures PDB RCSB PDB ; PDBe ; PDBj PDBsum structure summary An aminoacyl tRNA synthetase ( aaRS ) is an enzyme that attaches the appropriate amino acid onto its tRNA. It does so by catalyzing the esterification of a specific cognate amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl - tRNA. In humans, the 21 different types of aa - tRNA are made by the 21 different aminoacyl - tRNA synthetases, one for each amino acid of the genetic code. This is sometimes called `` charging '' or `` loading '' the tRNA with the amino acid. Once the tRNA is charged, a ribosome can transfer the amino acid from the tRNA onto a growing peptide, according to the genetic code. Aminoacyl tRNA therefore plays an important role in RNA translation, the expression of genes to create proteins. As genetic efficiency evolved in higher organisms, 13 new domains with no obvious association with the catalytic activity of aaRSs genes have been added. Contents 1 Mechanism 2 Classes 3 Structures 4 Evolution 5 Application in biotechnology 6 Noncatalytic domains 7 Prediction Servers 8 See also 9 References 10 External links Mechanism The synthetase first binds ATP and the corresponding amino acid ( or its precursor ) to form an aminoacyl - adenylate, releasing inorganic pyrophosphate ( PP ). The adenylate - aaRS complex then binds the appropriate tRNA molecule 's D arm, and the amino acid is transferred from the aa - AMP to either the 2 ' - or the 3 ' - OH of the last tRNA nucleotide ( A76 ) at the 3 ' - end. The mechanism can be summarized in the following reaction series : Amino Acid + ATP → Aminoacyl - AMP + PP Aminoacyl - AMP + tRNA → Aminoacyl - tRNA + AMP Summing the reactions, the highly exergonic overall reaction is as follows : Amino Acid + tRNA + ATP → Aminoacyl - tRNA + AMP + PP Some synthetases also mediate a editing reaction to ensure high fidelity of tRNA charging. If the incorrect tRNA is added ( aka. the tRNA is found to be improperly charged ), the aminoacyl - tRNA bond is hydrolyzed. This can happen when two amino acids have different properties even if they have similar shapes -- as is the case with Valine and Threonine. Classes There are two classes of aminoacyl tRNA synthetase : Class I has two highly conserved sequence motifs. It aminoacylates at the 2 ' - OH of a terminal adenosine nucleotide on tRNA, and it is usually monomeric or dimeric ( one or two subunits, respectively ). Class II has three highly conserved sequence motifs. It aminoacylates at the 3 ' - OH of a terminal adenosine on tRNA, and is usually dimeric or tetrameric ( two or four subunits, respectively ). Although phenylalanine - tRNA synthetase is class II, it aminoacylates at the 2 ' - OH. The amino acids are attached to the hydroxyl ( - OH ) group of the adenosine via the carboxyl ( - COOH ) group. Regardless of where the aminoacyl is initially attached to the nucleotide, the 2 ' - O - aminoacyl - tRNA will ultimately migrate to the 3 ' position via transesterification. Structures Both classes of aminoacyl - tRNA synthetases are multidomain proteins. In a typical scenario, an aaRS consists of a catalytic domain ( where both the above reactions take place ) and an anticodon binding domain ( which interacts mostly with the anticodon region of the tRNA and ensures binding of the correct tRNA to the amino acid ). In addition, some aaRSs have additional RNA binding domains and editing domains that cleave incorrectly paired aminoacyl - tRNA molecules. The catalytic domains of all the aaRSs of a given class are found to be homologous to one another, whereas class I and class II aaRSs are unrelated to one another. The class I aaRSs have the ubiquitous Rossmann fold and have the parallel beta - strands architecture, whereas the class II aaRSs have a unique fold made up of antiparallel beta - strands. The alpha helical anticodon binding domain of Arginyl, Glycyl and Cysteinyl - tRNA synthetases is known as the DALR domain after characteristic conserved amino acids. Evolution Most of the aaRSs of a given specificity are evolutionarily closer to one another than to aaRSs of another specificity. However, AsnRS and GlnRS group within AspRS and GluRS, respectively. Most of the aaRSs of a given specificity also belong to a single class. However, there are two distinct versions of the LysRS - one belonging to the class I family and the other belonging to the class II family. The molecular phylogenies of aaRSs are often not consistent with accepted organismal phylogenies. That is, they violate the so - called canonical phylogenetic pattern shown by most other enzymes for the three domains of life - Archaea, Bacteria, and Eukarya. Furthermore, the phylogenies inferred for aaRSs of different amino acids often do not agree with one another. In addition, aaRS paralogs within the same species show a high degree of divergence between them. These are clear indications that horizontal transfer has occurred several times during the evolutionary history of aaRSs. A widespread belief in the evolutionary stability of this superfamily, meaning that every organism has all the aaRSs for their corresponding aminoacids is misconceived. A large - scale genomic analysis on ~ 2500 prokaryotic genomes showed that many of them miss one or more aaRS genes whereas many genomes have 1 or more paralogs. AlaRS, GlyRS, LeuRS, IleRS and ValRS are the most evolutionarily stable members of the family. GluRS, LysRS and CysRS often have paralogs, whereas AsnRS, GlnRS, PylRS and SepRS are often absent from many genomes. Application in biotechnology In some of the aminoacyl tRNA synthetases, the cavity that holds the amino acid can be mutated and modified to carry unnatural amino acids synthesized in the lab, and to attach them to specific tRNAs. This expands the genetic code, beyond the twenty canonical amino acids found in nature, to include an unnatural amino acid as well. The unnatural amino acid is coded by a nonsense ( TAG, TGA, TAA ), quadruplet, or in some cases a redundant rare codon. The organism that expresses the mutant synthetase can then be genetically programmed to incorporate the unnatural amino acid into any desired position in any protein of interest, allowing biochemists or structural biologists to probe or change the protein 's function. For instance, one can start with the gene for a protein that binds a certain sequence of DNA, and, by directing an unnatural amino acid with a reactive side - chain into the binding site, create a new protein that cuts the DNA at the target - sequence, rather than binding it. By mutating aminoacyl tRNA synthetases, chemists have expanded the genetic codes of various organisms to include lab - synthesized amino acids with all kinds of useful properties : photoreactive, metal - chelating, xenon - chelating, crosslinking, spin - resonant, fluorescent, biotinylated, and redox - active amino acids. Another use is introducing amino acids bearing reactive functional groups for chemically modifying the target protein. Non-catalytic domains The novel domain additions to aaRS genes are accretive and progressive up the Tree of Life. The strong evolutionary pressure for these small non-catalytic protein domains suggested their importance. Findings beginning in 1999 and later revealed a previously unrecognized layer of biology : these proteins control gene expression within the cell of origin, and when released exert homeostatic and developmental control in specific human cell types, tissues and organs during adult or fetal development or both, including pathways associated with angiogenesis, inflammation, the immune response, the mechanistic target of rapamycin ( mTOR ) signalling, apoptosis, tumorigenesis, and interferon gamma ( IFN - γ ) and p53 signalling. Prediction servers ICAARS : B. Pawar, and GPS Raghava ( 2010 ) Prediction and classification of aminoacyl tRNA synthetases using PROSITE domains. BMC Genomics 2010, 11 : 507 MARSpred : Pawar, B. ; Raghava, GPS ( 2011 ). `` Predicting sub-cellular localization of tRNA synthetases from their primary structures ''. Amino Acids. 42 ( 5 ) : 1703 -- 13. doi : 10.1007 / s00726 - 011 - 0872 - 8. PMID 21400228. Prokaryotic AARS database : Chaliotis et al., ( 2017 ). The complex evolutionary history of aminoacyl - tRNA synthetases. Nucleic Acids Res. 2017 Feb 17 ; 45 ( 3 ) : 1059 - 1068. doi : 10.1093 / nar / gkw1182. See also TARS ( gene ) References Jump up ^ `` tRNA Synthetases ''. Retrieved 2007 - 08 - 18. Jump up ^ `` Molecule of the Month : Aminoacyl - tRNA Synthetases High Fidelity ''. Retrieved 2013 - 08 - 04. Jump up ^ Wolf YI, Aravind L, Grishin NV, Koonin EV ( August 1999 ). `` Evolution of aminoacyl - tRNA synthetases -- analysis of unique domain architectures and phylogenetic trees reveals a complex history of horizontal gene transfer events ''. Genome Res. 9 ( 8 ) : 689 -- 710. doi : 10.1101 / gr. 9.8. 689. PMID 10447505. Jump up ^ Woese, CR ; Olsen, GJ ; Ibba, M ; Söll, D ( March 2000 ). `` Aminoacyl - tRNA synthetases, the genetic code, and the evolutionary process ''. Microbiology and molecular biology reviews : MMBR. 64 ( 1 ) : 202 -- 36. doi : 10.1128 / MMBR. 64.1. 202 - 236.2000. PMC 98992. PMID 10704480. ^ Jump up to : Chaliotis, Anargyros ; Vlastaridis, Panayotis ; Mossialos, Dimitris ; Ibba, Michael ; Becker, Hubert D. ; Stathopoulos, Constantinos ; Amoutzias, Grigorios D. ( 2017 - 02 - 17 ). `` The complex evolutionary history of aminoacyl - tRNA synthetases ''. Nucleic Acids Research. 45 ( 3 ) : 1059 -- 1068. doi : 10.1093 / nar / gkw1182. ISSN 0305 - 1048. PMC 5388404. PMID 28180287. Jump up ^ Peter G. Schultz, Expanding the genetic code Jump up ^ Ludmerer, SW ; Schimmel, P ( August 5, 1987 ). `` Construction and analysis of deletions in the amino - terminal extension of glutamine tRNA synthetase of Saccharomyces cerevisiae ''. Journal of Biological Chemistry : JBC. 262 ( 22 ) : 10807 -- 10813. PMID 3301842. Jump up ^ Eriani, Gilbert ; Delarue, M ( Sep 13, 1990 ). `` Partition of tNRA Synthetases into Two Classes Based on Mutually Exclusive Sets of Sequence Motifs ''. Nature. 347 ( 6289 ) : 203 -- 206. doi : 10.1038 / 347203a0. PMID 2203971. Jump up ^ Cusack, S ( Dec 1, 1997 ). `` Aminoacyl - tRNA synthetases ''. Curr Opin Struct Biol. 7 ( 6 ) : 881 -- 889. PMID 9434910. Jump up ^ Lo, Wing - Sze ; Gardiner, E ( July 18, 2014 ). `` Human tRNA Synthetase Catalytic Nulls with Diverse Functions ''. Nature. 345 ( 6194 ) : 328 -- 332. doi : 10.1126 / science. 1252943. Jump up ^ Wakasugi ; Schimmel, P ( April 2, 1999 ). `` Two Distinct Cytokines Released from a Human Aminoacyl - tRNA Synthetase ''. Science. 284 ( 5411 ) : 147 -- 151. doi : 10.1126 / science. 284.5411. 147. Jump up ^ Lareau, LF ; Green, RE ( June 1, 2004 ). `` The evolving roles of alternative splicing ''. Current Opinion in Structural Biology. 14 ( 3 ) : 273 -- 282. doi : 10.1016 / j. sbi. 2004.05. 002. Jump up ^ Wakasugi, K ; Slike, BM ( Jan 8, 2002 ). `` A human aminoacyl - tRNA synthetase as a regulator of angiogenesis ''. 99 ( 1 ) : 173 -- 177. doi : 10.1073 / pnas. 012602099. Jump up ^ Tzima, E ; Reader, JS ( Dec 3, 2004 ). `` VE - cadherin Links tRNA Synthetase Cytokine to Anti-angiogenic Function ''. 280 : 2405 -- 2408. doi : 10.1074 / jbc. C400431200. Jump up ^ Kawahara, A ; Didier, YR ( August 2009 ). `` Noncanonical Activity of Seryl - Transfer RNA Synthetase and Vascular Development ''. Trends in Cardiovascular Medicine. 19 ( 6 ) : 179 -- 182. doi : 10.1016 / j. tcm. 2009.11. 001. Jump up ^ Zhou, Q ; Kapoor, M ( Jan 2010 ). `` Orthogonal use of a human tRNA synthetase active site to achieve multifunctionality ''. Nature Structural & Molecular Biology. 17 ( 1 ) : 57 -- 61. doi : 10.1038 / nsmb. 1706. Jump up ^ Park, SG ; Hye, JK ( May 3, 2005 ). `` Human lysyl - tRNA synthetase is secreted to trigger proinflammatory response ''. PNAS. 102 ( 18 ) : 6356 -- 6361. doi : 10.1073 / pnas. 0500226102. Jump up ^ Arif, A ; Jai, J ( Jan 25, 2011 ). `` Phosphorylation of glutamyl - prolyl tRNA synthetase by cyclin - dependent kinase 5 dictates transcript - selective translational control ''. PNAS. 108 ( 4 ) : 1415 -- 1420. doi : 10.1073 / pnas. 1011275108. Jump up ^ Guo, M ; Schimmel, P ( March 2013 ). `` Essential nontranslational functions of tRNA synthetases ''. Nat Chem Biol. 9 ( 3 ) : 145 -- 153. doi : 10.1038 / nchembio. 1158. External Links Amino Acyl - tRNA Synthetases at the US National Library of Medicine Medical Subject Headings ( MeSH ) AARS human gene location in the UCSC Genome Browser. AARS human gene details in the UCSC Genome Browser. This article incorporates text from the public domain Pfam and InterPro IPR015273 This article incorporates text from the public domain Pfam and InterPro IPR008909 Protein biosynthesis : translation ( prokaryotic, eukaryotic ) Proteins Initiation factor Prokaryotic PIF - 1 PIF - 2 PIF - 3 Archaeal aIF1 aIF2 aIF5 aIF6 Eukaryotic eIF1 eIF1 EIF1AX AY 1B eIF2 EIF2S1 EIF2S2 EIF2S3 EIF2B1 EIF2B2 EIF2B3 EIF2B4 EIF2B5 EIF - 2 kinase eIF2A eIF2D eIF3 EIF3A eIF4 EIF4A2 A3 E1 E2 E3 G1 G2 G3 eIF5 EIF5 EIF5A A2 5B eIF6 EIF6 Elongation factor Prokaryotic EF - Tu EF - Ts EF - G Archaeal aEF - 1 aEF - 2 Eukaryotic EEF - 1 EEF1A1 EEF1A2 EEF1A3 EEF1B1 EEF1B2 EEF1B3 EEF1B4 EEF1D EEF1E1 EEF1G EEF2 Release factor Prokaryotic Archaeal Eukaryotic ( ETF1 ) Ribosomal Proteins Cytoplasmic 60S subunit RPL3 RPL4 RPL5 RPL6 RPL7 RPL7A RPL8 RPL9 RPL10 RPL10A RPL10 - like RPL11 RPL12 RPL13 RPL13A RPL14 RPL15 RPL16 RPL17 RPL18 RPL18A RPL19 RPL20 RPL21 RPL22 RPL23 RPL23A RPL24 RPL25 RPL26 RPL27 RPL27A RPL28 RPL29 RPL30 RPL31 RPL32 RPL33 RPL34 RPL35 RPL35A RPL36 RPL36A RPL37 RPL37A RPL38 RPL39 RPL40 RPL41 RPLP0 RPLP1 RPLP2 RPLP3 RRP15 - like RSL24D1 40S subunit RPSA RPS2 RPS3 RPS3A RPS4 ( RPS4X, RPS4Y1, RPS4Y2 ) RPS5 RPS6 RPS7 RPS8 RPS9 RPS10 RPS11 RPS12 RPS13 RPS14 RPS15 RPS15A RPS16 RPS17 RPS18 RPS19 RPS20 RPS21 RPS22 RPS23 RPS24 RPS25 RPS26 RPS27 RPS27A RPS28 RPS29 RPS30 RACK1 Mitochondrial 39S subunit MRPL1 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 28S subunit MRPS1 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Other concepts Aminoacyl tRNA synthetase Reading frame Start codon Stop codon Shine - Dalgarno sequence / Kozak consensus sequence Enzymes : CO CS and CN ligases ( EC 6.1 - 6.3 ) 6.1 : Carbon - Oxygen Aminoacyl tRNA synthetase Alanine Arginine Asparagine Aspartate Cysteine D - alanine -- poly ( phosphoribitol ) ligase Glutamate Glutamine Glycine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Proline Serine Threonine Tryptophan Tyrosine Valine 6.2 : Carbon - Sulfur Succinyl coenzyme A synthetase Acetyl -- CoA synthetase Long - chain - fatty - acid -- CoA ligase 6.3 : Carbon - Nitrogen Glutamine synthetase Ubiquitin ligase Cullin Von Hippel -- Lindau tumor suppressor UBE3A Mdm2 Anaphase - promoting complex UBR1 Glutathione synthetase CTP synthetase Adenylosuccinate synthase Argininosuccinate synthase Holocarboxylase synthetase GMP synthase Asparagine synthetase Carbamoyl phosphate synthetase II Glutamate -- cysteine ligase Ligases : carbon - carbon ligases ( EC 6.4 ) Biotin dependent carboxylation Pyruvate carboxylase Acetyl - CoA carboxylase Propionyl - CoA carboxylase Methylcrotonyl - CoA carboxylase Other Polyketide synthase Enzymes : Phosphoric ester and nitrogen - metal ligases ( EC 6.5 - 6.6 ) 6.5 : Phosphoric Ester DNA ligase 6.6 : Nitrogen - Metal Magnesium chelatase Cobalt chelatase Enzymes Activity Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Regulation Allosteric regulation Cooperativity Enzyme inhibitor Classification EC number Enzyme superfamily Enzyme family List of enzymes Kinetics Enzyme kinetics Eadie -- Hofstee diagram Hanes -- Woolf plot Lineweaver -- Burk plot Michaelis -- Menten kinetics Types EC1 Oxidoreductases ( list ) EC2 Transferases ( list ) EC3 Hydrolases ( list ) EC4 Lyases ( list ) EC5 Isomerases ( list ) EC6 Ligases ( list ) Molecular and Cellular Biology portal Retrieved from `` https://en.wikipedia.org/w/index.php?title=Aminoacyl_tRNA_synthetase&oldid=800858861 '' Categories : EC 6.1 Protein biosynthesis Talk Contents About Wikipedia Bosanski Català Čeština Deutsch Eesti Español Français Galego 한국어 Italiano Nederlands 日本 語 Português Русский Українська 中文 Edit links This page was last edited on 16 September 2017, at 03 : 14. 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Question: where is the amino-acid binding site located on the trna molecule
Answer: 21 different types of aa-tRNA are made by the 21 different aminoacyl-tRNA synthetases, one for each amino acid of the genetic code