Summary: tRNA synthetases class I (E and Q), catalytic domain
This is the Wikipedia entry entitled "Aminoacyl tRNA synthetases, class I". More...
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Aminoacyl tRNA synthetases, class I Edit Wikipedia article
|Glutamyl/glutaminyl-tRNA synthetase, class Ic|
The aminoacyl-tRNA synthetases (EC 6.1.1.) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have limited sequence homology. The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossman fold catalytic domain and are mostly monomeric. Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices, and are mostly dimeric or multimeric, containing at least three conserved regions. However, tRNA binding involves an alpha-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan and valine belong to class I synthetases; these synthetases are further divided into three subclasses, a, b and c, according to sequence homology. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, phenylalanine, proline, serine, and threonine belong to class-II synthetases.
Glutamyl-tRNA synthetase (EC 18.104.22.168) is a class Ic synthetase and shows several similarities with glutaminyl-tRNA synthetase concerning structure and catalytic properties. It is an alpha2 dimer. To date one crystal structure of a glutamyl-tRNA synthetase (Thermus thermophilus) has been solved. The molecule has the form of a bent cylinder and consists of four domains. The N-terminal half (domains 1 and 2) contains the 'Rossman fold' typical for class I synthetases and resembles the corresponding part of E. coli GlnRS, whereas the C-terminal half exhibits a GluRS-specific structure.
Human proteins containing this domain
- Delarue M, Moras D, Poch O, Eriani G, Gangloff J (1990). "Partition of tRNA synthetases into two classes based on mutually exclusive sets of sequence motifs". Nature 347 (6289): 203–206. doi:10.1038/347203a0. PMID 2203971.
- Moras D, Konno M, Shimada A, Nureki O, Tateno M, Yokoyama S, Sugiura I, Ugaji-Yoshikawa Y, Kuwabara S, Lorber B, Giege R (2000). "The 2.0 A crystal structure of Thermus thermophilus methionyl-tRNA synthetase reveals two RNA-binding modules". Structure 8 (2): 197–208. doi:10.1016/S0969-2126(00)00095-2. PMID 10673435.
- Perona JJ, Steitz TA, Rould MA (1993). "Structural basis for transfer RNA aminoacylation by Escherichia coli glutaminyl-tRNA synthetase". Biochemistry 32 (34): 8758–8771. doi:10.1021/bi00085a006. PMID 8364025.
- Delarue M, Moras D (1993). "The aminoacyl-tRNA synthetase family: modules at work". BioEssays 15 (10): 675–687. doi:10.1002/bies.950151007. PMID 8274143.
- Schimmel P (1991). "Classes of aminoacyl-tRNA synthetases and the establishment of the genetic code". Trends Biochem. Sci. 16 (1): 1–3. doi:10.1016/0968-0004(91)90002-D. PMID 2053131.
- Cusack S, Leberman R, Hartlein M (1991). "Sequence, structural and evolutionary relationships between class 2 aminoacyl-tRNA synthetases". Nucleic Acids Res. 19 (13): 3489–3498. doi:10.1093/nar/19.13.3489. PMC 328370. PMID 1852601.
- Bairoch A (2004). List of aminoacyl-tRNA synthetases. pp. –.
- Soll D, Freist W, Gauss DH, Lapointe J (1997). "Glutamyl-tRNA sythetase". Biol. Chem. 378 (11): 1313–1329. PMID 9426192.
tRNA synthetases class I (E and Q), catalytic domain Provide feedback
Other tRNA synthetase sub-families are too dissimilar to be included. This family includes only glutamyl and glutaminyl tRNA synthetases. In some organisms, a single glutamyl-tRNA synthetase aminoacylates both tRNA(Glu) and tRNA(Gln).
Internal database links
|Similarity to PfamA using HHSearch:||tRNA-synt_1e tRNA-synt_1f tRNA-synt_1g|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR020058
The aminoacyl-tRNA synthetases (EC) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have limited sequence homology [PUBMED:2203971]. The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossman fold catalytic domain and are mostly monomeric [PUBMED:10673435]. Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices [PUBMED:8364025], and are mostly dimeric or multimeric, containing at least three conserved regions [PUBMED:8274143, PUBMED:2053131, PUBMED:1852601]. However, tRNA binding involves an alpha-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan and valine belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, phenylalanine, proline, serine, and threonine belong to class-II synthetases [PUBMED:]. Based on their mode of binding to the tRNA acceptor stem, both classes of tRNA synthetases have been subdivided into three subclasses, designated 1a, 1b, 1c and 2a, 2b, 2c.
Glutamyl-tRNA synthetase (EC) is a class Ic synthetase and shows several similarities with glutaminyl-tRNA synthetase concerning structure and catalytic properties. It is an alpha2 dimer. To date one crystal structure of a glutamyl-tRNA synthetase (Thermus thermophilus) has been solved. The molecule has the form of a bent cylinder and consists of four domains. The N-terminal half (domains 1 and 2) contains the 'Rossman fold' typical for class I synthetases and resembles the corresponding part of Escherichia coli GlnRS, whereas the C-terminal half exhibits a GluRS-specific structure [PUBMED:9426192].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||cytoplasm (GO:0005737)|
|Molecular function||ligase activity, forming aminoacyl-tRNA and related compounds (GO:0016876)|
|ATP binding (GO:0005524)|
|nucleotide binding (GO:0000166)|
|Biological process||tRNA aminoacylation (GO:0043039)|
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The HUP class contains the HIGH-signature proteins, UspA superfamily and the PP-ATPase superfamily . The HIGH superfamily has the HIGH Nucleotidyl transferases and the class I tRNA synthetases both of which have the HIGH and the KMSKS motif ,. The PP-loop ATPase named after the ATP PyroPhosphatase domain, was initially identified as a conserved amino acid sequence motif in four distinct groups of enzymes that catalyse the hydrolysis of the alpha-beta phosphate bond of ATP, namely GMP synthetases, argininosuccinate synthetases, asparagine synthetases, and ATP sulfurylases . The USPA superfamily contains USPA, ETFP and Photolyases 
The clan contains the following 26 members:Arginosuc_synth Asn_synthase ATP-sulfurylase ATP_bind_3 ATP_bind_4 Citrate_ly_lig CTP_transf_2 DNA_photolyase ETF FAD_syn HIGH_NTase1 NAD_synthase Pantoate_ligase PAPS_reduct QueC ThiI tRNA-synt_1 tRNA-synt_1_2 tRNA-synt_1b tRNA-synt_1c tRNA-synt_1d tRNA-synt_1e tRNA-synt_1f tRNA-synt_1g tRNA_Me_trans Usp
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Curation and family details
|Seed source:||Pfam-B_350 (release 2.1)|
|Author:||Bateman A, Griffiths-Jones SR|
|Number in seed:||18|
|Number in full:||10836|
|Average length of the domain:||287.60 aa|
|Average identity of full alignment:||31 %|
|Average coverage of the sequence by the domain:||62.06 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||16|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the tRNA-synt_1c domain has been found. There are 51 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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