Summary: tRNA synthetases class I (K)
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tRNA synthetases class I (K) Provide feedback
This family includes only lysyl tRNA synthetases from prokaryotes.
Ibba M, Morgan S, Curnow AW, Pridmore DR, Vothknecht UC, Gardner W, Lin W, Woese CR, Soll D; , Science 1997;278:1119-1122.: A euryarchaeal lysyl-tRNA synthetase: resemblance to class I synthetases. PUBMED:9353192 EPMC:9353192
Internal database links
|Similarity to PfamA using HHSearch:||tRNA-synt_1b tRNA-synt_1 tRNA-synt_1c tRNA-synt_1e tRNA-synt_1g|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR002904
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.
Lysyl-tRNA synthetase (EC) is an alpha 2 homodimer that belong to both class I and class II. In eubacteria and eukaryota lysyl-tRNA synthetases belong to class II in the same family as aspartyl tRNA synthetase. The class Ic lysyl-tRNA synthetase family is present in archaea and in a number of bacterial groups that include the alphaproteobacteria and spirochaetes[PUBMED:9353192]. A refined crystal structures shows that the active site of LysU is shaped to position the substrates for the nucleophilic attack of the lysine carboxylate on the ATP alpha-phosphate. No residues are directly involved in catalysis, but a number of highly conserved amino acids and three metal ions coordinate the substrates and stabilise the pentavalent transition state. A loop close to the catalytic pocket, disordered in the lysine-bound structure, becomes ordered upon adenine binding [PUBMED:10913247].
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||ATP binding (GO:0005524)|
|nucleotide binding (GO:0000166)|
|lysine-tRNA ligase activity (GO:0004824)|
|Biological process||lysyl-tRNA aminoacylation (GO:0006430)|
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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:||Enright A|
|Author:||Enright A, Ouzounis C, Bateman A|
|Number in seed:||39|
|Number in full:||631|
|Average length of the domain:||353.70 aa|
|Average identity of full alignment:||38 %|
|Average coverage of the sequence by the domain:||66.72 %|
|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:||13|
|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_1f domain has been found. There are 2 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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