SII-SWORD/CoKE huggingface dataset:
Tyrosine-tRNA ligase (Tyr-tRNA-ligase)
Type: Family

Tyrosine-tRNA ligases (TyrRS; also known as Tyrosyl-tRNA synthetases) (

) are widely distributed, being found in archaea, bacteria and eukaryotes. TyrRS is a homodimer which attaches Tyr to the appropriate tRNA. TyrRS is a class I tRNA synthetases, so it aminoacylates the 2'-OH of the nucleotide at the 3' end of the tRNA. The core domain is based on the Rossman fold and is responsible for the ATP-dependent formation of the enzyme bound aminoacyl-adenylate. It contains the class I characteristic 'HIGH' and 'KMSKS' motifs, which are involved in ATP binding. Studies have shown that the 'KMSKS' motif plays a role in the initial binding of tRNA(Tyr) to tyrosine-tRNA ligase .

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .

The class Ia aminoacyl-tRNA synthetases consist of the isoleucyl, methionyl, valyl, leucyl, cysteinyl, and arginyl-tRNA synthetases; the class Ib include the glutamyl and glutaminyl-tRNA synthetases, and the class Ic are the tyrosyl and tryptophanyl-tRNA synthetases .
Glycine-tRNA ligase, alpha subunit (Gly-tRNA_ligase_asu)
Type: Family

This entry represents the alpha subunit of glycine-tRNA ligase (also known as glycyl-tRNA synthetase alpha subunit). It is responsible for the attachment of glycine to the 3' OH group of ribose of the appropriate tRNA. This domain is primarily responsible for the ATP-dependent formation of the enzyme bound aminoacyl-adenylate.

In eubacteria, glycine-tRNA ligase (

) is an alpha2/beta2 tetramer composed of 2 different subunits . In some eubacteria, in archaea and eukaryota, glycine-tRNA ligase is an alpha2 dimer (see

). It belongs to class IIc and is one of the most complex ligases. What is most interesting is the lack of similarity between the two types: divergence at the sequence level is so great that it is impossible to infer descent from common genes. The alpha and beta subunits also lack significant sequence similarity. However, they are translated from a single mRNA , and a single chain glycine-tRNA ligase from Chlamydia trachomatis has been found to have significant similarity with both domains, suggesting divergence from a single polypeptide chain .

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .
Aspartyl/Asparaginyl-tRNA synthetase, class IIb (Asp/Asn-tRNA-synth_IIb)
Type: Family

Aspartyl tRNA synthetase

is an alpha2 dimer that belongs to class IIb. Structural analysis combined with mutagenesis and enzymology data on the yeast enzyme point to a tRNA binding process that starts by a recognition event between the tRNA anticodon loop and the synthetase anticodon binding module .

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .
Lysine-tRNA ligase, class II (Lys-tRNA-ligase_II)
Type: Family

This entry represents lysine-tRNA ligase class II.

Lysine-tRNA synthesis is catalysed by two unrelated families of tRNA ligases: class-I or class-II. In eubacteria and eukaryota lysine-tRNA ligases belong to class II, the same family as aspartyl tRNA ligase. The lysine-tRNA ligase class Ic family is present in archaea and some eubacteria . Moreover in some eubacteria there is a gene X, which is similar to a part of lysine-tRNA ligase from class II.

Lysine-tRNA ligase is duplicated in some species with, for example in Escherichia coli, as a constitutive gene (lysS) and an induced one (lysU). 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. Lysine is activated by being attached to the alpha-phosphate of AMP before being transferred to the cognate tRNA. The refined crystal structures give "snapshots" of the active site corresponding to key steps in the aminoacylation reaction and provide the structural framework for understanding the mechanism of lysine activation. 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 .

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .
Aminoacyl-tRNA synthetase, class II (G/ P/ S/T) (aa-tRNA-synt_IIb)
Type: Domain

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .

This domain is the core catalytic domain of tRNA synthetases and includes glycyl, prolyl, seryl and threonyl tRNA synthetases.
Glycyl-tRNA synthetase (tRNA-synt_gly)
Type: Family

In eubacteria, glycine-tRNA ligase (

) is an alpha2/beta2 tetramer composed of 2 different subunits . In some eubacteria, in archaea and eukaryotes, glycine-tRNA ligase is an alpha2 dimer, this family. It belongs to class IIc and is one of the most complex ligases. What is most interesting is the lack of similarity between the two types: divergence at the sequence level is so great that it is impossible to infer descent from common genes. The alpha (see

) and beta subunits (see

) also lack significant sequence similarity. However, they are translated from a single mRNA , and a single chain glycine-tRNA ligase from Chlamydia trachomatis has been found to have significant similarity with both domains, suggesting divergence from a single polypeptide chain .

The sequence and crystal structure of the homodimeric glycine-tRNA ligase from Thermus thermophilus, shows that each monomer consists of an active site strongly resembling that of the aspartyl and seryl enzymes, a C-terminal anticodon recognition domain of 100 residues and a third domain unusually inserted between motifs 1 and 2 almost certainly interacting with the acceptor arm of tRNA(Gly). The C-terminal domain has a novel five-stranded parallel-antiparallel β-sheet structure with three surrounding helices. The active site residues most probably responsible for substrate recognition, in particular in the Gly binding pocket, can be identified by inference from aspartyl-tRNA ligase due to the conserved nature of the class II active site .

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .
Proline-tRNA ligase, class IIa (Pro-tRNA-ligase_IIa)
Type: Family

Proline-tRNA ligase (also known as Prolyl-tRNA synthetase) belongs to class IIa aminoacyl-tRNA synthetases. Prolyl-tRNA synthetase (

) exists in two forms, which are loosely related. The first form is present in the majority of eubacteria species. The second one, present in some eubacteria, is essentially present in archaea and eukaryota. The enzyme from Escherichia coli contains all three of the conserved consensus motifs characteristic of class II aminoacyl-tRNA synthetases . The complex between Thermus thermophilus prolyl-tRNA synthetase (ProRSTT) and its cognate tRNA has been crystallized using two different isoacceptors of tRNA(Pro) .

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .
Serine-tRNA ligase, type1 (Ser-tRNA-ligase_type_1)
Type: Family

Serine-tRNA ligase (

) exists as monomer and belongs to the aminoacyl-tRNA synthetase class IIa . It catalyses the attachment of serine to tRNA (Ser). It is also able to aminoacylate tRNA (Sec) with serine, to form the misacylated tRNA L-seryl-tRNA (Sec), which will be further converted into selenocysteinyl-tRNA (Sec).

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .
Alanine-tRNA ligase, class IIc (Ala-tRNA-lgiase_IIc)
Type: Family

Alanine-tRNA ligase (also known as alanyl-tRNA synthetase) (

) is an alpha4 tetramer that belongs to class IIc.

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .
Phenylalanyl-tRNA synthetase (Phenylalanyl-tRNA_Synthase)
Type: Domain

The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) 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 β-sheet fold flanked by α-helices , and are mostly dimeric or multimeric, containing at least three conserved regions . However, tRNA binding involves an α-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, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. 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 .

Phenylalanyl-tRNA synthetase (

) is an alpha2/beta2 tetramer composed of 2 subunits that belongs to class IIc. In eubacteria, a small subunit (pheS gene) can be designated as beta (E. coli) or alpha subunit (nomenclature adopted in InterPro). Reciprocally the large subunit
(pheT gene) can be designated as alpha (E. coli) or beta (see

and

). In all other kingdoms the two subunits have equivalent length in eukaryota, and can be identified by specific signatures. The enzyme from Thermus thermophilus has an alpha 2 beta 2 type quaternary structure and is one of the most complicated members of the synthetase family. Identification of phenylalanyl-tRNA synthetase as a member of class II aaRSs was based only on sequence alignment of the small alpha-subunit with other synthetases .