Description

IPR017932 is a Glutamine amidotransferase type 2 domain.

<p>A large group of biosynthetic enzymes are able to catalyse the removal of the ammonia group from glutamine and then to transfer this group to a substrate to form a new carbon-nitrogen group. This catalytic activity is known as glutamine amidotransferase (GATase) [[cite:PUB00000003]]. The GATase domain exists either as a separate polypeptidic subunit or as part of a larger polypeptide fused in different ways to a synthase domain. On the basis of sequence similarities two classes of GATase domains have been identified [[cite:PUB00002062], [cite:PUB00002406]]: class-I (also known as trpG-type or triad) and class-II (also known as purF-type or Ntn). Class-II (or type 2) GATase domains have been found in the following enzymes:</p> <ul> <li>Amido phosphoribosyltransferase (glutamine phosphoribosylpyrophosphate amidotransferase). An enzyme which catalyses the first step in purine biosynthesis, the transfer of the ammonia group of glutamine to PRPP to form 5-phosphoribosylamine (gene purF in bacteria, ADE4 in yeast).</li> <li>Glucosamine--fructose-6-phosphate aminotransferase. This enzyme catalyses a key reaction in amino sugar synthesis, the formation of glucosamine 6-phosphate from fructose 6-phosphate and glutamine (gene glmS in Escherichia coli, nodM in Rhizobium, GFA1 in yeast).</li> <li>Asparagine synthetase (glutamine-hydrolyzing). This enzyme is responsible for the synthesis of asparagine from aspartate and glutamine.</li> <li>Glutamate synthase (gltS), an enzyme which participates in the ammonia assimilation process by catalysing the formation of glutamate from glutamine and 2-oxoglutarate. Glutamate synthase is a multicomponent iron-sulphur flavoprotein and three types occur which use a different electron donor: NADPH-dependent gltS (large chain), ferredoxin-dependent gltS and NADH-dependent gltS [[cite:PUB00009386]].</li> </ul> <p>The active site is formed by a cysteine present at the N-terminal extremity of the mature form of all these enzymes [[cite:PUB00002391], [cite:PUB00043790], [cite:PUB00043761], [cite:PUB00043791]]. Two other conserved residues, Asn and Gly, form an oxyanion hole for stabilisation of the formed tetrahedral intermediate. An insert of ~120 residues can occur between the conserved regions [[cite:PUB00009386]]. In some class-II GATases (for example in Bacillus subtilis or chicken amido phosphoribosyltransferase) the enzyme is synthesised with a short propeptide which is cleaved off post-translationally by a proposed autocatalytic mechanism. Nuclear-encoded Fd-dependent gltS have a longer propeptide which may contain a chloroplast-targeting peptide in addition to the propeptide that is excised on enzyme activation.</p> <p>The 3-D structure of the GATase type 2 domain forms a four layer α/β/β/α architecture which consists of a fold similar to the N-terminal nucleophile (Ntn) hydrolases. These have the capacity for nucleophilic attack and the possibility of autocatalytic processing. The N-terminal position and the folding of the catalytic Cys differ strongly from the Cys-His-Glu triad which forms the active site of GATases of type 1.</p>

This description is obtained from EB-eye REST.

Associated GO terms

Unable to find any GO terms for the transcript with the identifier.

Associated Lotus transcripts 54

Co-occuring domains 1

A list of co-occurring predicted domains within the L. japonicus gene space: