SMART: AIRC domain annotation

AIRC AIR carboxylase

SMART accession number:	SM01001
Description:	Members of this family catalyse the decarboxylation of 1-(5-phosphoribosyl)-5-amino-4-imidazole-carboxylate (AIR). This family catalyse the sixth step of de novo purine biosynthesis. Some members of this family contain two copies of this domain.
Interpro abstract (IPR000031):	Phosphoribosylaminoimidazole carboxylase is a fusion protein in plants and fungi, but consists of two non-interacting proteins in bacteria, PurK and PurE, which were previously thought to be subunits of a single enzyme, AIR carboxylase [(PUBMED:9219341)]. PurK, N5-carboxyaminoimidazole ribonucleotide (N5_CAIR) synthetase, catalyses the conversion of 5-aminoimidazole ribonucleotide (AIR), ATP, and bicarbonate to N5-CAIR, ADP, and Pi. PurE catalyses the reversible conversion of N5-CAIR and CAIR [(PUBMED:10074353)], the sixth step of de novo purine biosynthesis. In the presence of high concentrations of bicarbonate, PurE is reported able to convert AIR to CAIR directly and without ATP [(PUBMED:7918411)]. The crystal structure of PurE indicates a unique quaternary structure that confirms the octameric nature of the enzyme [(PUBMED:10574791)].
GO process:	'de novo' IMP biosynthetic process (GO:0006189)
GO function:	5-(carboxyamino)imidazole ribonucleotide mutase activity (GO:0034023)
Family alignment:	View or

There are 1973 AIRC domains in 1966 proteins in SMART's nrdb database.

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Evolution (species in which this domain is found)
Click on to expand nodes. To display all proteins with a AIRC domain in a specific node, click on it.

This tree shows only several representative species. The complete taxonomic breakdown of all proteins with AIRC domain is also avaliable.

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Go to specific node: Anopheles gambiae, Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, Homo sapiens, Mus musculus, Rattus norvegicus, Saccharomyces cerevisiae, Takifugu rubripes
Cellular role (predicted cellular role)
Cellular role: metabolism
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
- Mathews II, Kappock TJ, Stubbe J, Ealick SE
- Crystal structure of Escherichia coli PurE, an unusual mutase in thepurine biosynthetic pathway.
- Structure. 1999; 7: 1395-406
- Display abstract
- BACKGROUND: Conversion of 5-aminoimidazole ribonucleotide (AIR) to4-carboxyaminoimidazole ribonucleotide (CAIR) in Escherichia coli requirestwo proteins - PurK and PurE. PurE has recently been shown to be a mutasethat catalyzes the unusual rearrangement of N(5)-carboxyaminoimidazoleribonucleotide (N(5)-CAIR), the PurK reaction product, to CAIR. PurEs fromhigher eukaryotes are homologous to E. coli PurE, but use AIR and CO(2) assubstrates to produce CAIR directly. RESULTS: The 1.50 A crystal structureof PurE reveals an octameric structure with 422 symmetry. A centralthree-layer (alphabetaalpha) sandwich domain and a kinked C-terminal helixform the folded structure of the monomeric unit. The structure reveals acleft at the interface of two subunits and near the C-terminal helix of athird subunit. Co-crystallization experiments with CAIR confirm this to bethe mononucleotide-binding site. The nucleotide is bound predominantly toone subunit, with conserved residues from a second subunit making up onewall of the cleft. CONCLUSIONS: The crystal structure of PurE reveals aunique quaternary structure that confirms the octameric nature of theenzyme. An analysis of the native crystal structure, in conjunction withsequence alignments and studies of co-crystals of PurE with CAIR, revealsthe location of the active site. The environment of the active site andthe analysis of conserved residues between the two classes of PurEssuggests a model for the differences in their substrate specificities andthe relationship between their mechanisms.
Structure (3D structures containing this domain)

3D Structures of AIRC domains in PDB

PDB code	Main view	Title
1d7a		Crystal structure of e. coli pure-mononucleotide complex.
1o4v		Crystal structure of phosphoribosylaminoimidazole mutase pure (tm0446) from thermotoga maritima at 1.77 a resolution
1qcz		Crystal structure of e. coli pure, an unusual mutase that catalyzes the conversion of n5-carboxyaminoimidazole ribonucleotide (n5-cair) to 4-carboxyaminoimidazole ribonucleotide (cair) in the purine biosynthetic pathway
1u11		Pure (n5-carboxyaminoimidazole ribonucleotide mutase) from the acidophile acetobacter aceti
1xmp		Crystal structure of pure (ba0288) from bacillus anthracis at 1.8 resolution
2ate		Structure of the complex of pure with nitroair
2fw1		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) from the acidophilic bacterium acetobacter aceti, at ph 8.5
2fw6		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) mutant h59n from the acidophilic bacterium acetobacter aceti, at ph 5.4
2fw7		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) h59n from the acidophilic bacterium acetobacter aceti, at ph 8
2fw8		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) h89g from the acidophilic bacterium acetobacter aceti, at ph 8
2fw9		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) h59f from the acidophilic bacterium acetobacter aceti, at ph 8
2fwa		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) h89n from the acidophilic bacterium acetobacter aceti, at ph 7
2fwb		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) h89f from the acidophilic bacterium acetobacter aceti, at ph 8
2fwi		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) h59d, from the acidophilic bacterium acetobacter aceti, complexed with 5-aminoimidazole ribonucleotide (air)
2fwj		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) from the acidophilic bacterium acetobacter aceti, complexed with air (5-aminoimidazole ribonucleotide)
2fwp		Structure of pure (n5-carboxyaminoimidazole ribonucleotide mutase) h59n from the acidophilic bacterium acetobacter aceti, bound to isocair
2h31		Crystal structure of human paics, a bifunctional carboxylase and synthetase in purine biosynthesis
2nsh		E. coli pure h45q mutant complexed with nitro-air
2nsj		E. coli pure h45q mutant complexed with cair
2nsl		E. coli pure h45n mutant complexed with cair
2ywx		Crystal structure of phosphoribosylaminoimidazole carboxylase catalytic subunit from methanocaldococcus jannaschii

Links (links to other resources describing this domain)
PFAM AIRC
INTERPRO IPR000031

PFAM	AIRC
INTERPRO	IPR000031