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):

  The novo purine biosynthesis proceeds by two divergent paths. In bacteria, yeasts, and plants, 5-aminoimidazole ribonucleotide (AIR) is converted to 4-carboxy-AIR (CAIR) by two enzymes: N5-carboxy-AIR (N5-CAIR) synthetase (PurK) and N5-CAIR mutase (class I PurE). In animals, the conversion of AIR to CAIR requires a single enzyme, AIR carboxylase (class II PurE) [ (PUBMED:7918411) ]. Class I and class II PurEs are mechanistically related but bind different substrates. In yeast and plants PurE is found in PurK-class I PurE fusion proteins, known as ADE2 [ (PUBMED:8111040) (PUBMED:9500840) ], while animal class II PurEs are found in PurC-PurE fusion proteins, also known as ADE2 or PAICS [ (PUBMED:7918410) ].

• GO process: 'de novo' IMP biosynthetic process (GO:0006189)

There are 23473 AIRC domains in 23424 proteins in SMART's nrdb database.

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

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	Title
1d7a	CRYSTAL STRUCTURE OF E. COLI PURE-MONONUCLEOTIDE COMPLEX.
1o4v	Crystal structure of the catalytic subunit of a phosphoribosylaminoimidazole mutase (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
3kuu	Structure of the PurE Phosphoribosylaminoimidazole Carboxylase Catalytic Subunit from Yersinia pestis
3lp6	Crystal Structure of Rv3275c-E60A from Mycobacterium tuberculosis at 1.7A resolution
3oow	Octameric structure of the phosphoribosylaminoimidazole carboxylase catalytic subunit from Francisella tularensis subsp. tularensis SCHU S4.
3opq	Phosphoribosylaminoimidazole carboxylase with fructose-6-phosphate bound to the central channel of the octameric protein structure.
3ors	Crystal Structure of N5-Carboxyaminoimidazole Ribonucleotide Mutase from Staphylococcus aureus
3rg8	Crystal structure of Treponema denticola PurE
3rgg	Crystal structure of Treponema denticola PurE bound to AIR
3trh	Structure of a phosphoribosylaminoimidazole carboxylase catalytic subunit (purE) from Coxiella burnetii
4ay3	Crystal structure of Bacillus anthracis PurE
4ay4	crystal structure of Bacillus anthracis PurE
4b4k	Crystal structure of Bacillus anthracis PurE
4grd	Crystal structure of Phosphoribosylaminoimidazole carboxylase catalytic subunit from Burkholderia cenocepacia J2315
4ja0	Crystal structure of the invertebrate bi-functional purine biosynthesis enzyme PAICS at 2.8 A resolution
4ycb	4YCB
4ycc	4YCC
4ycd	4YCD
4ycj	4YCJ
4z7j	4Z7J
4zc8	4ZC8
4zjy	4ZJY
4zk2	4ZK2
4zmb	4ZMB
5bor	5BOR
5bos	5BOS
5c5d	5C5D
5clf	5CLF
5clg	5CLG
5clh	5CLH
5cli	5CLI
5clj	5CLJ
5ctj	5CTJ
5cvt	5CVT

Links (links to other resources describing this domain)

• PFAM: AIRC
• INTERPRO: IPR000031