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

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