Catalyzes the ATP-dependent conversion of 5-aminoimidazole ribonucleotide (AIR) and HCO(3)(-) to N5-carboxyaminoimidazole ribonucleotide (N5-CAIR). 5-amino-1-(5-phospho-beta-D-ribosyl)imidazole + ATP + hydrogencarbonate = 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole + ADP + 2 H(+) + phosphate Purine metabolism; IMP biosynthesis via de novo pathway; 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate from 5-amino-1-(5-phospho-D-ribosyl)imidazole (N5-CAIR route): step 1/2. Homodimer. Belongs to the PurK/PurT family.