1o4v

Protein Summary

The TM0446 gene of Thermotoga maritima encodes the NP_228256 protein, a N⁵-Carboxyaminoimidazole ribonucleotide (N⁵-CAIR) mutase (PurE, AIRC, EC 4.1.1.21, member of COG0041, PF00731), that catalyzes the only C-C-bond-forming reaction in de novo purine biosynthesis, the formation of 4-carboxy-5-aminoimidazole ribonucleotide (CAIR) (PubMed:15048837).

1o4v has a flavodoxin-like fold (SCOP sunid:52171) with 3 layers, a/b/a; parallel beta-sheet of 5 strand, order 21345 and belongs to family of N⁵-CAIR mutases (SCOP sunid:52256). Dali top hits are with the carboxylases/mutases 1xmp (Z-scr=28), 2fwa (Z-scr=27),

PurE proteins are highly conserved and designated as Class I or Class II according to their enzymatic activity. Class I enzymes, found in yeast, plants, and prokaryotes, catalyze the second of a two-step conversion of 5-aminoimidazole ribonucleotide (AIR), via the intermediate N5-carboxyaminoimidazole ribonucleotide (N5-CAIR), to 4-carboxy-5-aminoimidazole ribonucleotide (CAIR) (PubMed:8117684, 10074353). The conversion of AIR to N⁵-CAIR is catalyzed by N⁵-CAIR synthetase (PurK) in the presence of ATP and bicarbonate. Class II enzymes from higher eukaryotes catalyze the conversion of AIR to CAIR directly, in the presence of bicarbonate or CO₂. Therefore, Class I PurE proteins function as phosphoribosylaminoimidazole mutases, while Class II enzymes are carboxylases.

Ligand Summary

References