The cyanobacterium Anabaena sp. PCC 7120 has two distinct beta-carotene ketolases: CrtO for echinenone and CrtW for ketomyxol synthesis.
Two beta-carotene ketolases, CrtW and CrtO, are widely distributed in bacteria, although they show no significant sequence homology with each other. The cyanobacterium Anabaena sp. PCC 7120 was found to have two homologous genes. In the crtW deleted mutant, myxol 2'-fucoside was present, but ketomyxol 2'-fucoside was absent. In the crtO deleted mutant, beta-carotene was accumulated, and the amount of echinenone was decreased. Therefore, CrtW catalyzed myxol 2'-fucoside to ketomyxol 2'-fucoside, and CrtO catalyzed beta-carotene to echinenone. This cyanobacterium was the first species found to have both enzymes, which functioned in two distinct biosynthetic pathways.
Mochimaru
Mari
M
Natural Science Faculty, Komazawa University, Tokyo 154-8525, Japan.
Masukawa
Hajime
H
Takaichi
Shinichi
S
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002338:Carotenoids / Q000096:biosynthesis*; D017353:Gene Deletion; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D005960:Glucosides / Q000096:biosynthesis*; D046937:Nostoc / Q000201:enzymology* / Q000235:genetics; D010105:Oxygenases / Q000235:genetics* / Q000378:metabolism; D019207:beta Carotene / Q000096:biosynthesis
D001426:Bacterial Proteins; D005960:Glucosides; C506423:ketomyxol 2'-fucoside; C488895:myxol; D019207:beta Carotene; D002338:Carotenoids; D010105:Oxygenases; C093259:beta-carotene ketolase; C105515:echinenone