Abstract
Anabaena sp. PCC7120 is a filamentous, heterocystous cyanobacterium, and its entire genome has already been analyzed. In spite of its prominency as an experimental material, pigments of this species have not been adequately characterized. Recently, pigments of another cyanobacterium Synechocystis sp. PCC6803 have been identified; myxol 2'-dimethyl-fucoside, not rhamnoside, β-carotene, zeaxanthin and echinenone (Takaichi et al. (2001) PCP).
In this study, we identified the pigments of Anabaena sp. PCC7120. (3R,2'S)-Myxol 2'-fucoside (12%, mol% of total carotenoids) and (3S,2'S)-4-keto-myxol 2'-fucoside (6%) were polar carotenoids. Other carotenoids were β-carotene (56%), echinenone (26%), canthaxanthin (1%) and β-cryptoxanthin (1%). Therefore β-carotene hydroxylase (CrtR) seems to have unique characteristics, that is, β-end group of deoxymyxol is a good substrate to produce myxol, but that of β-carotene is not a substrate to produce zeaxanthin. Pathway of carotenoid synthesis will be discussed.
