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Query: UMLS:C1832526 (PCC)
 5,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Carotene isomerase mutant (crtH mutant) cells of Synechocystis sp. PCC 6803 can accumulate beta-carotene under light conditions. However, the mutant cells grown under a light-activated heterotrophic growth condition contained detectable levels of neither beta-carotene nor D1 protein of the photosystem (PS) II reaction center, and no oxygen-evolving activity of PSII was detected. beta-Carotene and D1 protein appeared and a high level of PSII activity was detected after the cells were transferred to a continuous light condition. The PSI activities of thylakoid membranes from mutant cells were almost the same as those of thylakoid membranes from wild-type cells, both before and after transfer to the continuous light condition. These results suggest that beta-carotene is required for the assembly of PSII but not for that of PSI.
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PMID:Requirement of carotene isomerization for the assembly of photosystem II in Synechocystis sp. PCC 6803. 1550 57

Carotenoid composition and its biosynthetic pathway in the cyanobacterium Gloeobacter violaceus PCC 7421 were investigated. beta-Carotene and (2S,2'S)-oscillol 2,2'-di(alpha-L-fucoside), and echinenone were major and minor carotenoids, respectively. We identified two unique genes for carotenoid biosynthesis using in vivo functional complementation experiments. In Gloeobacter, a bacterial-type phytoene desaturase (CrtI), rather than plant-type desaturases (CrtP and CrtQ), produced lycopene. This is the first demonstration of an oxygenic photosynthetic organism utilizing bacterial-type phytoene desaturase. We also revealed that echinenone synthesis is catalyzed by CrtW rather than CrtO. These findings indicated that Gloeobacter retains ancestral properties of carotenoid biosynthesis.
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PMID:The cyanobacterium Gloeobacter violaceus PCC 7421 uses bacterial-type phytoene desaturase in carotenoid biosynthesis. 1581 29

Carotenoid cleavage dioxygenases (CCDs) are a class of enzymes that oxidatively cleave carotenoids into apocarotenoids. Dioxygenases have been identified in plants and animals and produce a wide variety of cleavage products. Despite what is known about apocarotenoids in higher organisms, very little is known about apocarotenoids and CCDs in microorganisms. This study surveyed cleavage activities of ten putative carotenoid cleavage dioxygenases from five different cyanobacteria in recombinant Escherichia coli cells producing different carotenoid substrates. Three CCD homologs identified in Nostoc sp. PCC 7120 were purified, and their cleavage activities were investigated. Two of the three enzymes showed cleavage of beta,beta-carotene at the 9,10 and 15,15' positions, respectively. The third enzyme did not cleave full-length carotenoids but cleaved the apocarotenoid beta-apo-8'-carotenal at the 9,10 position. 9,10-Apocarotenoid cleavage specificity has previously not been described. The diversity of carotenoid cleavage activities identified in one cyanobacteria suggests that CCDs not only facilitate the degradation of photosynthetic pigments but generate apocarotenals with yet to be determined biological roles in microorganisms.
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PMID:Identification of carotenoid cleavage dioxygenases from Nostoc sp. PCC 7120 with different cleavage activities. 1692 Jul 3