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- Title
Opposite Chilarity of α-Carotene in Unusual Cyanobacteria with Unique Chlorophylls, Acaryochloris and Prochlorococcus.
- Authors
Takaichi, Shinichi; Mochimaru, Mari; Uchida, Hiroko; Murakami, Akio; Hirose, Euichi; Maoka, Takashi; Tsuchiya, Tohru; Mimuro, Mamoru
- Abstract
Among all photosynthetic and non-photosynthetic prokaryotes, only cyanobacterial species belonging to the genera Acaryochloris and Prochlorococcus have been reported to synthesize α-carotene. We reviewed the carotenoids, including their chirality, in unusual cyanobacteria containing diverse Chls. Predominantly Chl d-containing Acaryochloris (two strains) and divinyl-Chl a and divinyl-Chl b-containing Prochlorococcus (three strains) contained β-carotene and zeaxanthin as well as α-carotene, whereas Chl b-containing Prochlorothrix (one strain) and Prochloron (three isolates) contained only β-carotene and zeaxanthin but no α-carotene as in other cyanobacteria. Thus, the capability to synthesize α-carotene seemed to have been acquired only by Acaryochloris and Prochlorococcus. In addition, we unexpectedly found that α-carotene in both cyanobacteria had the opposite chirality at C-6′: (6′S)-chirality in Acaryochloris and normal (6′R)-chirality in Prochlorococcus, as reported in some green algae and land plants. The results represent the first evidence for the natural occurrence and biosynthesis of (6′S)-α-carotene. All the zeaxanthins in these species were of the usual (3R,3′R)-chirality. Therefore, based on the identification of the carotenoids and genome sequence data, we propose a biosynthetic pathway for the carotenoids, particularly α-carotene, including the participating genes and enzymes.
- Subjects
BETA carotene; CYANOBACTERIAL genetics; BACTERIAL genetics; CHIRALITY; CHLOROPHYLL synthesis; PROCHLOROCOCCUS; GENETICS
- Publication
Plant & Cell Physiology, 2012, Vol 53, Issue 11, p1881
- ISSN
0032-0781
- Publication type
Article
- DOI
10.1093/pcp/pcs126