Journal Article

Phytoene Desaturase, CrtI, of the Purple Photosynthetic Bacterium, <i>Rubrivivax gelatinosus</i>, Produces both Neurosporene and Lycopene

Jiro Harada, Kenji V. P. Nagashima, Shinichi Takaichi, Norihiko Misawa, Katsumi Matsuura and Keizo Shimada

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 10, pages 1112-1118
Published in print October 2001 | ISSN: 0032-0781
Published online October 2001 | e-ISSN: 1471-9053 | DOI:
Phytoene Desaturase, CrtI, of the Purple Photosynthetic Bacterium, Rubrivivax gelatinosus, Produces both Neurosporene and Lycopene

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry


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Biosynthetic pathways for carotenoids in the purple photosynthetic bacterium, Rubrivivax gelatinosus, which synthesizes spirilloxanthin in addition to spheroidene and OH-spheroidene, were investigated by means of genetic manipulation. A phytoene desaturase gene (crtI) found in the photosynthesis gene cluster of this bacterium was expressed in an Escherichia coli strain that can produce phytoene. Both neurosporene and lycopene were synthesized in the recombinant, probably by three- and four-step desaturation reactions of CrtI. A mutant of Rvi. gelatinosus lacking the crtI gene produced only phytoene, indicating that this organism had no other phytoene desaturases. When the crtI deletion mutant was complemented by the three-step phytoene desaturase of Rhodobacter capsulatus, spirilloxanthin and its precursors were not synthesized, although spheroidene and OH-spheroidene were accumulated. It was concluded that neurosporene and lycopene are produced by a single phytoene desaturase in Rvi. gelatinosus resulting in the synthesis of spheroidene and spirilloxanthin, and that there are no pathways for spirilloxanthin synthesis via spheroidene.

Keywords: Key words: Carotenoid — Carotenoid biosynthesis gene — CrtI — Phytoene desaturase — Purple photosynthetic bacteria — Rubrivivax gelatinosus.

Journal Article.  3796 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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