Carotenoids of Gemmatimonas aurantiaca (Gemmatimonadetes): identification of a novel carotenoid, deoxyoscillol 2-rhamnoside, and proposed biosynthetic pathway of oscillol 2,2'-dirhamnoside.
Gemmatimonas aurantiaca strain T-27(T) is an orange-coloured, Gram-negative, facultatively aerobic, polyphosphate-accumulating bacterium belonging to a recently proposed phylum, Gemmatimonadetes. We purified its pigments and identified them as carotenoids and their glycoside derivatives using spectral data. The major carotenoid was (2S,2' S)-oscillol 2,2'-di-(alpha-l-rhamnoside), and the minor carotenoids were (2S)-deoxyoscillol 2-( alpha-l-rhamnoside) and didemethylspirilloxanthin. Deoxyoscillol 2-rhamnoside is a novel carotenoid. Oscillol 2,2'-diglycosides have hitherto only been reported in a limited number of cyanobacteria, and this is believed to be the first finding of such carotenoids in another bacterial phylum. Based on the identification of the carotenoids and the completion of the entire nucleotide sequence, we propose a biosynthetic pathway for the carotenoids and the corresponding genes and enzymes. We propose the involvement of geranylgeranyl pyrophosphate synthase (CrtE), phytoene synthase (CrtB) and phytoene desaturase (CrtI) for lycopene synthesis; and of carotenoid 1,2-hydratase (CruF) and carotenoid 2-O-rhamnosyltransferase (CruG) for oscillol 2,2'-dirhamnoside synthesis. Further, isopentenyl pyrophosphate could be synthesized by a non-mevalonate pathway (DXP pathway).
Takaichi
Shinichi
S
Department of Biology, Nippon Medical School, Kosugi-cho2, Nakahara, Kawasaki 211-0063, Japan.
Maoka
Takashi
T
Research Institute for Production Development, Shimogamo-morimoto-cho, Sakyo, Kyoto 606-0805, Japan.
Takasaki
Kazuto
K
Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan.
Hanada
Satoshi
S
Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan.
D001419:Bacteria / Q000737:chemistry* / Q000201:enzymology; D001426:Bacterial Proteins / Q000378:metabolism; D002338:Carotenoids / Q000096:biosynthesis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D006027:Glycosides / Q000096:biosynthesis* / Q000737:chemistry; D006602:Hexosyltransferases / Q000378:metabolism; D006836:Hydro-Lyases / Q000378:metabolism; D000077276:Lycopene; D015394:Molecular Structure
D001426:Bacterial Proteins; D006027:Glycosides; C550339:deoxyoscillol 2-rhamnoside; C550340:oscillol 2,2'-dirhamnoside; D002338:Carotenoids; D006602:Hexosyltransferases; D006836:Hydro-Lyases; C475147:carotenoid 1,2-hydratase; D000077276:Lycopene