Open AccessCarotenogenesis gene cluster and phytoene desaturase catalyzing both three‐ and four‐step desaturations from R hodobacter azotoformans
Author(s) -
Zhang Jinhua,
Lu Lili,
Yin Lijie,
Xie Shen,
Xiao Min
Publication year - 2012
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2012.02604.x
Subject(s) - phytoene , phytoene desaturase , rhodobacter , biology , gene cluster , lycopene , biochemistry , escherichia coli , phytoene synthase , carotenoid , gene , biosynthesis , mutant
A carotenogenesis gene cluster from the purple nonsulfur photosynthetic bacterium R hodobacter azotoformans CGMCC 6086 was cloned. A total of eight carotenogenesis genes ( crtA , crtI , crtB , tspO , crtC , crtD , crtE , and crtF ) were located in two separate regions within the genome, a 4.9 kb region containing four clustered genes of crtAIB ‐ tspO and a 5.3 kb region containing four clustered genes of crtCDEF . The organization was unusual for a carotenogenesis gene cluster in purple photosynthetic bacteria. A gene encoding phytoene desaturase ( CrtI ) from R ba. azotoformans was expressed in E scherichia coli . The recombinant CrtI could catalyze both three‐ and four‐step desaturations of phytoene to produce neurosporene and lycopene, and the relative contents of neurosporene and lycopene formed by CrtI were approximately 23% and 75%, respectively. Even small amounts of five‐step desaturated 3,4‐didehydrolycopene could be produced by CrtI . This product pattern was novel because CrtI produced only neurosporene leading to spheroidene pathway in the cells of R ba. azotoformans . In the in vitro reaction, the relative content of lycopene in desaturated products increased from 19.6% to 62.5% when phytoene reduced from 2.6 to 0.13 μM. The results revealed that the product pattern of CrtI might be affected by the kinetics.