Publications

• Novel activity of Rhodobacter sphaeroides spheroidene monooxygenase CrtA expressed in Escherichia coli.

  Lee P.C., Holtzapple E., Schmidt-Dannert C.

  The spheroidene monooxygenase CrtA of Rhodobacter sphaeroides introduces a keto group and/or hydroxy group at the ends of nonnative substrates in Escherichia coli, resulting in the production of novel oxocarotenoids. The heme-containing CrtA is not a P450 enzyme but a new type of oxygenase.

  Appl. Environ. Microbiol. 76:7328-7331(2010) [PubMed] [EuropePMC]

  This publication is cited by 11 other entries.

• Catalytic properties of the expressed acyclic carotenoid 2-ketolases from Rhodobacter capsulatus and Rubrivivax gelatinosus.

  Gerjets T., Steiger S., Sandmann G.

  Purple photosynthetic bacteria synthesize the acyclic carotenoids spheroidene and spirilloxanthin which are ketolated to spheroidenone and 2,2'-diketospirilloxanthin under aerobic growth. For the studies of the catalytic reaction of the ketolating enzyme, the crtA genes from Rubrivivax gelatinosus ... >> More

  Purple photosynthetic bacteria synthesize the acyclic carotenoids spheroidene and spirilloxanthin which are ketolated to spheroidenone and 2,2'-diketospirilloxanthin under aerobic growth. For the studies of the catalytic reaction of the ketolating enzyme, the crtA genes from Rubrivivax gelatinosus and Rhodobacter capsulatus encoding acyclic carotenoid 2-ketolases were expressed in Escherichia coli to functional enzymes. With the purified enzyme from the latter, the requirement of molecular oxygen and reduced ferredoxin for the catalytic activity was determined. Furthermore, the putative intermediate 2-HO-spheroidene was in vitro converted to the corresponding 2-keto product. Therefore, a monooxygenase mechanism involving two consecutive hydroxylation steps at C-2 were proposed for this enzyme. By functional pathway complementation studies in E. coli and enzyme kinetic studies, the product specificity of both enzymes were investigated. It appears that the ketolases could catalyze most intermediates and products of the spheroidene and spirilloxanthin pathway. This was also the case for the enzyme from Rba. capsulatus from which spirilloxanthin synthesis is absent. In general, the ketolase of Rvi. gelatinosus had a better specificity for spheroidene, HO-spheroidene and spirilloxanthin as substrates than the ketolase from Rba. capsulatus. << Less

  Biochim. Biophys. Acta 1791:125-131(2009) [PubMed] [EuropePMC]

  This publication is cited by 11 other entries.