Heterologous expression, purification, and enzymatic characterization of the acyclic carotenoid 1,2-hydratase from Rubrivivax gelatinosus.
The carotenoid 1,2-hydratase CrtC from Rubrivivax gelatinosus has been expressed in Escherichia coli in an active form and purified by affinity chromatography. The enzyme catalyzes the conversion of various acyclic carotenes including 1-hydroxy derivatives. This broad substrate specificity reflects the participation of CrtC in 1'-HO-spheroidene and in spirilloxanthin biosynthesis. Enzyme kinetic studies including the determination of substrate specificity constants indicate that among the alternative biosynthetic routes to 1'-HO-spheroidene the one via spheroidene is the dominating pathway. In contrast to CrtC from Rvi. gelatinosus, the equivalent enzyme from Rhodobacter capsulatus, a closely related bacterium which lacks the biosynthetic branch to spirilloxanthin and accumulates spheroidene instead of substantial amounts of 1'-HO-spheroidene, is extremely poor in converting 1-HO-carotenoids. The individual catalytic properties of both carotenoid 1,2-hydratases reflect the in situ carotenogenic pathways in both purple photosynthetic bacteria.
Biosynthesis Group, Botanical Institute, J. W. Goethe Universität, P.O. Box 111932, Frankfurt D-60054, Germany.
Sabine
S
Steiger
Andreas
A
Mazet
Gerhard
G
Sandmann
D002338:Carotenoids / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D002846:Chromatography, Affinity / Q000379:methods; D004789:Enzyme Activation; D004926:Escherichia coli / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D006836:Hydro-Lyases / Q000737:chemistry* / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D020560:Proteobacteria / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D016354:Rhodobacter capsulatus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D013045:Species Specificity; D013379:Substrate Specificity; D024341:Xanthophylls / Q000031:analogs & derivatives* / Q000096:biosynthesis
D011994:Recombinant Proteins; D024341:Xanthophylls; C005637:spheroidene; D002338:Carotenoids; D006836:Hydro-Lyases; C475147:carotenoid 1,2-hydratase; C055255:spirilloxanthin