The biotechnological potential of the al-2 gene from Neurospora [correction of Neurospra] crassa for the production of monocyclic keto hydroxy carotenoids.
The al-2 cDNA from Neurospora crassa was cloned, expressed and functionally characterized. The enzyme comprised the two catalytic activities of a phytoene synthase and a lycopene cyclase. In contrast to most other lycopene cyclases, single cyclizations were preferentially catalyzed. This N. crassa enzyme is the first CrtYB-type monocyclic-acting lycopene cyclase. Therefore, this cDNA has been evaluated for the heterologous synthesis of monocyclic hydroxy-keto carotenoids by combination with other carotenogenic genes in Escherichia coli. Depending on the degree of desaturation, 4-keto derivatives of gamma-carotene and torulene with additional 2-hydroxy, 3-hydroxy and/or 1'-HO groups were generated and the following asymmetrical carotenoids identified and quantitated: 3-HO-4-keto-gamma-carotene, 2-HO-4-keto-gamma-carotene, 4-keto-1'-HO-gamma-carotene, 3,1'-(HO)(2)-4-keto-gamma-carotene, 3-HO-4-keto-torulene and 2-HO-4-keto-torulene. Among them all the monocyclic gamma-carotene derivatives with 9 conjugated double bonds were not found naturally before. Furthermore, 2-HO-4-keto-torulene with 10 conjugated double bonds is another novel carotenoid.
Sandmann
Gerhard
G
Biosynthesis Group, Molecular Biosciences 213, J.W. Goethe Universität, P.O. Box 111932, D-60054 Frankfurt, Germany. Sandmann@em.uni-frankfurt.de
Zhu
Changfu
C
Krubasik
Philipp
P
Fraser
Paul D
PD
D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism*; D002338:Carotenoids / Q000096:biosynthesis*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D019753:Intramolecular Lyases / Q000235:genetics / Q000378:metabolism*; D007659:Ketones / Q000378:metabolism*; D009492:Neurospora crassa / Q000201:enzymology*
D005656:Fungal Proteins; D007659:Ketones; D002338:Carotenoids; C078922:torulene; D019883:Alkyl and Aryl Transferases; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D019753:Intramolecular Lyases; C070925:lycopene cyclase-isomerase