The Carotenoid 7, 8‐Dihydro‐ψ end Group can be Cyclized by the Lycopene Cyclases from the Bacterium Erwinia Uredovora and the Higher Plant Capsicum Annuum

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Abstract
The genes for geranylgeranyl diphosphate synthase (crtE) and phytoene synthase (crtB) from the epiphytic bacterium Erwinia uredovora and the phytoene desaturase gene from the photosynthetic bacterium Rhodobacter capsulatus (Rc-crtI) were introduced into Escherichia coli, which resulted in the accumulation of the acyclic carotenoid, neurosporene. Further introduction of the lycopene cyclase gene from E. uredovora (crtY) or the higher plant Capsicum annuum (Icy) resulted in the production of a bicyclic carotenoid, 7,8-dihydro-β-carotene, via monocyclic β-zeacarotene. ζ-Carotene was also found to be cyclized to bicyclic 7,8,7′,8′-tetrahydro-β-carotene by the Erwinia cyclase. These results indicate that both lycopene cyclases can cyclize a 7,8-dihydro-ψ end group to a 7,8-dihydro-β end group, in addition to the usual cyclization of the ψ end group to the β end group. Furthermore, β-carotene hydroxylase from Enwnia (CrtZ) was able to add a hydroxyl group to the 7,8-dihydro-β end group and the β end group.