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Updated: Oct 9, 2026

In Vitro Reconstitution of Light-harvesting Complexes of Plants and Green Algae
Published on: October 10, 2014
Molecular evolution of lycopene cyclases involved in the formation of carotenoids with ionone end groups
1Biosynthesis Group, Botanical Institute, J.W. Goethe Universität, P.O. Box 111930, D-60054 Frankfurt, Germany.
Abstract:
A survey is given of the lycopene cyclase genes present in bacteria, fungi and plants where two completely unrelated types exist. One is the classical monomeric bacterial beta-cyclase gene, crtY, which may be an ancestor of crtL, the gene for a beta-cyclase in cyanobacteria. From crtL a line of evolution can be drawn to plant beta- and epsilon-cyclase genes and to the gene of capsanthin/capsorubin synthase. In Gram-positive bacteria two genes crtYc and crtYd are present. They encode two proteins which have to interact as a heterodimer for lycopene beta-cyclization. From this type of lycopene cyclase gene the fungal lycopene cyclase/phytoene synthase fusion gene evolved.
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Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
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The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.

