Carotenoid biosynthetic pathway and the genes involved in the biosynthesis of zeaxanthin in <i>Sphingobium yanoikuyae</i> XLDN2-5.

<p>(<b>A</b>) Genetic organization of the <i>crt</i> genes in strain XLDN2-5 compared to similar gene clusters from other bacteria. (<b>B</b>) The proposed carotenoid biosynthetic pathway in strain XLDN2-5 is inside the red box. CrtE: GGPP synthase (orange); CrtB: Phytoene synthase (green); CrtI: Phytoene dehydrogenase (red); CrtY: Lycopene cyclase (blue); CrtZ: <i>β</i>-Carotene hydroxygenase (magenta); CrtW: <i>β</i>-Carotene ketolase (black); CrtX: Zeaxanthin glucosyltransferase (purple); orfX1 and orfX2: No predicted function (grey). The percent of numbers represents the amino acid (aa) identities of related enzymes.