The zeaxanthin biosynthesis enzyme beta-carotene hydroxylase is involved in myxoxanthophyll synthesis in Synechocystis sp. PCC 6803.
Beta-carotene hydroxylase is known to be involved in zeaxanthin synthesis. Disruption of the crtR gene encoding beta-carotene hydroxylase in Synechocystis sp. PCC 6803 resulted in the absence of both zeaxanthin synthesis and myxoxanthophyll accumulation in the mutant strain. A new carotenoid was detected in this strain. Its chemical structure was close to that of myxoxanthophyll, but the hydroxyl group on the beta-ring was lacking. This compound, deoxy-myxoxanthophyll, most likely is an intermediate in the myxoxanthophyll biosynthesis pathway. Therefore, beta-carotene hydroxylase is involved not only in zeaxanthin synthesis but also in myxoxanthophyll synthesis in Synechocystis. Furthermore, myxoxanthophyll in Synechocystis was found to have a higher molecular mass than what was determined in other species. This difference is likely to be due to a difference in the sugar moiety.
Lagarde
D
D
Department of Plant Biology and Center for the Study of Early Events in Photosynthesis, Arizona State University, Tempe 85287-1601, USA. d_lagarde@hotmail.com
Vermaas
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W
D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009154:Mutation; D013379:Substrate Specificity; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000096:biosynthesis
D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D006899:Mixed Function Oxygenases; C079232:beta-carotene hydroxylase