| Institution: | 1. Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20, Shinmachi, Nishitokyo-shi, Tokyo, 202-8585 Japan;2. Faculty of Pharmacy, Department of Pharmaceutical Sciences, Musashino University, 1-1-20, Shinmachi, Nishitokyo-shi, Tokyo, 202-8585 Japan
These authors contributed equally to this work.;3. Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima, 734-8553 Japan;4. National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki, 305-8642 Japan |
| Abstract: | A plethora of dimeric natural products exist with diverse chemical structures and biological activities. A major strategy for dimerization is aryl coupling catalyzed by cytochrome P450 or laccase. Actinorhodin (ACT) from Streptomyces coelicolor A3(2) has a dimeric pyranonaphthoquinone structure connected by a C?C bond. In this study, we identified an NmrA-family dimerizing enzyme, ActVA-ORF4, and a cofactor-independent oxidase, ActVA-ORF3, both involved in the last step of ACT biosynthesis. ActVA-ORF4 is a unique NAD(P)H-dependent enzyme that catalyzes the intermolecular C?C bond formation using 8-hydroxydihydrokalafungin (DHK-OH) as the sole substrate. On the other hand, ActVA-ORF3 was found to be a quinone-forming enzyme that produces the coupling substrate, DHK-OH and the final product, ACT. Consequently, the functional assignment of all essential enzymes in the biosynthesis of ACT, one of the best-known model natural products, has been completed. |
