Reaction: 3β-hydroxy-9β-pimara-7,15-diene-19,6β-olide + NAD(P)+ = momilactone A + NAD(P)H + H+
For diagram of reaction, click here
Other name(s): momilactone A synthase; OsMAS
Systematic name: 3β-hydroxy-9β-pimara-7,15-diene-19,6β-olide:NAD(P)+ oxidoreductase
Comments: The rice phytoalexin momilactone A is a diterpenoid secondary metabolite that is involved in the defense mechanism of the plant. Momilactone A is produced in response to attack by a pathogen through the perception of elicitor signal molecules such as chitin oligosaccharide, or after exposure to UV irradiation. The enzyme, which catalyzes the last step in the biosynthesis of momilactone A, can use both NAD+ and NADP+ but activity is higher with NAD+ .
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
1. Atawong, A., Hasegawa, M. and Kodama, O. Biosynthesis of rice phytoalexin: enzymatic conversion of 3β-hydroxy-9β-pimara-7,15-dien-19,6β-olide to momilactone A. Biosci. Biotechnol. Biochem. 66 (2002) 566-570. [PMID: 12005050]
2. Shimura, K., Okada, A., Okada, K., Jikumaru, Y., Ko, K.W., Toyomasu, T., Sassa, T., Hasegawa, M., Kodama, O., Shibuya, N., Koga, J., Nojiri, H. and Yamane, H. Identification of a biosynthetic gene cluster in rice for momilactones. J. Biol. Chem. 282 (2007) 34013-34018. [PMID: 17872948]