Identification and investigation of a novel NADP+-dependent secoisolariciresinol dehydrogenase from Isatis indigotica

Cofactors are crucial for the biosynthesis of natural compounds, and cofactor engineering is a useful strategy for enzyme optimization due to its potential to enhance enzyme efficiency. Secoisolariciresinol dehydrogenase (SIRD) was reported to convert secoisolariciresinol into matairesinol in an NAD(+)-dependent reaction. Here, a SIRD designated as IiSIRD2 identified from Isatis indigotica was found to utilize NADP(+) as the cofactor. To explore the structural basis for this unique cofactor preference, model-based structural analysis was carried out, and it was postulated that a variation at the GXGGXG glycine-rich motif of IiSIRD2 alters its cofactor preference. This study paves way for future investigations on SIRD cofactor specificity and cofactor engineering to improve SIRD's catalytic efficiency.

Automated summary

This study identified a SIRD that utilizes NADP(+) as a cofactor and explored the structural basis for this unique cofactor preference. It provides a foundation for future investigations on SIRD cofactor specificity and cofactor engineering.