Engineering of a UDP-Glycosyltransferase for the Efficient Whole-Cell Biosynthesis of Siamenoside I in .

The combination of the insufficient availability and the complex structure of siamenoside I (SI), the sweetest glucoside isolated from to date, limited its use as a natural sweetener. To solve this problem, an improved biocatalyst, UGT-M2, was semi-rationally created by engineering the uridine diphosphate glycosyltransferase UGT94-289-2 from for the monoglucosylation of mogroside IIIE (MG IIIE) to SI. Subsequently, an engineered cell was constructed, which combined UGT-M2 with a UDP-glucose regeneration system to circumvent the need for expensive UDP-glucose to produce SI.

Efficient whole-cell biosynthesis of l-gulose by coupling mannitol-1-dehydrogenase with NADH oxidase.

L-Gulose is a rare aldohexose to serve as a building block for anticancer drug bleomycin and nucleoside-based antivirals. However, preparative inaccessibility and high cost have hindered its pharmaceutical application. Despite a regio- and stereo-selective enzymatic synthesis of l-gulose from d-sorbitol using a variant of NAD-dependent mannitol-1-dehydrogenase from Apium graveolens (mMDH) was explored, low efficiency and productivity caused by NADH accumulation or insufficient amount of NAD limited the practical utility of this process.