The invention relates to composition and methods for expressing UDP-GlcNAc 2-Epimerase/ManNAc Kinase enzyme (GNE) in a living organism. In preferred embodiments, the invention relates to treating disease condition that involves use of therapeutically effective amount of a composition described herein.

The present invention is in the technical field of synthetic biology and metabolic engineering. More particularly, the present invention is in the technical field of metabolically engineered cells and use of said cells in a cultivation, preferably fermentation. The present invention describes a metabolically engineered cell and a method by cultivation, preferably fermentation, with said cell for production of a bioproduct. More specifically, the present invention describes a metabolically engineered cell and a method by cultivation, preferably fermentation, with said cell for production of an N-acetylneuraminic acid (Neu(n)Ac)-containing compound, wherein (n) is 4, 5, 7, 8 or 9 or a combination thereof. The metabolically engineered cell comprises a pathway for production of said Neu(n)Ac-containing compound and is modified in the expression or activity of at least one NeuNAc synthase according to the present invention. Furthermore, the present invention provides for purification of said Neu(n)Ac-containing compound from the cultivation.

Mammalian milk oligosaccharides (MMO) are produced in plants engineered to express recombinant MMO biosynthetic pathways.