Construction of an Alternative NAD De Novo Biosynthesis Pathway.

Nicotinamide adenine dinucleotide (NAD) is a life essential molecule involved in versatile biological processes. To date, only two de novo biosynthetic routes to NAD are described, both of which start from a proteinogenic amino acid and are tightly controlled. Here, a de novo quinolinic acid pathway starting from chorismate, which provides an alternative route (named as the C3N pathway) to NAD biosynthesis, is established. Significantly, the C3N pathway yields extremely high cellular concentrations of NAD(H) in . Its utility in cofactor engineering is demonstrated by introducing the four-gene C3N module to cell factories to achieve higher production of 2,5-dimethylpyrazine and develop an efficient C3N-based whole-cell bioconversion system for preparing chiral amines. The wide distribution and abundance of chorismate in most kingdoms of life implies a general utility of the C3N pathway for modulating cellular levels of NAD(H) in versatile organisms.