This disclosure describes methods for screening heterologous coding regions (e.g., a single gene coding region, and operon, or other gene cluster) for the ability to genetically modify a host cell to perform nonphosphorylative biosynthesis of 2,5-dioxopentanoate and downstream derivatives thereof (e.g., 1,4-butanediol, glutamate, or glutaconate. This disclosure further describes recombinant cells modified to increase nonphosphorylative biosynthesis of 2,5-dioxopentanoate compared to an appropriate control cell (e.g., a wild-type cell or an otherwise genetically-modified cell) and methods of using making and using such recombinant cells. |