A revised biosynthetic pathway for the cofactor F420in bacteria

Cofactor F 420 plays critical roles in primary and secondary metabolism in a range of bacteria and archaea as a low-potential hydride transfer agent. It mediates a variety of important redox transformations involved in bacterial persistence, antibiotic biosynthesis, pro-drug activation and methanogenesis. However, the biosynthetic pathway for F 420 has not been fully eluci-dated: neither the enzyme that generates the putative intermediate 2-phospho- L -lactate, nor the function of the FMN-binding C-terminal domain of the γ-glutamyl ligase (FbiB) in bacteria are known. Here we show that the guanylyltransferases FbiD and CofC accept phosphoenolpyruvate, rather than 2-phospho- L -lactate, as their substrate, leading to the formation of the previously uncharacterized intermediate, dehydro-F 420 -0. The C-terminal domain of FbiB then utilizes FMNH2 to reduce dehydro-F 420 -0, which produces mature F 420 species when combined with the γ-glutamyl ligase activity of the N-terminal domain. This new insight has allowed the heterologous expression F 420 from a recombinant F 420 biosynthetic pathway in Escherichia coli .