Riboflavin kinase and FAD synthase (RK and FADS)

Riboflavin kinase (EC 2.7.1.26) phosphorylates riboflavin to produce FMN using ATP (or, in some archaea, CTP). FAD synthase (EC 2.7.7.2) then adenylates FMN to form FAD, a reaction essential for generating the redox cofactors required by a wide range of cellular enzymes and metabolic pathways. In eukaryotes, these are generally two distinct proteins, while many prokaryotes possess a bifunctional enzyme capable of both activities. Both enzymes are fundamental for maintaining cellular energy production, oxidative stress defense, and biosynthesis of other vitamins/cofactors. Disruption of their function in pathogens may provide a selective therapeutic strategy, which has driven interest in drug development—particularly for FAD synthase as an antibacterial target.

Other names

FlavokinaseATP:riboflavin 5'-phosphotransferaseFMN adenylyltransferaseFADS

Competitive or allosteric inhibition of the catalytic sites to block FMN or FAD production. Depletion of essential flavocoenzymes in pathogens prevents assembly and function of critical flavoenzymes.