The regulation of the fucRIKUR operon. The operon is activated by fucR (L-fucose operon activator) and high concentrations of L-fucose. The operon is also inhibited by high concentrations of L-fuculose-1-phosphate. FucR binds to the promoter to aid crp binding to the promoter. When L-fuculose-1-phosphate is present in high concentrations, it binds with fucR and fucR can no longer properly bind to the promoter. The operon has five products: fucP (L-fucose-proton symporter), fucI (L-fucose isomerase), fucK (L-fuculokinase), fucU (L-fucose mutarotase) and fucR. These products are used in the utilization of fucose. Fucose is imported into the cell by fucP. FucI is an enzyme used to turn L-fucose to L-fuculose. FucK is an enzyme used to turn L-fuculose to L-fuculose-1-phosphate. The third final step in fucose utilization is through the enzyme fucA (L-fuculose phosphate aldolase).

Fucose utilization: fucP, fucI, fucK, fucU, fucR, References