In a complex with RifK, RifL may catalyze the oxidation of UDP-glucose to UDP-3-keto-D-glucose, which would then be used by RifK to produce UDP-kanosamine. Is not able to use dTDP-glucose as substrate. NAD(+) + UDP-alpha-D-glucose = H(+) + NADH + UDP-3-oxo-alpha-D-glucose Antibiotic biosynthesis; rifamycin B biosynthesis. Interacts with RifK. Cells lacking this gene are unable to produce rifamycin B, but production can be restored to wild-type levels by supplementation of the culture with 3-amino-5-hydroxybenzoate (AHBA).