A new route to dTDP-6-deoxy-l-talose and dTDP-L-rhamnose: dTDP-L-rhamnose 4-epimerase in Burkholderia thailandensis

dTDP-l-rhamnose (dTDP-Rha)-synthesizing dTDP-6-deoxy-l-lyxo-4-hexulose reductase (4-KR) and dTDP-Rha 4-epimerase were characterized from Burkholderia thailandensis E264 by utilizing rmlD_Bth (BTH_I1472) and wbiB_Bth (BTH_I1476), respectively. Incubation of the recombinant WbiB_Bth with RmlA/RmlB/RmlC/Tal, which has previously been shown to generate dTDP-6-deoxy-l-talose (dTDP-6dTal) from α-d-glucose-1-phosphate, dTTP, and NADPH, produced dTDP-Rha. ¹H NMR measurements confirmed that both RmlA/RmlB/RmlC/Tal/WbiB_Bth and RmlA/RmlB/RmlC/RmlD produced dTDP-Rha. WbiB_Bth alone produced dTDP-Rha when incubated with dTDP-6dTal. This is the first report to demonstrate epimerase activity interconverting between dTDP-Rha and dTDP-6dTal.