Identification of a second beta-glucoside phosphoenolpyruvate: carbohydrate phosphotransferase system in Corynebacterium glutamicum R.

The phosphoenolpyruvate : carbohydrate phosphotransferase system (PTS) catalyses carbohydrate transport by coupling it to phosphorylation. Previously, we reported a Corynebacterium glutamicum R beta-glucoside PTS encoded by bglF. Here we report that C. glutamicum R contains an additional beta-glucoside PTS gene, bglF2, organized in a cluster with a putative phospho-beta-glucosidase gene, bglA2, and a putative antiterminator, bglG2. While single gene disruption strains of either bglF or bglF2 were able to utilize salicin or arbutin as sole carbon sources, a double disruption strain exhibited defects in utilization of both carbon sources. Expression of both bglF and bglF2 was induced in the presence of either salicin or arbutin, although disruption of bglG2 affected only bglF2 expression. Moreover, in the presence of either salicin or arbutin, glucose completely repressed the expression of bglF but only slightly repressed that of bglF2. We conclude that BglF and BglF2 have a redundant role in beta-glucoside transport even though the catabolite repression control of their encoding genes is different. We also show that expression of both bglF and bglF2 requires the general PTS.