Regulation of the expression of phosphoenolpyruvate?:?carbohydrate phosphotransferase system (PTS) genes in Corynebacterium glutamicum R

摘要

The phosphoenolpyruvate?:?carbohydrate phosphotransferase system (PTS) catalyses the transport of carbohydrates by coupling carbohydrate translocation and phosphorylation. In Corynebacterium glutamicum R, the genes ptsH and ptsI encode general components of the PTS, and genes ptsF, ptsS and ptsG each encode fructose-, sucrose- and glucose-specific components of the PTS, respectively. In this study, we examined the mRNA levels of the pts genes in the presence or absence of PTS sugars. Glucose elevated the expression of ptsG, ptsH and ptsI genes, whereas fructose and sucrose induced the expression of all the pts genes examined, i.e. ptsF, -S, -G, -H and -I. We determined the transcriptional start sites of the pts genes and found that these promoters were activated in the presence of fructose. Disruption of fruR, which is a deoxyribonucleoside repressor (DeoR)-type transcriptional regulator co-transcribed with ptsF, resulted in enhanced induction of the fructose-pts operon, ptsI, and ptsH expression in response to fructose, indicating that FruR attenuates the induction of ptsI, ptsH and fructose-pts by fructose.