Immediate inhibition of sucrose uptake inCorynebacterium glutamicumin response to intracellular glucose-6-phosphate accumulation requires theptsGencoded EII-permease

Abstract

ABSTRACTCorynebacterium glutamicumco-metabolizes most carbon sources, such as glucose and sucrose. Uptake of those sugars by the PTS involves a glucose- and a sucrose-specific permease EIIGlc(ptsG) and EIISuc(ptsS), respectively. Block of glycolysis by deletion ofpgi(encodes phosphoglucoisomerase) redirects glucose-driven carbon flux towards pentose phosphate pathway.C. glutamicumΔpgigrows poorly with glucose but has unaffected, good growth with sucrose. However, addition of glucose to sucrose-cultivatedC. glutamicumΔpgiimmediately arrested growth via inhibition of the EIISuc–mediated sucrose uptake and reduction ofptsS-mRNA amounts. Kinetic analyses revealed that sucrose uptake inhibition inC. glutamicumΔpgitook place within 15 s after glucose addition. We show that inhibition of PTS-mediated sucrose uptake occurs as direct response to glucose-6-P accumulation. Moreover, addition of non-PTS substrates, which are metabolized to glucose-6-P such as maltose or glucose-6-P itself (uptake was enabled by heterologously produced UhpT), led to similar growth and sucrose uptake inhibition as glucose addition. Despite EIIGlcnot being involved in uptake of these substrates, negative effects on sucrose uptake after addition of maltose and glucose-6-P were absent in the EIIGlc–deficient strainC. glutamicumΔpgiΔptsG. These results show that theptsG-encoded EIIGlcis part of a novel mechanism for perception of intracellular glucose-6-P accumulation and instantaneous inhibition of EIISuc-mediated sucrose uptake inC. glutamicum. This novel mode of control of PTS activity by an early glycolytic metabolite probably allows efficient adaptation of sugar uptake to the capacity of the central metabolism during co-metabolization, which is characteristic forC. glutamicum.IMPORTANCECoordination of substrate uptake and metabolism are a prerequisite for efficient co-utilization of substrates, a trait typical for the Gram-positiveC. glutamicum. Sucrose uptake via the PTS permease EIISucin this organism immediately was inhibited in response to intracellular accumulation of the glycolysis intermediate glucose-6-phosphate. This inhibition depends exclusively on the presence but not activity of the PTS permease EIIGluc. Thus,C. glutamicumpossesses a novel, immediate, and PTS-dependent way to control and coordinate both uptake and metabolization of multiple substrates by monitoring of their metabolic levels in the cell. This offers new insights and interesting concepts for a further rational engineering of this industrially important production organism and exemplifies a putative general strategy of bacteria for the coordination of sugar uptake and central metabolism.