Immediate inhibition of sucrose uptake in Corynebacterium glutamicum in response to intracellular glucose-6-phosphate accumulation requires the ptsG encoded EII-permease

Abstract

Corynebacterium glutamicum co-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 of pgi (encodes phosphoglucoisomerase) redirects glucose-driven carbon flux towards pentose phosphate pathway. C. glutamicum {Delta}pgi grows poorly with glucose but has unaffected, good growth with sucrose. However, addition of glucose to sucrose-cultivated C. glutamicum {Delta}pgi immediately arrested growth via inhibition of the EIISuc-mediated sucrose uptake and reduction of ptsS-mRNA amounts. Kinetic analyses revealed that sucrose uptake inhibition in C. glutamicum {Delta}pgi took 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 EIIGlc not 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 strain C. glutamicum {Delta}pgi{Delta}ptsG. These results show that the ptsG-encoded EIIGlc is part of a novel mechanism for perception of intracellular glucose-6-P accumulation and instantaneous inhibition of EIISuc-mediated sucrose uptake in C. 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 for C. glutamicum.\n\nIMPORTANCECoordination of substrate uptake and metabolism are a prerequisite for efficient co-utilization of substrates, a trait typical for the Gram-positive C. glutamicum. Sucrose uptake via the PTS permease EIISuc in 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. glutamicum possesses 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.