Heterologous expression of Escherichia coli ppsA (phosphoenolpyruvate synthetase) and galU (UDP-glucose pyrophosphorylase) genes in Corynebacterium glutamicum, and its impact on trehalose synthesis.
Trehalose is a disaccharide with a wide range of applications in the food industry. We recently proposed a strategy for trehalose production based on a Corynebacterium glutamicum strain expressing the Escherichia coli enzyme UDP-glucose pyrophosphorylase (GalU). Biochemical network analysis suggest a further bottleneck for trehalose synthesis resulting from the coupling of phosphotransferase (PTS) mediated glucose uptake, and glucose catabolism in C. glutamicum. To overcome this coupling, we propose the expression of E. coli phosphoenolpyruvate synthetase (PpsA), in addition to GalU expression, in C. glutamicum. Although GalU expression improved trehalose synthesis in C. glutamicum, the simultaneous expression of GalU and PpsA did not result in a further increase in trehalose yield, but resulted in an increased catabolic rate of glucose, which could be ascribed to the operation of a futile cycle between phosphoenolpyruvate and pyruvate. The impact of GalU and PpsA expression on polysaccharide content, side product excretion and metabolic fluxes is discussed, as well as alternative ways to decouple glucose uptake and catabolism, in order to increase trehalose yield.
Padilla
Leandro
L
Departamento de Ingeniería Química y Bioprocesos, Escuela de Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile.
Agosin
Eduardo
E
D048230:Corynebacterium glutamicum / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics; D015870:Gene Expression / Q000235:genetics*; D005818:Genetic Engineering / Q000379:methods; D050743:Pyruvate Synthase / Q000096:biosynthesis* / Q000235:genetics; D014199:Trehalose / Q000096:biosynthesis* / Q000235:genetics; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000096:biosynthesis* / Q000235:genetics
D029968:Escherichia coli Proteins; D014199:Trehalose; D050743:Pyruvate Synthase; C506224:ppsA protein, E coli; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; C121039:galU protein, E coli