EFFECT OF PQQ GLUCOSE-DEHYDROGENASE OVEREXPRESSION IN ESCHERICHIA-COLI ON SUGAR-DEPENDENT RESPIRATION

Pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) was overexpres sed in Escherichia coli, and its impact on sugar-dependent respiration was investigated. Sugar-dependent respiration patterns under PQQGDH o verexpression can be devided into two types. The first type involves D -glucose and D-mannose, which are utilized by the phosphotransferase s ystem (PTS) and are also the substrates of PQQGDH. As a result of PQQG DH overexpression, the apparent K-m value of sugar-dependent respirati on shifted to higher concentration compared with E. coli parental cell s. The second type included D-xylose and D-galactose, which are the su bstrates of PQQGDH, but not the PTS sugars. PQQGDH overexpressing cell s showed much higher respiration than parental cells. These results su ggested that PQQGDH overexpression may alter sugar utilization prefere nces in E. coli, suggesting further possible applications in metabolic engineering for carbon source utilization.