Distinct physiological roles of two membrane-bound dehydrogenases responsible for D-sorbitol oxidation in Gluconobacter frateurii.
Two different membrane-bound enzymes oxidizing D-sorbitol are found in Gluconobacter frateurii THD32: pyroloquinoline quinone-dependent glycerol dehydrogenase (PQQ-GLDH) and FAD-dependent D-sorbitol dehydrogenase (FAD-SLDH). In this study, FAD-SLDH appeared to be induced by L-sorbose. A mutant defective in both enzymes grew as well as the wild-type strain did, indicating that both enzymes are dispensable for growth on D-sorbitol. The strain defective in PQQ-GLDH exhibited delayed L-sorbose production, and lower accumulation of it, corresponding to decreased oxidase activity for D-sorbitol in spite of high D-sorbitol dehydrogenase activity, was observed. In the mutant strain defective in PQQ-GLDH, oxidase activity with D-sorbitol was much more resistant to cyanide, and the H(+)/O ratio was lower than in either the wild-type strain or the mutant strain defective in FAD-SLDH. These results suggest that PQQ-GLDH connects efficiently to cytochrome bo(3) terminal oxidase and that it plays a major role in L-sorbose production. On the other hand, FAD-SLDH linked preferably to the cyanide-insensitive terminal oxidase, CIO.
Soemphol
Wichai
W
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan.
Adachi
Osao
O
Matsushita
Kazunobu
K
Toyama
Hirohide
H
D003576:Electron Transport Complex IV / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide; D020576:Gluconobacter / Q000201:enzymology* / Q000254:growth & development; D007700:Kinetics; D008565:Membrane Proteins; D009154:Mutation; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology; D045542:PQQ Cofactor; D013012:Sorbitol / Q000378:metabolism*; D013401:Sugar Alcohol Dehydrogenases
D008565:Membrane Proteins; D005182:Flavin-Adenine Dinucleotide; D013012:Sorbitol; D045542:PQQ Cofactor; D010088:Oxidoreductases; D013401:Sugar Alcohol Dehydrogenases; C020672:glycerol dehydrogenase; C038862:cytochrome o oxidase; D003576:Electron Transport Complex IV