A possible role of NADPH-dependent cytochrome P450nor isozyme in glycolysis under denitrifying conditions.
The denitrifying fungus Cylindrocarpon tonkinense contains two isozymes of cytochrome P450nor. One isozyme, P450nor1, uses NADH specifically as its electron donor whereas the other isozyme P450nor2 prefers NADPH to NADH. Here we show that P450nor1 is localized in both cytosol and mitochondria, like P450nor of Fusarium oxysporum, while P450nor2 is exclusively in cytosol. We also found that the addition of glucose as a carbon source to the culture media leads to the production of much more P450nor2 in the fungal cells than a non-fermentable substrate (glycerol or acetate) does. These results suggest that the NADP-dependent pentose phosphate cycle acts predominantly in C. tonkinense as the glycolysis pathway under the denitrifying conditions, which was confirmed by the observation that glucose induced enzyme activities involved in the cycle. These results showed that P450nor2 should act as the electron sink under anaerobic, denitrifying conditions to regenerate NADP+ for the pentose phosphate cycle.
Watsuji
Tomo-o
TO
Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
Takaya
Naoki
N
Nakamura
Akira
A
Shoun
Hirofumi
H
D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics; D015153:Blotting, Western; D002244:Carbon / Q000378:metabolism; D002474:Cell-Free System; D003470:Culture Media; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D006019:Glycolysis / Q000502:physiology*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010427:Pentose Phosphate Pathway / Q000235:genetics / Q000502:physiology; D013347:Subcellular Fractions / Q000201:enzymology
D003470:Culture Media; D007527:Isoenzymes; D002244:Carbon; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; C080610:nitric-oxide reductase (P450); D009584:Nitrogen