Mutations of human cytochrome P450 reductase differentially modulate heme oxygenase-1 activity and oligomerization
| Autor: | Satya Prakash Panda, Wayne L. Backes, Karen McCammon, Warren J. Huber, Pavel Martásek, Bettie Sue Siler Masters, J. Patrick Connick, Christopher C. Marohnic, James R. Reed |
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| Rok vydání: | 2011 |
| Předmět: |
Flavin adenine dinucleotide
Oxidoreductases Acting on CH-CH Group Donors Oxygenase Flavin Mononucleotide Bilirubin Biliverdin reductase Mutation Missense Biophysics Flavin mononucleotide Heme Reductase Biochemistry Article Heme oxygenase chemistry.chemical_compound chemistry Multienzyme Complexes Flavin-Adenine Dinucleotide Humans Protein Multimerization Molecular Biology Heme Oxygenase-1 NADPH-Ferrihemoprotein Reductase |
| Zdroj: | Archives of Biochemistry and Biophysics. 513:42-50 |
| ISSN: | 0003-9861 |
| DOI: | 10.1016/j.abb.2011.06.008 |
| Popis: | Genetic variations in POR, encoding NADPH-cytochrome P450 oxidoreductase (CYPOR), can diminish the function of numerous cytochromes P450, and also have the potential to block degradation of heme by heme oxygenase-I (HO-1). Purified full-length human CYPOR, HO-1, and biliverdin reductase were reconstituted in lipid vesicles and assayed for NADPH-dependent conversion of heme to bilirubin. Naturally-occurring human CYPOR variants queried were: WT, A115V, Y181D, P228L, M263V, A287P, R457H, Y459H, and V492E. All CYPOR variants exhibited decreased bilirubin production relative to WT, with a lower apparent affinity of the CYPOR∙HO-1 complex than WT. Addition of FMN or FAD partially restored the activities of Y181D, Y459H, and V492E. When mixed with WT CYPOR, only the Y181D CYPOR variant inhibited heme degradation by sequestering HO-1, whereas Y459H and V492E were unable to inhibit HO-1 activity suggesting that CYPOR variants might have differential binding affinities with redox partners. Titrating the CYPOR-HO-1 complex revealed that the optimal CYPOR:HO-1 ratio for activity was 1:2, lending evidence in support of productive HO-1 oligomerization, with higher ratios of CYPOR:HO-1 showing decreased activity. In conclusion, human POR mutations, shown to impact P450 activities, also result in varying degrees of diminished HO-1 activity, which may further complicate CYPOR deficiency. |
| Databáze: | OpenAIRE |
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