Crystal structure of a NADPH-cytochrome P450 oxidoreductase (CYPOR) and heme oxygenase 1 fusion protein implies a conformational change in CYPOR upon NADPH/NADP+binding.
Sugishima, M., Sato, H., Wada, K., Yamamoto, K.(2019) FEBS Lett 593: 868-875
- PubMed: 30883732 
- DOI: https://doi.org/10.1002/1873-3468.13360
- Primary Citation of Related Structures:  
6J79, 6J7A, 6J7I - PubMed Abstract: 
Heme oxygenase-1 (HMOX1) catalyzes heme degradation utilizing reducing equivalents supplied from NADPH-cytochrome P450 reductase (CYPOR). Recently, we determined the complex structure of NADP + -bound open-conformation stabilized CYPOR and heme-HMOX1, but the resolution was limited to 4.3 Å. Here, we determined the crystal structure of the fusion protein of open-conformation stabilized CYPOR and heme-HMOX1 at 3.25 Å resolution. Unexpectedly, no NADP + was bound to this fusion protein in the crystal. Structural comparison of the NADP + -bound complex and the NADP + -free fusion protein suggests that NADP + binding regulates the conformational change in the FAD-binding domain of CYPOR. As a result of this change, the FMN-binding domain of CYPOR approaches heme-bound HMOX1 upon NADP + binding to enhance the electron-transfer efficiency from FMN to heme.
Organizational Affiliation: 
Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Japan.