title: Membrane-Anchored Cytochrome P450 1A2-Cytochrome b5 Complex Features an X-Shaped Contact between Antiparallel Transmembrane Helices.
abstract: Eukaryotic cytochromes P450 (P450) are membrane-bound enzymes oxidizing a broad spectrum of hydrophobic substrates, including xenobiotics. Protein-protein interactions play a critical role in this process. In particular, the formation of transient complexes of P450 with another protein of the endoplasmic reticulum membrane, cytochrome b5 (cyt b5), dictates catalytic activities of several P450s. To lay a structural foundation for the investigation of these effects, we constructed a model of the membrane-bound full-length human P450 1A2-cyt b5 complex. The model was assembled from several parts using a multiscale modeling approach covering all-atom and coarse-grained molecular dynamics (MD). For soluble P450 1A2-cyt b5 complexes, these simulations yielded three stable binding modes (sAI, sAII, and sB). The membrane-spanning transmembrane domains were reconstituted with the phospholipid bilayer using self-assembly MD. The predicted full-length membrane-bound complexes (mAI and mB) featured a spontaneously formed X-shaped contact between antiparallel transmembrane domains, whereas the mAII mode was found to be unstable in the membrane environment. The mutual position of soluble domains in binding mode mAI was analogous to the sAI complex. Featuring the largest contact area, the least structural flexibility, the shortest electron transfer distance, and the highest number of interprotein salt bridges, mode mAI is the best candidate for the catalytically relevant full-length complex.
authors.affiliation: Department of Biochemistry, Faculty of Science, Charles University in Prague , Albertov 2030, 128 43 Prague 2, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Jeřábek
authors.affiliation: Department of Chemistry and Biochemistry, Loyola University Chicago , 1032 West Sheridan Road, Chicago, Illinois 60660, United States.
authors.forename: Jan
authors.initials: J
authors.lastname: Florián
authors.affiliation: Department of Biochemistry, Faculty of Science, Charles University in Prague , Albertov 2030, 128 43 Prague 2, Czech Republic.|Department of Teaching and Didactics of Chemistry, Faculty of Science, Charles University in Prague , Albertov 3, 128 43 Prague 2, Czech Republic.
authors.forename: Václav
authors.initials: V
authors.lastname: Martínek
mesh_terms: D019388:Cytochrome P-450 CYP1A2 / Q000737:chemistry / Q000378:metabolism*; D015786:Cytochromes b5 / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D000072417:Protein Domains; D017433:Protein Structure, Secondary
chemical_list: D008051:Lipid Bilayers; D010743:Phospholipids; D015786:Cytochromes b5; C504573:CYP1A2 protein, human; D019388:Cytochrome P-450 CYP1A2