5ZLG

Human duodenal cytochrome b (Dcytb) in zinc ion and ascorbate bound form

Summary for 5ZLG

• Entry DOI: 10.2210/pdb5zlg/pdb
• Related: 5ZLE
• Descriptor: Cytochrome b reductase 1, PROTOPORPHYRIN IX CONTAINING FE, ZINC ION, ... (5 entities in total)
• Functional Keywords: electron transport, oxidoreductase
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 1
• Total formula weight: 34012.66

Authors

Ganasen, M.,Togashi, H.,Mauk, G.A.,Shiro, Y.,Sawai, H.,Sugimoto, H. (deposition date: 2018-03-27, release date: 2018-10-31, Last modification date: 2023-11-22)

Primary citation

Ganasen, M.,Togashi, H.,Takeda, H.,Asakura, H.,Tosha, T.,Yamashita, K.,Hirata, K.,Nariai, Y.,Urano, T.,Yuan, X.,Hamza, I.,Mauk, A.G.,Shiro, Y.,Sugimoto, H.,Sawai, H.
Structural basis for promotion of duodenal iron absorption by enteric ferric reductase with ascorbate.
Commun Biol, 1:120-120, 2018

PubMed Abstract: Dietary iron absorption is regulated by duodenal cytochrome (Dcytb), an integral membrane protein that catalyzes reduction of nonheme Fe by electron transfer from ascorbate across the membrane. This step is essential to enable iron uptake by the divalent metal transporter. Here we report the crystallographic structures of human Dcytb and its complex with ascorbate and Zn. Each monomer of the homodimeric protein possesses cytoplasmic and apical heme groups, as well as cytoplasmic and apical ascorbate-binding sites located adjacent to each heme. Zn coordinates to two hydroxyl groups of the apical ascorbate and to a histidine residue. Biochemical analysis indicates that Fe competes with Zn for this binding site. These results provide a structural basis for the mechanism by which Fe uptake is promoted by reducing agents and should facilitate structure-based development of improved agents for absorption of orally administered iron.

PubMed: 30272000
DOI: 10.1038/s42003-018-0121-8

Experimental method

X-RAY DIFFRACTION (2.8 Å)