3W5H

Ultra-high resolution structure of NADH-cytochrome b5 reductase

Summary for 3W5H

• Entry DOI: 10.2210/pdb3w5h/pdb
• Related: 3W2E 3W2F 3W2G 3W2H 3W2I
• Descriptor: NADH-cytochrome b5 reductase 3, FLAVIN-ADENINE DINUCLEOTIDE, GLYCEROL, ... (4 entities in total)
• Functional Keywords: electron transfer, fad binding, er, oxidoreductase
• Biological source: Sus scrofa (pigs,swine,wild boar)
• Cellular location: Endoplasmic reticulum membrane; Lipid- anchor; Cytoplasmic side (By similarity): P83686
• Total number of polymer chains: 1
• Total formula weight: 32027.60

Authors

Takeda, K.,Ohno, H.,Kosugi, M.,Takaba, K.,Miki, K. (deposition date: 2013-01-30, release date: 2013-07-17, Last modification date: 2024-04-03)

Primary citation

Yamada, M.,Tamada, T.,Takeda, K.,Matsumoto, F.,Ohno, H.,Kosugi, M.,Takaba, K.,Shoyama, Y.,Kimura, S.,Kuroki, R.,Miki, K.
Elucidations of the catalytic cycle of NADH-cytochrome b5 reductase by X-ray crystallography: new insights into regulation of efficient electron transfer
J.Mol.Biol., 425:4295-4306, 2013

PubMed Abstract: NADH-Cytochrome b5 reductase (b5R), a flavoprotein consisting of NADH and flavin adenine dinucleotide (FAD) binding domains, catalyzes electron transfer from the two-electron carrier NADH to the one-electron carrier cytochrome b5 (Cb5). The crystal structures of both the fully reduced form and the oxidized form of porcine liver b5R were determined. In the reduced b5R structure determined at 1.68Å resolution, the relative configuration of the two domains was slightly shifted in comparison with that of the oxidized form. This shift resulted in an increase in the solvent-accessible surface area of FAD and created a new hydrogen-bonding interaction between the N5 atom of the isoalloxazine ring of FAD and the hydroxyl oxygen atom of Thr66, which is considered to be a key residue in the release of a proton from the N5 atom. The isoalloxazine ring of FAD in the reduced form is flat as in the oxidized form and stacked together with the nicotinamide ring of NAD(+). Determination of the oxidized b5R structure, including the hydrogen atoms, determined at 0.78Å resolution revealed the details of a hydrogen-bonding network from the N5 atom of FAD to His49 via Thr66. Both of the reduced and oxidized b5R structures explain how backflow in this catalytic cycle is prevented and the transfer of electrons to one-electron acceptors such as Cb5 is accelerated. Furthermore, crystallographic analysis by the cryo-trapping method suggests that re-oxidation follows a two-step mechanism. These results provide structural insights into the catalytic cycle of b5R.

PubMed: 23831226
DOI: 10.1016/j.jmb.2013.06.010

Experimental method

X-RAY DIFFRACTION (0.78 Å)