TY - JOUR
T1 - A novel electron transfer mechanism suggested by crystallographic studies of mitochondrial cytochrome bc1 complex
AU - Xia, Di
AU - Kim, Hoeon
AU - Yu, Chang An
AU - Yu, Linda
AU - Kachurin, Anatoly
AU - Zhang, Li
AU - Deisenhofer, Johann
PY - 1998
Y1 - 1998
N2 - The crystal structure of bovine mitochondrial cytochrome bc1 complex, an integral membrane protein complex of 11 different subunits with a total molecular mass of 242 kDa, demonstrated a tightly associated dimer consisting of three major regions: a matrix region primarily made of subunits core1, core2, 6, and 9; a transmembrane-helix region of 26 helices in the dimer contributed by cytochrome b, cytochrome c1, the Rieske iron-sulfur protein (ISP), subunits 7, 10, and 11; and an intermembrane-space region composed of extramembrane domains of ISP, cytochrome c1, and subunit 8. The structure also revealed the positions of and distances between irons of prosthetic groups, and two symmetry related cavities in the transmembrane-helix region upon dimerization of the bc1 complex. Extensive crystallographic studies on crystals of bc1 complexed with inhibitors of electron transfer identified binding pockets for both Q(o) and Q(i) site inhibitors. Discrete binding sites for subtypes of Q(o) site inhibitors have been mapped onto the Q(o) binding pocket, and bindings of different subtypes of Q(o) site inhibitors are capable of inducing dramatic conformational changes in the extramembrane domain of ISP. A novel electron transfer mechanism for the bc1 complex consistent with crystallographic observations is discussed.
AB - The crystal structure of bovine mitochondrial cytochrome bc1 complex, an integral membrane protein complex of 11 different subunits with a total molecular mass of 242 kDa, demonstrated a tightly associated dimer consisting of three major regions: a matrix region primarily made of subunits core1, core2, 6, and 9; a transmembrane-helix region of 26 helices in the dimer contributed by cytochrome b, cytochrome c1, the Rieske iron-sulfur protein (ISP), subunits 7, 10, and 11; and an intermembrane-space region composed of extramembrane domains of ISP, cytochrome c1, and subunit 8. The structure also revealed the positions of and distances between irons of prosthetic groups, and two symmetry related cavities in the transmembrane-helix region upon dimerization of the bc1 complex. Extensive crystallographic studies on crystals of bc1 complexed with inhibitors of electron transfer identified binding pockets for both Q(o) and Q(i) site inhibitors. Discrete binding sites for subtypes of Q(o) site inhibitors have been mapped onto the Q(o) binding pocket, and bindings of different subtypes of Q(o) site inhibitors are capable of inducing dramatic conformational changes in the extramembrane domain of ISP. A novel electron transfer mechanism for the bc1 complex consistent with crystallographic observations is discussed.
KW - Conformational change
KW - Electron transfer
KW - Inhibitor
KW - Structure
KW - bc1 complex
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U2 - 10.1139/bcb-76-5-673
DO - 10.1139/bcb-76-5-673
M3 - Article
C2 - 10353699
AN - SCOPUS:0032451832
SN - 0829-8211
VL - 76
SP - 673
EP - 679
JO - Biochemistry and Cell Biology
JF - Biochemistry and Cell Biology
IS - 5
ER -