TY - JOUR
T1 - Inhibitor binding changes domain mobility in the iron-sulfur protein of the mitochondrial bc1 complex from bovine heart
AU - Kim, Hoeon
AU - Xia, Di
AU - Yu, Chang An
AU - Xia, Jia Zhi
AU - Kachurin, Anatoly M.
AU - Zhang, Li
AU - Yu, Linda
AU - Deisenhofer, Johann
PY - 1998/7/7
Y1 - 1998/7/7
N2 - We have analyzed crystal structures of cytochrome bc1 complexes with electron transfer inhibitors bound to the ubiquinone binding pockets Q(i) and/or Q(o) in the cytochrome b subunit. The presence or absence of the Q(i) inhibitor antimycin A did not affect the binding of the Q(o) inhibitors. Different subtypes of Q(o) inhibitors had dramatically different effects on the mobility of the extramembrane domain of the iron-sulfur protein (ISP): Binding of 5-undecyl-6-hydroxy-4,7-dioxobenzothiazol and stigmatellin (subtype Q(o)-II and Q(o)-III, respectively) led to a fixation of the ISP domain on the surface of cytochrome b, whereas binding of myxothiazol and methoxyacrylate-stilbene (subtype Q(o)-I) favored release of this domain. The native structure has an empty Q(o) pocket and is intermediate between these extremes. On the basis of these observations we propose a model of quinone oxidation in the bc1 complex, which incorporates fixed and loose states of the ISP as features important for electron transfer and, possibly, also proton transport.
AB - We have analyzed crystal structures of cytochrome bc1 complexes with electron transfer inhibitors bound to the ubiquinone binding pockets Q(i) and/or Q(o) in the cytochrome b subunit. The presence or absence of the Q(i) inhibitor antimycin A did not affect the binding of the Q(o) inhibitors. Different subtypes of Q(o) inhibitors had dramatically different effects on the mobility of the extramembrane domain of the iron-sulfur protein (ISP): Binding of 5-undecyl-6-hydroxy-4,7-dioxobenzothiazol and stigmatellin (subtype Q(o)-II and Q(o)-III, respectively) led to a fixation of the ISP domain on the surface of cytochrome b, whereas binding of myxothiazol and methoxyacrylate-stilbene (subtype Q(o)-I) favored release of this domain. The native structure has an empty Q(o) pocket and is intermediate between these extremes. On the basis of these observations we propose a model of quinone oxidation in the bc1 complex, which incorporates fixed and loose states of the ISP as features important for electron transfer and, possibly, also proton transport.
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U2 - 10.1073/pnas.95.14.8026
DO - 10.1073/pnas.95.14.8026
M3 - Article
C2 - 9653134
AN - SCOPUS:0032493297
SN - 0027-8424
VL - 95
SP - 8026
EP - 8033
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 14
ER -