The Inhibitor Protein (IF1) Promotes Dimerization of the Mitochondrial F1F0-ATP Synthase

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• 作者：José ; J. Garc&iacute ; a ; Edgar Morales-R&iacute ; os ; Paulina Corté ; s-Herná ; ndez ; José ; S. Rodr&iacute ; guez-Zavala
• 刊名：Biochemistry
• 出版年：2006
• 出版时间：October 24, 2006
• 年：2006
• 卷：45
• 期：42
• 页码：12695 - 12703
• 全文大小：404K
• 年卷期：v.45,no.42(October 24, 2006)
• ISSN：1520-4995

文摘

The effect of increased expression or reconstitution of the mitochondrial inhibitor protein (IF₁)on the dimer/monomer ratio (D/M) of the rat liver and bovine heart F₁F₀-ATP synthase was studied. The2-fold increased expression of IF₁ in AS-30D hepatoma mitochondria correlated with a 1.4-fold increasein the D/M ratio of the ATP synthase extracted with digitonin as determined by blue native electrophoresisand averaged densitometry analyses. Removal of IF₁ from rat liver or bovine heart submitochondrialparticles increased the F₁F₀-ATPase activity and decreased the D/M ratio of the ATP synthase.Reconstitution of recombinant IF₁ into submitochondrial particles devoid of IF₁ inhibited the F₁F₀-ATPaseactivity by 90% and restored partially the D/M ratio of the whole F₁F₀ complex as revealed by bluenative electrophoresis and subsequent SDS-PAGE or glycerol density gradient centrifugation. Thus, theinhibitor protein promotes or stabilizes the dimeric form of the intact F₁F₀-ATP synthase. A possiblelocation of the IF₁ protein in the dimeric structure of the rat liver F₁F₀ complex is proposed. Accordingto crystallographic and electron microscopy analyses, dimeric IF₁ could bridge the F₁-F₁ part of the dimericF₁F₀-ATP sythase in the inner mitochondrial membrane.