Neighbouring subunits of CF0 and between CF1 and CF0 of the soluble chloroplast ATP synthase (CF1‐CF0) as revealed by chemical protein cross‐linking

摘要

>Neighbouring subunits of CF₀ (I–III) and between cf₀ and CF₁ (α-ϵ) of the chloroplast ATP synthase have been examined by cross-linking with Cu-phenanthroline (CuP) and bifunctional, cleavable imidoesters. Imidoesters caused cross-links of α-II, β-I, β-II, γ-II, δ-I and ϵ-III as well as of I₂, I–III, II–III and III₂ of the CF₀ portion. subunits α-II, β-I, β-II, γ-II and I-I are close enough to form intermolecular cystine bridges upon CuP-catalyzed oxidation of sH groups. The results indicate that: (i) mainly interactions of the CF₁ subunits α, β and γ with the CF₀ polypeptides I and II are required for binding of CF₁ to the thylakoid membrane; (ii) subunit ϵ interacts directly with CF₀-III; (iii) the CF₀ portion contains a dimer of subunit I; (iv) subunits α and β appear to be structurally non-equivalent within the protein complex.