The coupling factor, F1-ATPase of Escherichia coli (ECF1) contains five different subunits, α, β, γ, δ and ε. Properties of δ-deficient ECF1 have previously been described. F1ATPase containing only the α, β, and γ subunits was prepared from E.coli by passage of δ-deficient ECF1 through an affinity column containing immobilized antibodies to the ε subunit. The δ,ε-deficient enzyme has normal ATPase activity but cannot bind to ECF1-depleted membrane vesicles. Both the δ and ε subunits are required for the binding of δ,ε-deficient ECF1, to membranes and the restoration of oxidative phosphorylation. Either δ or ε will bind to the deficient enzyme to form a four-subunit complex. Neither four-subunit enzyme binds to depleted membranes. The ε subunit, does, however, slightly improve the binding affinity between δ and δ-deficient enzyme suggesting a possible interaction between the two subunits. Neither subunit binds to trypsin-treated ECF1, which contains only the α and β subunits. A role for γ in the binding of ε to F1 is suggested. ε does not bind to ECF1-depleted membranes. Therefore, the in vitro reconstitution of depleted membranes requires an initial complex formation between ε and the rest of ECF1 prior to membrane attachment. Reconstitution experiments indicate that only one ε is required per functional ECF1 molecule.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|State||Published - 1978|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology