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Title
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The structure of bovine IF(1), the regulatory subunit of mitochondrial F-ATPase.
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Authors
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E.Cabezón,
M.J.Runswick,
A.G.Leslie,
J.E.Walker.
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Ref.
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EMBO J, 2001,
20,
6990-6996.
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PubMed id
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Abstract
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In mitochondria, the hydrolytic activity of ATP synthase is regulated by an
inhibitor protein, IF(1). Its binding to ATP synthase depends on pH, and below
neutrality, IF(1) is dimeric and forms a stable complex with the enzyme. At
higher pH values, IF(1) forms tetramers and is inactive. In the 2.2 A structure
of the bovine IF(1) described here, the four monomers in the asymmetric unit are
arranged as a dimer of dimers. Monomers form dimers via an antiparallel
alpha-helical coiled coil in the C-terminal region. Dimers are associated into
oligomers and form long fibres in the crystal lattice, via coiled-coil
interactions in the N-terminal and inhibitory regions (residues 14-47).
Therefore, tetramer formation masks the inhibitory region, preventing IF(1)
binding to ATP synthase.
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