The
b
Subunit of
Escherichia coli
ATP Synthase |
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Authors: | Stanley D Dunn Matthew Revington Daniel J Cipriano Brian H Shilton |
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Institution: | (1) Department of Biochemistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada;(2) Department of Biochemistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada |
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Abstract: | The b subunit of ATP synthase is a major component of the second stalk connecting the F1and F0 sectors of the enzyme and is essential for normal assembly and function. The156-residue b subunit of the Escherichia coli ATP synthase has been investigated extensivelythrough mutagenesis, deletion analysis, and biophysical characterization. The two copies ofb exist as a highly extended, helical dimer extending from the membrane to near the top ofF1, where they interact with the subunit. The sequence has been divided into four domains:the N-terminal membrane-spanning domain, the tether domain, the dimerization domain, andthe C-terminal -binding domain. The dimerization domain, contained within residues 60–122,has many properties of a coiled-coil, while the -binding domain is more globular. Sites ofcrosslinking between b and the a, , , and subunits of ATP synthase have been identified,and the functional significance of these interactions is under investigation. The b dimer mayserve as an elastic element during rotational catalysis in the enzyme, but also directly influencesthe catalytic sites, suggesting a more active role in coupling. |
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Keywords: | ATP synthase second stalk b subunit stator rotational catalysis coiled-coil |
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