ThebSubunit ofEscherichia coliATP Synthase

Publisher Website
Google Scholar
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 δ subunit. The sequence has been divided into four domains:the N-terminal membrane-spanning domain, the tether domain, the dimerization domain, andthe C-terminal δ-binding domain. The dimerization domain, contained within residues 60–122,has many properties of a coiled-coil, while the δ-binding domain is more globular. Sites ofcrosslinking between b and the a, α, β, and δ 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.