Escherichia coli F1Fo-ATP Synthase with a b/δ Fusion Protein Allows Analysis of the Function of the Individual b Subunits

• Published in: The Journal of biological chemistry Vol. 288; no. 37; pp. 26441 - 26447
• Main Authors: Gajadeera, Chathurada S., Weber, Joachim
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 13.09.2013; American Society for Biochemistry and Molecular Biology
• Subjects: ATP Synthase; Bacterial Proton-Translocating ATPases - metabolism; Bioenergetics; Catalysis; Cell Membrane - metabolism; Enzyme Catalysis; Enzyme Mechanisms; Escherichia coli - enzymology; Escherichia coli Proteins - metabolism; Membrane Proteins; Plasmids - metabolism; Point Mutation; Protein Assembly; Protein Structure, Secondary; Protein Structure, Tertiary; Proton-Translocating ATPases - chemistry; Recombinant Fusion Proteins - metabolism; Enzyme Mechanisms; Membrane Proteins; ATP Synthase; Enzyme Catalysis; Protein Assembly
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M113.503722

The “stator stalk” of F1Fo-ATP synthase is essential for rotational catalysis as it connects the nonrotating portions of the enzyme. In Escherichia coli, the stator stalk consists of two (identical) b subunits and the δ subunit. In mycobacteria, one of the b subunits and the δ subunit are replaced by a b/δ fusion protein; the remaining b subunit is of the shorter b′ type. In the present study, it is shown that it is possible to generate a functional E. coli ATP synthase containing a b/δ fusion protein. This construct allowed the analysis of the roles of the individual b subunits. The full-length b subunit (which in this case is covalently linked to δ in the fusion protein) is responsible for connecting the stalk to the catalytic F1 subcomplex. It is not required for interaction with the membrane-embedded Fo subcomplex, as its transmembrane helix can be removed. Attachment to Fo is the function of the other b subunit which in turn has only a minor (if any at all) role in binding to δ. Also in E. coli the second b subunit can be shortened to a b′ type. Background: The essential “stator stalk” connects the nonrotating portions of F1Fo-ATP synthase. Results: A b/δ fusion protein is functional and allows analyzing the role of the individual b subunits. Conclusion: One of the b subunits is required for binding to F1, the other for binding to Fo. Significance: Understanding the function of the stator stalk is important for understanding the mechanism of ATP synthase.