Identification of two segments of the γ subunit of ATP synthase responsible for the different affinities of the catalytic nucleotide-binding sites

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dc.contributor.authorMnatsakanyan, Nelli
dc.contributor.authorLi, Yunxiang
dc.contributor.authorWeber, Joachim
dc.creator.orcidhttps://orcid.org/0000-0001-8035-4690
dc.date.accessioned2023-03-29T20:44:25Z
dc.date.available2023-03-29T20:44:25Z
dc.date.issued2019
dc.description.abstractATP synthase uses a rotary mechanism to couple transmembrane proton translocation to ATP synthesis and hydrolysis, which occur at the catalytic sites in the β subunits. In the presence of Mg2+, the three catalytic sites of ATP synthase have vastly different affinities for nucleotides, and the position of the central γ subunit determines which site has high, medium, or low affinity. Affinity differences and their changes as rotation progresses underpin the ATP synthase catalytic mechanism. Here, we used a series of variants with up to 45- and 60-residue-long truncations of the N- and C-terminal helices of the γ subunit, respectively, to identify the segment(s) responsible for the affinity differences of the catalytic sites. We found that each helix carries an affinity-determining segment of ∼10 residues. Our findings suggest that the affinity regulation by these segments is transmitted to the catalytic sites by the DELSEED loop in the C-terminal domain of the β subunits. For the N-terminal truncation variants, presence of the affinity-determining segment and therefore emergence of a high-affinity binding site resulted in WT-like catalytic activity. At the C terminus, additional residues outside of the affinity-determining segment were required for optimal enzymatic activity. Alanine substitutions revealed that the affinity changes of the catalytic sites required no specific interactions between amino acid side chains in the γ and α3β3 subunits but were caused by the presence of the helices themselves. Our findings help unravel the molecular basis for the affinity changes of the catalytic sites during ATP synthase rotation.en_US
dc.identifier.citationThis is the published version of an article that is available at https://doi.org/10.1074/jbc.ra118.002504. Recommended citation: Mnatsakanyan, N., Li, Y., & Weber, J. (2019). Identification of two segments of the γ subunit of ATP synthase responsible for the different affinities of the catalytic nucleotide-binding sites. Journal of Biological Chemistry, 294(4), 1152–1160. This item has been deposited in accordance with publisher copyright and licensing terms and with the author’s permission.en_US
dc.identifier.urihttps://hdl.handle.net/11274/14763
dc.identifier.urihttps://doi.org/10.1074/jbc.ra118.002504
dc.language.isoen_USen_US
dc.publisherAmerican Society for Biochemistry and Molecular Biologyen_US
dc.rights.licenseCC BY-NC-ND
dc.subjectATP synthaseen_US
dc.subjectEnzyme mechanismen_US
dc.subjectATPaseen_US
dc.subjectBioenergeticsen_US
dc.subjectEnzyme catalysisen_US
dc.subjectLigand-binding proteinen_US
dc.subjectConformational changeen_US
dc.subjectOxidative phosphorylationen_US
dc.subjectProton translocationen_US
dc.titleIdentification of two segments of the γ subunit of ATP synthase responsible for the different affinities of the catalytic nucleotide-binding sitesen_US
dc.typeArticleen_US

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