The lateral distance between a proton pump and ATP synthase determines the ATP-synthesis rate

• Published in: Scientific reports Vol. 7; no. 1; pp. 2926 - 12
• Main Authors: Sjöholm, Johannes, Bergstrand, Jan, Nilsson, Tobias, Šachl, Radek, Ballmoos, Christoph von, Widengren, Jerker, Brzezinski, Peter
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 07.06.2017; Nature Publishing Group UK; Nature Portfolio
• Subjects: Adenosine Triphosphate - biosynthesis; ATP synthase; Biochemical Phenomena; Biochemistry; Bioenergetics; biokemi; Biophysical chemistry; Cytochrome; Enzyme Activation; Fluorescent indicators; Hydrophobicity; Lipid Bilayers - chemistry; Lipid Bilayers - metabolism; Lipid composition; Membrane biophysics; Models, Biological; Protein Binding; Protein Transport; Proton Pumps - chemistry; Proton Pumps - metabolism; Proton-Translocating ATPases - chemistry; Proton-Translocating ATPases - metabolism; Protons; Spectroscopy
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-02836-4

We have investigated the effect of lipid composition on interactions between cytochrome bo and ATP-synthase, and the ATP-synthesis activity driven by proton pumping. The two proteins were labeled by fluorescent probes and co-reconstituted in large (d ≅ 100 nm) or giant (d ≅ 10 µm) unilamellar lipid vesicles. Interactions were investigated using fluorescence correlation/cross-correlation spectroscopy and the activity was determined by measuring ATP production, driven by electron-proton transfer, as a function of time. We found that conditions that promoted direct interactions between the two proteins in the membrane (higher fraction DOPC lipids or labeling by hydrophobic molecules) correlated with an increased activity. These data indicate that the ATP-synthesis rate increases with decreasing distance between cytochrome bo and the ATP-synthase, and involves proton transfer along the membrane surface. The maximum distance for lateral proton transfer along the surface was found to be ~80 nm.