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Winding and unwinding ATP synthase

ATP synthase turns one way to make ATP and the other to break it down. Börsch

Like a revolving door, bacterial ATP synthase turns two ways, according to Manuel Diez, Michael Börsch (Universität Stuttgart, Germany), and colleagues. One direction makes ATP, whereas the other breaks it down.

ATP synthase is a two-component nanomotor. One part of the enzyme (F₀) lies within the lipid bilayer and translocates protons across the membrane, whereas the other (F₁) makes or breaks ATP. Recent studies have shown that each portion contains a subunit that turns within the rest of the protein framework, thus giving ATP synthase a reputation as a rotor. F₁ rotation had been best shown during ATP hydrolysis, because the microscopy methods used needed soluble protein, but the enzyme requires a proton gradient across a membrane to make ATP.

To solve this problem, the German group used fluorescence resonance energy transfer to study the protein within liposomes, thus allowing them to create a proton gradient. In ATP synthesis mode, the enzyme adopted three sequential positions—similar to the 120° steps seen during hydrolysis with microscopy methods. However, the direction of rotation was opposite to that of hydrolysis. F₀ is thought to rotate smoothly during proton translocation, so researchers next need to determine how that is translated to discrete steps in F₁. Börsch also wonders how cellular conditions toggle the switch from synthesis to hydrolysis and back again.

Reference:

Diez, M., et al. 2004. Nat. Struct. Biol. 11:135–141.

Nicole LeBrasseur

lebrasn{at}rockefeller.edu

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This Article Full Text (PDF, 458K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by LeBrasseur, N. Search for Related Content PubMed Articles by LeBrasseur, N. Social Bookmarking                            What's this?