Rotary ATPases are ubiquitous molecular rotary motors that couple the translocation of protons through membranes to the synthesis or hydrolysis of ATP and are thus central to biological energy conversion. F-type ATP synthases use energy stored in transmembrane proton gradients to synthesise the biological energy carrier ATP from ADP and inorganic phosphate. The evolutionary related V-type ATPases operate in reverse by utilising energy derived from ATP hydrolysis to build up transmembrane ion gradients thereby enabling transport processes across membranes. While chloroplast and most eubacterial rotary ATPases are of the F-type, some eubacteria and all known archaea have ATPases of the A-type, which are close homologues of V-ATPases. A-ATPases are simpler in design than their eukaryotic counterparts, but are more versatile in that they can operate in both directions in dependence of their cellular environment (1).
We are using a combination of X-ray structure analysis, electron microscopy and mass spectrometry to obtain a pseudo-atomic model of an A-ATPase (2, 3). In addition, X-ray structures in different conformations along with normal mode analysis suggest a greater dynamics of the intact complex than previously envisioned and this is likely to have implications on cooperativity and regulation of intact rotary ATPases (4, 5).
1. Stewart et al. BioArchitecture 3 (2013)
2. Zhou, et al. Science 334, 380-385 (2011)
3. Lee, et al. Nat. Struct. Mol. Biol. 17, 373-378 (2010)
4. Stewart, et al. Nature Communications 3, 687 (2012)
5. Stewart et al. Current Opinion Structural Biology 25, 40-48 (2014)