ATP synthase uses a unique rotary mechanism to couple ATP synthesis and hydrolysis to transmembrane proton translocation. As part of the synthesis mechanism, the torque of the rotor has to be converted into conformational rearrangements of the catalytic binding sites on the stator, to allow synthesis and release of ATP. The gamma subunit of the rotor, which plays a central role in the energy conversion, consists of two long helices inside the central cavity of the stator cylinder, plus a globular portion outside of the cylinder. Here we show that the N-terminal helix alone is able to fulfill the function of full-length gamma in ATP synthesis, as long as it connects to the rest of the rotor. This connection can occur via the epsilon subunit. No direct contact between gamma and the c ring seems to be required. In addition, the results indicate that the epsilon subunit of the rotor exists in two different conformations in ATP synthesis versus hydrolysis.
|Journal||Journal of Biological Chemistry|
|State||Published - Sep 25 2009|