Carbajo Rodrigo J, Kellas Fiona A, Runswick Michael J, Montgomery Martin G, Walker John E, Neuhaus David
MRC Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, UK.
J Mol Biol. 2005 Aug 26;351(4):824-38. doi: 10.1016/j.jmb.2005.06.012.
The peripheral stalk of ATP synthase holds the alpha3beta3 catalytic subcomplex stationary against the torque of the rotating central stalk. In bovine mitochondria, the N-terminal domain of the oligomycin sensitivity conferral protein (OSCP-NT; residues 1-120) anchors one end of the peripheral stalk to the N-terminal tails of one or more alpha-subunits of the F1 subcomplex. Here we present the solution structure of OSCP-NT and an NMR titration study of its interaction with peptides representing N-terminal tails of F1 alpha-subunits. The structure comprises a bundle of six alpha-helices, and its interaction site contains adjoining hydrophobic surfaces of helices 1 and 5; residues in the region 1-8 of the alpha-subunit are essential for the interaction. The OSCP-NT is similar to the N-terminal domain of the delta-subunit from Escherichia coli ATP synthase (delta-NT), except that their surface charges differ (basic and acidic, respectively). As the charges of the adjacent crown regions in their alpha3beta3 complexes are similar, the OSCP-NT and delta-NT probably do not contact the crowns extensively. The N-terminal tails of alpha-subunit tails are probably alpha-helical, and so this interface, which is essential for the rotary mechanism of the enzyme, appears to consist of helix-helix interactions.
ATP合酶的外周柄使α3β3催化亚复合体保持固定，以抵抗旋转中心柄产生的扭矩。在牛线粒体中，寡霉素敏感性赋予蛋白的N端结构域（OSCP-NT；第1至120位氨基酸残基）将外周柄的一端锚定到F1亚复合体一个或多个α亚基的N端尾部。在此，我们展示了OSCP-NT的溶液结构及其与代表F1α亚基N端尾部的肽段相互作用的核磁共振滴定研究。该结构由一束六个α螺旋组成，其相互作用位点包含螺旋1和螺旋5相邻的疏水表面；α亚基第1至8位区域的氨基酸残基对于这种相互作用至关重要。OSCP-NT与来自大肠杆菌ATP合酶的δ亚基的N端结构域（δ-NT）相似，只是它们的表面电荷不同（分别为碱性和酸性）。由于它们α3β3复合体中相邻冠区的电荷相似，OSCP-NT和δ-NT可能不会与冠区广泛接触。α亚基尾部的N端尾部可能是α螺旋结构，因此这个对于酶的旋转机制至关重要的界面似乎由螺旋-螺旋相互作用组成。
