Shilton B, Svergun D I, Volkov V V, Koch M H, Cusack S, Economou A
Institute of Molecular Biology and Biotechnology and Department of Biology, University of Crete, Iraklio, Greece.
FEBS Lett. 1998 Oct 2;436(2):277-82. doi: 10.1016/s0014-5793(98)01141-7.
SecA shape and conformational flexibility in solution were studied by small angle X-ray scattering. Dimeric SecA is a very elongated molecule, 15 nm long and 8 nm wide. SecA is therefore four times as long as the membrane is wide. The two globular protomers are distinctly separated and share limited surface of intermolecular contacts. ATP, ADP or adenylyl-imidodiphosphate (AMP-PNP) binding does not alter the SecA radius of gyration. A SecA mutant that catalyzes multiple rounds of ATP hydrolysis does not undergo conformational changes detectable by small angle X-ray scattering (SAXS). We conclude that SecA conformational alterations observed biochemically during nucleotide interaction are only small-scale and localized. The ramifications of these findings on SecA/SecYEG interaction are discussed.
通过小角X射线散射研究了溶液中SecA的形状和构象灵活性。二聚体SecA是一种非常细长的分子，长15纳米，宽8纳米。因此，SecA的长度是膜宽度的四倍。两个球状原体明显分开，分子间接触的表面有限。ATP、ADP或腺苷酰亚胺二磷酸（AMP-PNP）结合不会改变SecA的回转半径。催化多轮ATP水解的SecA突变体不会发生小角X射线散射（SAXS）可检测到的构象变化。我们得出结论，在核苷酸相互作用过程中通过生化方法观察到的SecA构象改变只是小规模的和局部的。讨论了这些发现对SecA/SecYEG相互作用的影响。
