Structure of Na+,K+-ATPase at 11-A resolution: comparison with Ca2+-ATPase in E1 and E2 states.
Structure of Na+,K+-ATPase at 11-A resolution: comparison with Ca2+-ATPase in E1 and E2 states.
复制标题
11-A 分辨率下的 Na,K -ATP 酶结构：与 E1 和 E2 状态下的 Ca2 -ATP 酶比较。
DOI：
10.1016/s0006-3495(01)76191-7
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发表时间：
2001
影响因子：
3.4
通讯作者：
Stokes,DL
中科院分区：
文献类型：
--
作者：
Rice,WJ;Young,HS;Martin,DW;Sachs,JR;Stokes,DL
Na+,K+-ATP酶是α和β亚基的异二聚体，是离子泵P型ATP酶家族的成员。在这里，我们展示了根据未染色的冷冻水合管状晶体的电子显微照片确定的异二聚体的 11-Å 结构。为了进行这种重建，从盐适应鸭的眶上腺中分离出酶，并在天然膜内结晶。结晶条件将Na+,K+-ATP酶固定在钒酸盐抑制的E2构象中，并且晶体具有p1对称性。观察到大量螺旋对称性，因此通过对来自不同对称性的数据的傅里叶-贝塞尔系数和实空间结构进行平均来计算三维结构。由此产生的结构清楚地揭示了分子的细胞质、跨膜和细胞外区域，其密度分别归因于α和β亚基。整体形状与兔肌浆网Ca2+-ATP酶的E2结构非常相似。对齐这两个结构后，Ca2+-ATPase 的原子坐标与 Na+,K+-ATPase 相匹配，并且几个与图谱不太吻合的柔性表面环与两个泵中不同的序列相关联。然而，细胞质结构域的排列非常相似，表明 Ca2+-ATP 酶假定的 E2 到 E1 构象变化可能适用于 Na+、K+-ATP 酶以及其他 P 型 ATP 酶。
Na+,K+-ATPase is a heterodimer ofαandβsubunits and a member of the P-type ATPase family of ion pumps. Here we present an 11-Å structure of the heterodimer determined from electron micrographs of unstained frozen-hydrated tubular crystals. For this reconstruction, the enzyme was isolated from supraorbital glands of salt-adapted ducks and was crystallized within the native membranes. Crystallization conditions fixed Na+,K+-ATPase in the vanadate-inhibited E2conformation, and the crystals had p1 symmetry. A large number of helical symmetries were observed, so a three-dimensional structure was calculated by averaging both Fourier-Bessel coefficients and real-space structures of data from the different symmetries. The resulting structure clearly reveals cytoplasmic, transmembrane, and extracellular regions of the molecule with densities separately attributable toαandβsubunits. The overall shape bears a remarkable resemblance to the E2structure of rabbit sarcoplasmic reticulum Ca2+-ATPase. After aligning these two structures, atomic coordinates for Ca2+-ATPase were fit to Na+,K+-ATPase, and several flexible surface loops, which fit the map poorly, were associated with sequences that differ in the two pumps. Nevertheless, cytoplasmic domains were very similarly arranged, suggesting that the E2-to-E1conformational change postulated for Ca2+-ATPase probably applies to Na+,K+-ATPase as well as other P-type ATPases.