Interdomain communication in calcium pump as revealed in the crystal structures with transmembrane inhibitors
Interdomain communication in calcium pump as revealed in the crystal structures with transmembrane inhibitors
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DOI：
10.1073/pnas.0700979104
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发表时间：
2007-04-03
影响因子：
11.1
通讯作者：
Toyoshima, Chikashi
中科院分区：
文献类型：
--
作者：
Takahashi, Mihoko;Kondou, Youhei;Toyoshima, Chikashi
骨骼肌肌浆网Ca ~（2+）-ATP酶是一个由ATP驱动的Ca ~（2+）泵，由3个胞浆区和10个跨膜螺旋组成。在没有Ca 2+的情况下，三个胞质结构域聚集形成一个紧凑的头部，但ATP酶在没有抑制剂的情况下是不稳定的。在这里，我们描述的晶体结构的Ca 2 +-ATP酶的情况下，Ca 2+稳定的环匹阿尼酸单独和与其他抑制剂的组合。环匹阿尼酸位于蛋白质的跨膜区，靠近细胞质表面。结合位点与2，5-二叔丁基-1，4-二羟基苯的结合位点部分重叠，但与毒胡萝卜素的结合位点分开。整体结构与用毒胡萝卜素稳定的结构显著不同：细胞质头部更加直立，跨膜螺旋M1-M4重排。环匹阿尼酸主要改变M1'螺旋的位置，从而改变M2和M4，然后改变M5。因为M5被整合到磷酸化结构域中，所以整个细胞质头部移动。这些结构变化显示了跨膜结构域中的事件如何被传递到胞质结构域，尽管它们之间存在灵活的连接。他们还表明，Ca 2 +-ATP酶具有相当大的可塑性，即使固定的跨膜抑制剂，大概是为了适应热波动。
Ca2+-ATPase of skeletal muscle sarcoplasmic reticulum is an ATP-driven Ca2+ pump consisting of three cytoplasmic domains and 10 transmembrane helices. In the absence of Ca2+, the three cytoplasmic domains gather to form a compact headpiece, but the ATPase is unstable without an inhibitor. Here we describe the crystal structures of Ca2+-ATPase in the absence of Ca2+ stabilized with cyclopiazonic acid alone and in combination with other inhibitors. Cyclopiazonic acid is located in the transmembrane region of the protein near the cytoplasmic surface. The binding site partially overlaps with that of 2,5-di-tert-butyl-1,4-dihydroxybenzene but is separate from that of thapsigargin. The overall structure is significantly different from that stabilized with thapsigargin: The cytoplasmic headpiece is more upright, and the transmembrane helices M1-M4 are rearranged. Cyclopiazonic acid primarily alters the position of the M1' helix and thereby M2 and M4 and then M5. Because M5 is integrated into the phosphorylation domain, the whole cytoplasmic headpiece moves. These structural changes show how an event in the transmembrane domain can be transmitted to the cytoplasmic domain despite flexible links between them. They also reveal that Ca2+-ATPase has considerable plasticity even when fixed by a transmembrane inhibitor, presumably to accommodate thermal fluctuations.