Modeling a dehalogenase fold into the 8-A density map for Ca(2+)-ATPase defines a new domain structure.
Modeling a dehalogenase fold into the 8-A density map for Ca(2+)-ATPase defines a new domain structure.
复制标题
将脱卤素酶折叠建模为 Ca(2 )-ATPase 的 8-A 密度图，定义了新的结构域结构。
DOI：
10.1016/s0006-3495(00)76727-0
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发表时间：
2000
影响因子：
3.4
通讯作者：
Green,NM
中科院分区：
文献类型：
--
作者：
Stokes,DL;Green,NM
P型泵大家族的成员使用主动运输来维持各种阳离子跨细胞膜的梯度。最近的两个P-型泵在8-kDa分辨率的结构揭示了跨膜螺旋的排列，但不足以揭示胞质结构域的架构。然而，最近的建议，一个超家族的水解酶的结构同源性提供了一个新的基础，这些领域的建模。在目前的工作中，我们已经扩大了超家族的序列比较和划定的结构域中的8-巯基密度图的Ca 2 +-ATP酶。同源性表明一个新的结构域的Ca 2 +-ATP酶，特别是，磷酸化结构域采用罗斯曼折叠。因此，L-2卤酸脱卤酶的原子结构与Ca ~（2+）-ATP酶的相关结构域相吻合。由此产生的模型表明，存在两个ATP位点在两个域之间的接口。基于这个新的模型，我们能够调和催化结构域内的诱变和化学交联的许多结果。此外，我们还利用该模型预测了Mg·ATP结合位点的构型。基于这一预测，我们提出了一种机制，涉及Mg 2+配体的变化，启动域运动的离子转运ATP水解的耦合站点。
Members of the large family of P-type pumps use active transport to maintain gradients of a wide variety of cations across cellular membranes. Recent structures of two P-type pumps at 8-Å resolution have revealed the arrangement of transmembrane helices but were insufficient to reveal the architecture of the cytoplasmic domains. However, recent proposals of a structural homology with a superfamily of hydrolases offer a new basis for modeling these domains. In the current work, we have extended the sequence comparison for the superfamily and delineated domains in the 8-Å density map of Ca2+-ATPase. The homology suggests a new domain structure for Ca2+-ATPase and, specifically, that the phosphorylation domain adopts a Rossman fold. Accordingly, the atomic structure of L-2 haloacid dehalogenase has been fitted into the relevant domain of Ca2+-ATPase. The resulting model suggests the existence of two ATP sites at the interface between two domains. Based on this new model, we are able to reconcile numerous results of mutagenesis and chemical cross-linking within the catalytic domains. Furthermore, we have used the model to predict the configuration of Mg·ATP at its binding site. Based on this prediction, we propose a mechanism, involving a change in Mg2+liganding, for initiating the domain movements that couple sites of ion transport to ATP hydrolysis.