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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Structure of the subunit c oligomer in the F_1F_0 ATP synthase: Model derived from solution structure of the monomer and cross-linking in the native enzyme
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Structure of the subunit c oligomer in the F_1F_0 ATP synthase: Model derived from solution structure of the monomer and cross-linking in the native enzyme

机译：F_1F_0 ATP合酶中c亚基低聚物的结构：模型源自单体的溶液结构和天然酶中的交联

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摘要

The structure of the subunit c oligomer of the H~+-transporting ATP synthase of Escherichia coli has been modeled by molecular dynamics and energy minimization calculations from the solution structure of monomeric subunit c and 21 intersubunit distance constraints derived from cross-linking of subunits. Subunit c folds in a hairpin-like structure with two transmembrane helices. In the C12 oligomer model, the subunits pack to form a compact hollow cylinder with an outer diameter of 55-60 A and an inner space with a minimal diameter of 11-12 A. Phospholipids are presumed to pack in the inner space in the native membrane. The transmembrane helices pack in two concentric rings with helix 1 inside and helix 2 outside. The calculations strongly favor this structure versus a model with helix 2 inside and helix 1 outside. Asp-61, the H~+-transporting residue, packs toward the center of the four transmembrane helices of two interacting subunits. From this position at the front face of one subunit, the Asp-61 carboxylate lies proximal to side chains of Ala-24, Ile-28, and Ala-62, projecting from the back face of a second subunit. These interactions were predicted from previous mutational analyses. The packing supports the suggestion that a c-c dimer is the functional unit. The positioning of the Asp-61 carboxyl in the center of the interacting transmembrane helices, rather than at the periphery of the cylinder, has important implications regarding possible mechanisms of H~+-transport-driven rotation of the c oligomer during ATP synthesis.
机译：大肠杆菌的H +转运ATP合酶的亚基c低聚物的结构已通过分子动力学和能量最小化计算，由单体亚基c的溶液结构和源自亚基交联的21个亚基间距离限制进行了建模。 c亚基以两个跨膜螺旋的发夹状结构折叠。在C12低聚物模型中，这些亚基堆积形成一个紧凑的空心圆柱体，其外径为55-60 A，内部空间的最小直径为11-12A。在天然物质的内部空间中，磷脂被认为堆积膜。跨膜螺旋包裹在两个同心环中，里面有1个螺旋，外面是2个螺旋。与内部带有螺旋线2和外部带有螺旋线1的模型相比，此计算强烈支持这种结构。 H +转运残基Asp-61朝向两个相互作用亚基的四个跨膜螺旋的中心堆积。从一个亚基的前面的位置开始，Asp-61羧酸盐位于第二个亚基的背面，靠近Ala-24，Ile-28和Ala-62的侧链。这些相互作用是根据以前的突变分析预测的。包装支持c-c二聚体是功能单元的建议。 Asp-61羧基在相互作用的跨膜螺旋的中心，而不是在圆柱体的外围，对ATP合成过程中低聚物的H +转运驱动旋转的可能机理具有重要意义。

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