Structure of the subunit c oligomer in the F1F0 ATP synthase:: Model derived from solution structure of the monomer and cross-linking in the native enzyme
Structure of the subunit c oligomer in the F1F0 ATP synthase:: Model derived from solution structure of the monomer and cross-linking in the native enzyme
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DOI：
10.1073/pnas.96.14.7785
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发表时间：
1999-07-06
影响因子：
11.1
通讯作者：
Fillingame, RH
中科院分区：
文献类型：
--
作者：
Dmitriev, OY;Jones, PC;Fillingame, RH
利用分子动力学和能量最小化方法对大肠杆菌H+转运三磷酸腺苷合成酶c亚基的结构进行了模拟，根据单体c亚基的溶液结构和21个亚基之间的距离约束，c亚基折叠成具有两个跨膜螺旋的发夹状结构，在c(12)寡聚体模型中，亚基包装成一个外径55-60埃、内径最小11-12埃的致密中空圆柱体。磷脂被认为堆积在天然膜的内部空间。跨膜螺旋包装在两个同心环中，螺旋1在内，螺旋2在外，计算结果强烈支持这种结构，而不是内有螺旋2，外有螺旋1的模型。Asp-61是H+转运残基，向两个相互作用的亚基的四个跨膜螺旋的中心包装，从一个亚基正面的这个位置，Asp-61羧酸位于Ala-24、Ile-28和Ala-62侧链的近端，从第二个亚基的背面伸出。这些相互作用是从先前的突变分析中预测出来的。包装支持c-c二聚体是功能单元的说法。Asp-61羧基位于相互作用的跨膜螺旋的中心，而不是圆柱体的外围，这对ATP合成过程中H+转运驱动c寡聚体旋转的可能机制具有重要意义。
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 c(12) oligomer model, the subunits pack to form a compact hollow cylinder with an outer diameter of 55-60 Angstrom and an inner space with a minimal diameter of 11-12 Angstrom. 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.