Solution structure of the transmembrane H+-transporting subunit c of the F1F0 ATP synthase
Solution structure of the transmembrane H+-transporting subunit c of the F1F0 ATP synthase
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DOI：
10.1021/bi980511m
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发表时间：
1998-06-23
期刊：
影响因子：
2.9
通讯作者：
Fillingame, RH
中科院分区：
文献类型：
--
作者：
Girvin, ME;Rastogi, VK;Fillingame, RH
亚基c是F1 F0 ATP合酶复合物的H+转运组分。H+转运与构象变化相结合，最终导致酶合成ATP。在氯仿-甲醇-水（4：4：1）的单相溶液中的单体亚基的性质已被证明是模仿天然复合物中的蛋白质的性质。使用三重共振NMR实验来确定该溶剂混合物中单体亚基c的完整结构。蛋白质的结构由>2000质子间距离、64（3）J（N α）和43个氢键NMR衍生的限制来定义。两个跨膜螺旋的骨架原子的均方根偏差为0.63埃。蛋白质折叠为两个反平行螺旋片段的发夹，由一个短的结构环连接。保守的Arg 41-Gln 42-Pro43形成该环的顶部。必需的H+转运Asp 61残基位于C-末端螺旋中间的轻微断裂处，就在Pro64之前。C-末端螺旋在保守的Pro64处改变方向30 +/-5度。在其质子化形式中，Asp 61位于N-末端螺旋中Gly 23和Gly 27处不存在侧链所产生的空腔中。单体蛋白质分子表面的形状和电荷分布表明寡聚蛋白质在F-O复合物中的堆积排列，其中一个单体的正面有利地堆积在第二个单体的背面上。包装表明质子（阳离子）结合位点位于相邻亚基c的包装对之间。
Subunit c is the H+-translocating component of the F1F0 ATP synthase complex. H+ transport is coupled to conformational changes that ultimately lead to ATP synthesis by the enzyme. The properties of the monomeric subunit in a single phase solution of chloroform-methanol - water (4:4:1) have been shown to mimic those of the protein in the native complex. Triple resonance NMR experiments were used to determine the complete structure of monomeric subunit c in this solvent mixture. The structure of the protein was defined by >2000 interproton distances, 64 (3)J(N alpha), and 43 hydrogen-bonding NMR-derived restraints. The root mean squared deviation for the backbone atoms of the two transmembrane helices was 0.63 Angstrom. The protein folds as a hairpin of two antiparallel helical segments, connected by a short structured loop. The conserved Arg41-Gln42-Pro43 form the top of this loop. The essential H+-transporting Asp61 residue is located at a slight break in the middle of the C-terminal helix, just prior to Pro64. The C-terminal helix changes direction by 30 +/- 5 degrees at the conserved Pro64. In its protonated form, the Asp61 lies in a cavity created by the absence of side chains at Gly23 and Gly27 in the N-terminal helix. The shape and charge distribution of the molecular surface of the monomeric protein suggest a packing arrangement for the oligomeric protein in the F-o complex, with the front face of one monomer packing favorably against the back face of a second monomer. The packing suggests that the proton (cation) binding site lies between packed pairs of adjacent subunit c.