Interactions between beta D372 and gamma subunit N-terminus residues gamma K9 and gamma S12 are important to catalytic activity catalyzed by Escherichia coli F1F0-ATP synthase.
Interactions between beta D372 and gamma subunit N-terminus residues gamma K9 and gamma S12 are important to catalytic activity catalyzed by Escherichia coli F1F0-ATP synthase.
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β D372 和 γ 亚基 N 末端残基 γ K9 和 γ S12 之间的相互作用对于大肠杆菌 F1F0-ATP 合酶的催化活性很重要。
DOI：
10.1021/bi047293j
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Frasch,WayneD
中科院分区：
文献类型：
--
作者：
Lowry,DavidS;Frasch,WayneD
用不能形成氢键的基团取代EscherichiacoliF1FoATP合酶的β D372或γ S12残基，使ATP酶依赖的细胞生长降低2个数量级，消除了F1Fo催化ATP酶依赖的质子泵的能力。coolimembranes，导致15 - 20%的耦合效率的膜，如琥珀酸依赖性吖啶橙子荧光淬灭的程度测量，但增加了约10%的可溶性F1-ATP酶活性。用γ K9取代β D372以消除形成盐桥的能力，使可溶性F1-ATPase活性和ATPase驱动的质子泵降低2倍，但对加入琥珀酸诱导的质子梯度没有影响。消除γ亚基N-末端上的其他不太高度保守的残基与β亚基之间形成亚基间氢键和盐桥的可能性的突变对ATP酶或ATP合酶活性几乎没有影响。这些结果表明，β D372 − γ K9盐桥对ATP水解可溶性F1的限速步骤有重要贡献，而β D372 − γ S12氢键可能是ATP合成的逃逸机制的一个组成部分，其中α β γ亚基间相互作用提供了一种手段，使底物结合成为质子梯度驱动的γ亚基旋转的先决条件。
Substitution ofEscherichia coliF1FoATP synthase residues βD372 or γS12 with groups that are unable to form a hydrogen bond at this location decreased ATP synthase-dependent cell growth by 2 orders of magnitude, eliminated the ability of F1Foto catalyze ATPase-dependent proton pumping in invertedE. colimembranes, caused a 15−20% decrease in the coupling efficiency of the membranes as measured by the extent of succinate-dependent acridine orange fluorescence quenching, but increased soluble F1-ATPase activity by about 10%. Substitution of γK9 to eliminate the ability to form a salt bridge with βD372 decreased soluble F1-ATPase activity and ATPase-driven proton pumping by 2-fold but had no effect on the proton gradient induced by addition of succinate. Mutations to eliminate the potential to form intersubunit hydrogen bonds and salt bridges between other less highly conserved residues on the γ subunit N-terminus and the β subunits had little effect on ATPase or ATP synthase activities. These results suggest that the βD372−γK9 salt bridge contributes significantly to the rate-limiting step in ATP hydrolysis of soluble F1while the βD372−γS12 hydrogen bond may serve as a component of an escapement mechanism for ATP synthesis in which αβγ intersubunit interactions provide a means to make substrate binding a prerequisite of proton gradient-driven γ subunit rotation.