Stimulation of cation transport in mitochondria by gramicidin and truncated derivatives.
Stimulation of cation transport in mitochondria by gramicidin and truncated derivatives.
复制标题
短杆菌肽和截短衍生物刺激线粒体中的阳离子转运。
DOI：
10.1021/bi00436a036
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Koeppe2nd,RE
中科院分区：
文献类型：
--
作者：
Rottenberg,H;Koeppe2nd,RE
宾夕法尼亚州费城哈内曼大学病理学系，19102;阿肯色州费耶特维尔大学化学和生物化学系，阿肯色州72701，1988年11月7日接收;修订后的手稿，1989年2月3日接收摘要：短杆菌肽及其截短衍生物去甲酰基短杆菌肽（desfor）和des（甲酰-缬氨酰）短杆菌肽（desval）刺激大鼠肝线粒体单价阳离子转运。阳离子通量进行了比较，间接从膜电位在稳态（状态4）的阳离子的效果，或从相关的刺激电子传递。Rb+转运直接从86 Rb的摄取测量。与短杆菌肽相比，截短杆菌肽显示出对K+和Rb+的增强的选择性。此外，碱性阳离子系列内的选择性模式发生改变，即，与短杆菌肽的Cs+> Rb+> K+=Na+> Li+相比，Rb+> K+> Cs+> Na+> Li+对于desfor和desval。通过截断衍生物的阳离子通量更强烈地依赖于阳离子浓度。高浓度的渗透阳离子的存在下，增强了其他阳离子的运输通过截断的衍生物通道，这表明阳离子是需要稳定的通道结构。在高浓度的KCl中，desfor和desval在降低线粒体膜电位方面几乎与短杆菌肽一样有效，因此，在氧化磷酸化的解偶联和ATP水解的增强方面也是如此。脂质体的初步实验表明，86 Rb交换被desforand desval刺激的程度几乎与短杆菌肽相同。这些结果表明短杆菌肽截短体形成了一种新型的导电通道，其电导特性和结构与短杆菌肽头对头的单链j86 ′ 3-螺旋二聚体（“通道”）不同。截断衍生物的二级结构的基础上，我们建议，反平行双链螺旋二聚体（“孔”）是一个可能的替代结构，这种新的通道。
Department of Pathology, Hahnemann University, Philadelphia, Pennsylvania 19102, and Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701 Received November 7, 1988; Revised Manuscript Received February 3, 1989 abstract: Gramicidin and the truncated derivatives desformylgramicidin (desfor) and des (formyl-valyl) gramicidin (desval) stimulate monovalent cation transport in rat liver mitochondria. Cation fluxes were compared indirectly from the effect of cations on the membrane potential at steady state (state 4) or from the associated stimulation of electron transport. Rb+ transport was measured directly from the uptake of 86Rb. The truncated gramicidins show enhanced selectivity for K+ and Rb+ when compared to gramicidin. Moreover, the pattern of selectivity within the alkali cation series is altered, ie, Rb+> K+> Cs+> Na+> Li+ for desfor and desval as compared to Cs+> Rb+> K+=Na+> Li+ for gramicidin. The cation fluxes through the truncated derivatives are more strongly dependent on the cation concentration. The presence of high concentrations of permeating cation enhances the transport of other cations through the truncated derivative channels, suggesting that cations are required for stabilizing the channel structure. In high concentrations of KC1, desfor and desval are nearly as effective as gramicidin in collapsingthe mitochondrial membrane potential, and, consequently, in the uncoupling of oxidative phosphorylation and enhancement of ATP hydrolysis. Preliminary experiments with liposomes show that 86Rb exchange is stimulated by desforand desval almost to the same extent as gramicidin. These results strongly suggest that the truncated gramicidinsform a novel conducting channel whichdiffers from the gramicidin headto-head, single-stranded j86'3-helical dimer (“channel”) inits conductance characteristic and its structure. On the basis of the secondary structure of the truncated derivatives, we suggest that the antiparallel double-stranded helix dimer (“pore”) is a likely alternative structure for this novel channel.