Role of tryptophan residues in gramicidin channel organization and function
Role of tryptophan residues in gramicidin channel organization and function
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DOI：
10.1529/biophysj.107.124206
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发表时间：
2008-07-01
影响因子：
3.4
通讯作者：
Koeppe, Roger E., II
中科院分区：
文献类型：
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作者：
Chattopadhyay, Amitabha;Rawat, Satinder S.;Koeppe, Roger E., II
线性肽短杆菌肽形成对单价阳离子特异的原型离子通道，并且已被广泛用于研究跨膜通道的组织、动力学和功能。短杆菌肽通道中的色氨酸残基对于维持通道的结构和功能至关重要。我们使用荧光方法的组合，其中包括红边激发位移和膜穿透深度分析，尺寸排阻色谱法和圆二色性光谱法，探索了在短杆菌肽的单色氨酸类似物的情况下，具有三个Trp ->疏水取代的通道电导降低的结构基础。我们在这里表明，含有单一色氨酸残基的短杆菌肽类似物采用混合物的非通道和通道构象，从膜渗透深度，尺寸排阻色谱分析，和骨干圆二色性数据，这是显而易见的。这些结果在分析色氨酸取代对其他离子通道和膜蛋白功能的影响方面具有潜在的应用价值。
The linear peptide gramicidin forms prototypical ion channels specific for monovalent cations and has been used extensively to study the organization, dynamics, and function of membrane-spanning channels. The tryptophan residues in gramicidin channels are crucial for maintaining the structure and function of the channel. We explored the structural basis for the reduction in channel conductance in the case of single-tryptophan analogs of gramicidin with three Trp -> hydrophobic substitutions using a combination of fluorescence approaches, which include red edge excitation shift and membrane penetration depth analysis, size-exclusion chromatography, and circular dichroism spectroscopy. We show here that the gramicidin analogs containing single-tryptophan residues adopt a mixture of nonchannel and channel conformations, as evident from analysis of membrane penetration depth, size-exclusion chromatography, and backbone circular dichroism data. These results are potentially useful in analyzing the effect of tryptophan substitution on the functioning of other ion channels and membrane proteins.