Chlorella virus ATCV-1 encodes a functional potassium channel of 82 amino acids.
Chlorella virus ATCV-1 encodes a functional potassium channel of 82 amino acids.
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DOI：
10.1042/bj20090095
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发表时间：
2009-05-13
期刊：
影响因子：
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通讯作者：
Moroni A
中科院分区：
文献类型：
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作者：
Gazzarrini S;Kang M;Abenavoli A;Romani G;Olivari C;Gaslini D;Ferrara G;van Etten JL;Kreim M;Kast SM;Thiel G;Moroni A
小球藻病毒PBCV-1（Paramecium bursaria pancreella virus-1）编码最小的蛋白质（94个氨基酸，命名为Kcv），先前已知在异源系统中形成功能性K+通道。在本文中，我们描述了另一种隐球菌病毒编码的K+通道蛋白（82个氨基酸，命名为ATCV-1 KCV），它在非洲爪蟾卵母细胞中形成了一个功能通道，并拯救了缺乏内源性K+摄取系统的酿酒酵母突变体。与较大的PBCV-1 Kcv相比，ATCV-1 Kcv缺乏胞质N-末端，并且在其转塔结构域中具有减少的带电氨基酸数量。尽管存在这些缺陷，ATCV-1 Kcv实现了K+通道的所有主要特征：它组装成四聚体，具有K+选择性，并被典型的K+通道阻断剂钡和铯抑制。单通道分析揭示了随机门控行为和电压依赖性电导，类似于宏观I/V关系。PBCV-1和ATCV-1 Kcv之间的一个差异是，后者比Rb+更易渗透K+。这种差异部分是由于ATCV-1 Kcv的选择性过滤器中存在酪氨酸残基，而PBCV-1 Kcv具有苯丙氨酸。因此，ATCV-1 Kcv是形成K+通道的最小蛋白质，它将作为研究钾通道孔内结构-功能相关性的模型。
Chlorella virus PBCV-1 (Paramecium bursaria chlorella virus-1) encodes the smallest protein (94 amino acids, named Kcv) previously known to form a functional K+ channel in heterologous systems. In this paper, we characterize another chlorella virus encoded K+ channel protein (82 amino acids, named ATCV-1 Kcv) that forms a functional channel in Xenopus oocytes and rescues Saccharomyces cerevisiae mutants that lack endogenous K+ uptake systems. Compared with the larger PBCV-1 Kcv, ATCV-1 Kcv lacks a cytoplasmic N-terminus and has a reduced number of charged amino acids in its turret domain. Despite these deficiencies, ATCV-1 Kcv accomplishes all the major features of K+ channels: it assembles into a tetramer, is K+ selective and is inhibited by the canonical K+ channel blockers, barium and caesium. Single channel analyses reveal a stochastic gating behavior and a voltage-dependent conductance that resembles the macroscopic I/V relationship. One difference between PBCV-1 and ATCV-1 Kcv is that the latter is more permeable to K+ than Rb+. This difference is partially explained by the presence of a tyrosine residue in the selective filter of ATCV-1 Kcv, whereas PBCV-1 Kcv has a phenylalanine. Hence, ATCV-1 Kcv is the smallest protein to form a K+ channel and it will serve as a model for studying structure–function correlations inside the potassium channel pore.