An electrostatic switch controls palmitoylation of the large conductance voltage- and calcium-activated potassium (BK) channel.
An electrostatic switch controls palmitoylation of the large conductance voltage- and calcium-activated potassium (BK) channel.
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DOI：
10.1074/jbc.m111.224840
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发表时间：
2012-01-06
期刊：
影响因子：
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通讯作者：
Shipston MJ
中科院分区：
文献类型：
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作者：
Jeffries O;Tian L;McClafferty H;Shipston MJ
背景：棕榈酰化作用控制离子通道的性质和功能，但控制棕榈酰化作用的机制还不清楚。结果：棕榈酰化半胱氨酸上游多碱结构域的磷酸化控制着BK通道的棕榈酰化和性质。结论：多碱基结构域是控制棕榈酰化的静电开关。意义：了解棕榈酰化是如何调节的，对于理解这一信号机制在健康和疾病中的生理作用至关重要。蛋白质棕榈酰化是蛋白质功能的主要动态翻译后调节因子。然而，控制棕榈酰化的机制却知之甚少。在许多蛋白质中，棕榈酰化发生在半胱氨酸残基与膜锚定结构域并列的位置，如跨膜螺旋、不可逆脂类修饰部位、疏水和/或多碱性结构域。特别是，多碱结构域是一种很有吸引力的动态控制蛋白质棕榈酰化的机制，因为这些结构域的功能会受到蛋白质磷酸化的显著影响。在这里，我们证明了在大电导钙和电压激活的钾通道的C末端，棕榈酰化半胱氨酸残基上游的一个多碱结构域是通道棕榈酰化和功能的重要决定因素。碱性氨基酸突变为多碱结构域中的酸性残基，导致通道棕榈酰化受到抑制，通道最大激活电压显著右移。重要的是，蛋白激酶A依赖于多碱基结构域核心内单个丝氨酸残基的磷酸化，从而导致通道抑制，也减少了通道棕榈酸化。这些数据证明了多碱结构域在控制应力调节的外显子棕榈酰化中的关键作用，并表明磷酸化通过充当静电开关来控制该结构域。
Background: Palmitoylation controls ion channel properties and function, but mechanisms that control palmitoylation are poorly defined. Results: Phosphorylation of a polybasic domain upstream of palmitoylated cysteines controls BK channel palmitoylation and properties. Conclusion: The polybasic domain is an electrostatic switch controlling palmitoylation. Significance: Knowledge of how palmitoylation is regulated is essential for understanding the physiological role of this signaling mechanism in health and disease. Protein palmitoylation is a major dynamic posttranslational regulator of protein function. However, mechanisms that control palmitoylation are poorly understood. In many proteins, palmitoylation occurs at cysteine residues juxtaposed to membrane-anchoring domains such as transmembrane helices, sites of irreversible lipid modification, or hydrophobic and/or polybasic domains. In particular, polybasic domains represent an attractive mechanism to dynamically control protein palmitoylation, as the function of these domains can be dramatically influenced by protein phosphorylation. Here we demonstrate that a polybasic domain immediately upstream of palmitoylated cysteine residues within an alternatively spliced insert in the C terminus of the large conductance calcium- and voltage-activated potassium channel is an important determinant of channel palmitoylation and function. Mutation of basic amino acids to acidic residues within the polybasic domain results in inhibition of channel palmitoylation and a significant right-shift in channel half maximal voltage for activation. Importantly, protein kinase A-dependent phosphorylation of a single serine residue within the core of the polybasic domain, which results in channel inhibition, also reduces channel palmitoylation. These data demonstrate the key role of the polybasic domain in controlling stress-regulated exon palmitoylation and suggests that phosphorylation controls the domain by acting as an electrostatic switch.