Palmitoylation of the Cysteine Residue in the DHHC Motif of a Palmitoyl Transferase Mediates Ca2+ Homeostasis in Aspergillus.
Palmitoylation of the Cysteine Residue in the DHHC Motif of a Palmitoyl Transferase Mediates Ca2+ Homeostasis in Aspergillus.
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棕榈酰转移酶 DHHC 基序中半胱氨酸残基的棕榈酰化介导曲霉中的 Ca2 稳态
DOI：
10.1371/journal.pgen.1005977
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发表时间：
2016-04
期刊：
影响因子：
4.5
通讯作者：
Lu L
中科院分区：
文献类型：
--
作者：
Zhang Y;Zheng Q;Sun C;Song J;Gao L;Zhang S;Muñoz A;Read ND;Lu L
胞质游离钙（[Ca2+]c）的精细调节变化介导了许多细胞内功能，导致一系列靶蛋白的激活或失活。棕榈酰化是一种可逆的翻译后修饰，涉及膜蛋白在膜之间的运输及其功能调节。然而，关于棕榈酰化与钙信号传导之间关系的研究还很有限。在这里，我们证明了酵母棕榈酰转移酶ScAkr1p同源物，即细粒曲霉中的AkrA，调节[Ca2+]c稳态。在低钙条件下，akrA的缺失对菌丝生长和分生有明显的影响，这与删除高亲和钙吸收系统（HACS）成分的影响相似。在不同akrA突变背景下，表达钙报告蛋白aequorin的活细胞中的[Ca2+]c动力学在对高细胞外Ca2+应激或引起内质膜或质膜应激的药物的[Ca2+]c反应中存在缺陷。所有这些对AkrA介导的[Ca2+]c反应的影响都与AkrA DHHC基元的半胱氨酸残基密切相关，这是AkrA棕榈酰化所必需的。利用酰基生物素交换化学分析结合蛋白质组学质谱法，我们鉴定出了AkrA棕榈酰化的蛋白底物，包括两个新的推测的p型atp酶（Pmc1和Spf1同源物），一个推测的质子v型atp酶（Vma5同源物）和三个推测的a . nidulans蛋白，这些蛋白的转录本先前被证明是由细胞外钙胁迫以依赖crza的方式诱导的。因此，我们的研究结果提供了强有力的证据，证明AkrA蛋白通过棕榈酰化这些候选蛋白来调节[Ca2+]c稳态，并为棕榈酰化在调节钙介导的细胞外、内质网或质膜应激反应中的作用提供了新的见解。
Finely tuned changes in cytosolic free calcium ([Ca2+]c) mediate numerous intracellular functions resulting in the activation or inactivation of a series of target proteins. Palmitoylation is a reversible post-translational modification involved in membrane protein trafficking between membranes and in their functional modulation. However, studies on the relationship between palmitoylation and calcium signaling have been limited. Here, we demonstrate that the yeast palmitoyl transferase ScAkr1p homolog, AkrA in Aspergillus nidulans, regulates [Ca2+]c homeostasis. Deletion of akrA showed marked defects in hyphal growth and conidiation under low calcium conditions which were similar to the effects of deleting components of the high-affinity calcium uptake system (HACS). The [Ca2+]c dynamics in living cells expressing the calcium reporter aequorin in different akrA mutant backgrounds were defective in their [Ca2+]c responses to high extracellular Ca2+ stress or drugs that cause ER or plasma membrane stress. All of these effects on the [Ca2+]c responses mediated by AkrA were closely associated with the cysteine residue of the AkrA DHHC motif, which is required for palmitoylation by AkrA. Using the acyl-biotin exchange chemistry assay combined with proteomic mass spectrometry, we identified protein substrates palmitoylated by AkrA including two new putative P-type ATPases (Pmc1 and Spf1 homologs), a putative proton V-type proton ATPase (Vma5 homolog) and three putative proteins in A. nidulans, the transcripts of which have previously been shown to be induced by extracellular calcium stress in a CrzA-dependent manner. Thus, our findings provide strong evidence that the AkrA protein regulates [Ca2+]c homeostasis by palmitoylating these protein candidates and give new insights the role of palmitoylation in the regulation of calcium-mediated responses to extracellular, ER or plasma membrane stress.