Salicylic acid signaling controls the maturation and localization of the arabidopsis defense protein ACCELERATED CELL DEATH6.
Salicylic acid signaling controls the maturation and localization of the arabidopsis defense protein ACCELERATED CELL DEATH6.
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DOI：
10.1093/mp/ssu072
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发表时间：
2014-08
期刊：
影响因子：
27.5
通讯作者：
Zhongqi Zhang;J. Shrestha;C. Tateda;J. Greenberg
中科院分区：
文献类型：
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作者：
Zhongqi Zhang;J. Shrestha;C. Tateda;J. Greenberg
加速细胞死亡6（ACD 6）是一种多通道膜蛋白，具有锚蛋白结构域，其与防御信号水杨酸（SA）在正反馈环中起作用。本研究采用生物化学方法来推断ACD 6复合物和定位的变化。除了形成内质网（ER）和质膜（PM）定位的复合物外，ACD 6还形成可溶性复合物，在那里它与细胞溶质HSP 70结合，泛素化，并通过蛋白酶体降解。因此，ACD 6组成性地经历ER相关的降解。在SA信号传导期间，可溶性ACD 6池减少，而PM池增加。类似地，ACD 6 -1（诱导SA的ACD 6的活化形式）以低水平存在于可溶性级分中，而以高水平存在于PM中。然而，在锚蛋白结构域中具有氨基酸取代的ACD 6变体形成异常的、无活性的复合物，由SA激动剂诱导，但不显示PM定位。SA信号还增加鞭毛蛋白传感2（FLS 2）和BRI 1相关受体激酶1（BAK 1）的PM池。FLS 2形成复合物ACD 6; FLS 2和BAK 1都需要ACD 6以响应SA信号在PM处最大积累。一种可能的情况是，SA增加了ER中生产性折叠和/或复合物形成的效率，使得ACD 6与FLS 2和BAK 1一起到达细胞表面以更有效地促进免疫应答。
ACCELERATED CELL DEATH6 (ACD6) is a multipass membrane protein with an ankyrin domain that acts in a positive feedback loop with the defense signal salicylic acid (SA). This study implemented biochemical approaches to infer changes in ACD6 complexes and localization. In addition to forming endoplasmic reticulum (ER)- and plasma membrane (PM)-localized complexes, ACD6 forms soluble complexes, where it is bound to cytosolic HSP70, ubiquitinated, and degraded via the proteasome. Thus, ACD6 constitutively undergoes ER-associated degradation. During SA signaling, the soluble ACD6 pool decreases, whereas the PM pool increases. Similarly, ACD6-1, an activated version of ACD6 that induces SA, is present at low levels in the soluble fraction and high levels in the PM. However, ACD6 variants with amino acid substitutions in the ankyrin domain form aberrant, inactive complexes, are induced by a SA agonist, but show no PM localization. SA signaling also increases the PM pools of FLAGELLIN SENSING2 (FLS2) and BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1). FLS2 forms complexes ACD6; both FLS2 and BAK1 require ACD6 for maximal accumulation at the PM in response to SA signaling. A plausible scenario is that SA increases the efficiency of productive folding and/or complex formation in the ER, such that ACD6, together with FLS2 and BAK1, reaches the cell surface to more effectively promote immune responses.