Two N-Terminal Acetyltransferases Antagonistically Regulate the Stability of a Nod-Like Receptor in Arabidopsis
Two N-Terminal Acetyltransferases Antagonistically Regulate the Stability of a Nod-Like Receptor in Arabidopsis
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DOI：
10.1105/tpc.15.00173
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发表时间：
2015-05-01
期刊：
影响因子：
11.6
通讯作者：
Li, Xin
中科院分区：
文献类型：
--
作者：
Xu, Fang;Huang, Yan;Li, Xin
nod样受体（NLRs）是植物和动物的免疫受体。nlr的稳定性受到严格监管，尽管其机制尚不清楚。在这里，我们展示了n端乙酰化对拟南芥NPR1抑制因子组成1 （SNC1）的转换的关键影响。SNC1的遗传和生化分析揭示了其受不同n端乙酰转移酶（Nat）复合物的多层调控。SNC1表现出几个不同的n端异构体，通过交替起始和n端乙酰化产生。第一个Met被n端乙酰转移酶复合物A （NatA）乙酰化，第二个Met被n端乙酰转移酶复合物B （NatB）乙酰化。出乎意料的是，nata介导的乙酰化是一个降解信号，而natb介导的乙酰化稳定了NLR蛋白，从而揭示了单个蛋白底物的拮抗n端乙酰化。此外，NatA还有助于另一种NLR的转化，即抗紫丁香P. pv maculicola 1。据推测，Nats对蛋白质稳定性的复杂调控为目标蛋白维持其稳态提供了灵活性。
Nod-like receptors (NLRs) serve as immune receptors in plants and animals. The stability of NLRs is tightly regulated, though its mechanism is not well understood. Here, we show the crucial impact of N-terminal acetylation on the turnover of one plant NLR, Suppressor of NPR1, Constitutive 1 (SNC1), in Arabidopsis thaliana. Genetic and biochemical analyses of SNC1 uncovered its multilayered regulation by different N-terminal acetyltransferase (Nat) complexes. SNC1 exhibits a few distinct N-terminal isoforms generated through alternative initiation and N-terminal acetylation. Its first Met is acetylated by N-terminal acetyltransferase complex A (NatA), while the second Met is acetylated by N-terminal acetyltransferase complex B (NatB). Unexpectedly, the NatA-mediated acetylation serves as a degradation signal, while NatB-mediated acetylation stabilizes the NLR protein, thus revealing antagonistic N-terminal acetylation of a single protein substrate. Moreover, NatA also contributes to the turnover of another NLR, RESISTANCE TO P. syringae pv maculicola 1. The intricate regulation of protein stability by Nats is speculated to provide flexibility for the target protein in maintaining its homeostasis.