Abscisic acid-dependent multisite phosphorylation regulates the activity of a transcription activator AREB1
Abscisic acid-dependent multisite phosphorylation regulates the activity of a transcription activator AREB1
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DOI：
10.1073/pnas.0505667103
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发表时间：
2006-02-07
影响因子：
11.1
通讯作者：
Yamaguchi-Shinozaki, K
中科院分区：
文献类型：
--
作者：
Furihata, T;Maruyama, K;Yamaguchi-Shinozaki, K
bZIP型转录因子AREBs/ABFs结合一个ABA应答顺式作用元件ABRE，并反式激活拟南芥下游基因的表达。由于AREB 1过表达不能诱导下游基因表达，因此AREB 1的激活需要ABA依赖的转录后修饰。我们证实，阿坝激活42-kDa激酶活性，这反过来，磷酸化丝氨酸/苏氨酸残基的R-X-X-S/T位点的保守区域的AREB 1。氨基酸取代的R-X-X-S/T位点的Ala抑制的反式激活活性，和这些网站的多个取代导致几乎完全抑制的反式激活活性在瞬时测定。与此相反，取代的Ser/Thr残基的天冬氨酸导致高的反式激活活性没有外源阿坝的应用。通过将所有保守的R-X-X-S/T位点中的Ser/Thr替换为Asp，获得磷酸化的转录活性形式。过表达AREB 1磷酸化活性形式的转基因植物在没有阿坝处理的情况下表达了许多ABA诱导的基因，例如RD 29 B。这些结果表明，ABA依赖的多位点磷酸化的AREB 1调节其自身的激活在植物中。
bZIP-type transcription factors AREBs/ABFs bind an abscisic acid (ABA)-responsive cis-acting element named ABRE and transactivate downstream gene expression in Arabidopsis. Because AREB1 overexpression could not induce downstream gene expression, activation of AREB1 requires ABA-dependent posttranscriptional modification. We confirmed that ABA activated 42-kDa kinase activity, which, in turn, phosphorylated Ser/Thr residues of R-X-X-S/T sites in the conserved regions of AREB1. Amino acid substitutions of R-X-X-S/T sites to Ala suppressed transactivation activity, and multiple substitution of these sites resulted in almost complete suppression of transactivation activity in transient assays. In contrast, substitution of the Ser/Thr residues to Asp resulted in high transactivation activity without exogenous ABA application. A phosphorylated, transcriptionally active form was achieved by substitution of Ser/Thr in all conserved R-X-X-S/T sites to Asp. Transgenic plants overexpressing the phosphorylated active form of AREB1 expressed many ABA-inducible genes, such as RD29B, without ABA treatment. These results indicate that the ABA-dependent multisite phosphorylation of AREB1 regulates its own activation in plants.