Phosphorylation of the transcriptional repressor MYB15 by mitogen-activated protein kinase 6 is required for freezing tolerance in Arabidopsis.
Phosphorylation of the transcriptional repressor MYB15 by mitogen-activated protein kinase 6 is required for freezing tolerance in Arabidopsis.
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DOI：
10.1093/nar/gkx417
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发表时间：
2017-06-20
影响因子：
14.9
通讯作者：
Chung WS
中科院分区：
文献类型：
--
作者：
Kim SH;Kim HS;Bahk S;An J;Yoo Y;Kim JY;Chung WS
CBF（C-repeat-binding factor）基因的表达是拟南芥抗冻性所必需的。CBF受CBF表达诱导剂1（ICE 1）的正调控，受MYB 15的负调控。这些转录因子直接与CBF启动子中的特定元件相互作用。丝裂原活化蛋白激酶（MAPK/MPK）级联在上游起作用以调节CBF。然而，在冷应激信号传导过程中MPKs控制CBF表达的机制仍然未知。这项研究表明，MYB 15的活性，冷信号的转录抑制因子，是由MPK 6介导的磷酸化调节。MYB 15与MPK 6特异性相互作用，MPK 6使MYB 15在Ser 168上磷酸化。MPK 6诱导的磷酸化降低了MYB 15与CBF 3启动子结合的亲和力，其磷酸化位点（MYB 15 S168 A）的突变增强了MYB 15对CBF 3的转录抑制。此外，与过表达MYB 15的植物相比，过表达MYB 15 S168 A的转基因植物在响应冷胁迫时表现出显著降低的CBF转录水平。MYB 15 S168 A过表达的植物也比MYB 15过表达的植物对冷冻更敏感。这些结果表明MPK 6介导的MYB 15调控在拟南芥冷胁迫信号转导中起重要作用。
The expression of CBF (C-repeat-binding factor) genes is required for freezing tolerance in Arabidopsis thaliana. CBFs are positively regulated by INDUCER OF CBF EXPRESSION1 (ICE1) and negatively regulated by MYB15. These transcription factors directly interact with specific elements in the CBF promoters. Mitogen-activated protein kinase (MAPK/MPK) cascades function upstream to regulate CBFs. However, the mechanism by which MPKs control CBF expression during cold stress signaling remains unknown. This study showed that the activity of MYB15, a transcriptional repressor of cold signaling, is regulated by MPK6-mediated phosphorylation. MYB15 specifically interacts with MPK6, and MPK6 phosphorylates MYB15 on Ser168. MPK6-induced phosphorylation reduced the affinity of MYB15 binding to the CBF3 promoter and mutation of its phosphorylation site (MYB15S168A) enhanced the transcriptional repression of CBF3 by MYB15. Furthermore, transgenic plants overexpressing MYB15S168A showed significantly reduced CBF transcript levels in response to cold stress, compared with plants overexpressing MYB15. The MYB15S168A-overexpressing plants were also more sensitive to freezing than MYB15-overexpressing plants. These results suggest that MPK6-mediated regulation of MYB15 plays an important role in cold stress signaling in Arabidopsis.