Two-component circuitry in Arabidopsis cytokinin signal transduction
Two-component circuitry in Arabidopsis cytokinin signal transduction
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DOI：
10.1038/35096500
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发表时间：
2001-09-27
期刊：
影响因子：
64.8
通讯作者：
Sheen, J
中科院分区：
文献类型：
--
作者：
Hwang, I;Sheen, J
细胞分裂素是植物生长发育过程中必需的激素，参与茎分生组织和叶片的形成、细胞分裂、叶绿体的发生和衰老。虽然杂合组氨酸蛋白激酶已被牵连在拟南芥细胞分裂素的感知，组氨酸蛋白激酶受体和下游信号通路的行动至今尚未阐明。在这里，我们确定了一个真核双组分信号电路，启动细胞分裂素信号通过不同的混合组氨酸蛋白激酶在质膜的活动。组氨酸磷酸递质以细胞分裂素依赖的方式作为细胞质和细胞核之间的信号穿梭机。短信号通路通过使核反应调节因子ARR1、ARR2和ARR10作为转录激活因子而到达核靶基因。细胞分裂素诱导的ARR4、ARR5、ARR6和ARR7基因编码转录阻遏物，其介导细胞分裂素信号传导中的负反馈环。ARR2是细胞分裂素反应的限速因子，在转基因拟南芥中的异位表达足以模拟细胞分裂素促进茎分生组织增殖和叶片分化，并延缓叶片衰老。
Cytokinins are essential plant hormones that are involved in shoot meristem and leaf formation, cell division, chloroplast biogenesis and senescence. Although hybrid histidine protein kinases have been implicated in cytokinin perception in Arabidopsis, the action of histidine protein kinase receptors and the downstream signalling pathway has not been elucidated to date. Here we identify a eukaryotic two-component signalling circuit that initiates cytokinin signalling through distinct hybrid histidine protein kinase activities at the plasma membrane. Histidine phosphotransmitters act as signalling shuttles between the cytoplasm and nucleus in a cytokinin-dependent manner. The short signalling circuit reaches the nuclear target genes by enabling nuclear response regulators ARR1, ARR2 and ARR10 as transcription activators. The cytokinin-inducible ARR4, ARR5, ARR6 and ARR7 genes encode transcription repressors that mediate a negative feedback loop in cytokinin signalling. Ectopic expression in transgenic Arabidopsis of ARR2, the rate-limiting factor in the response to cytokinin, is sufficient to mimic cytokinin in promoting shoot meristem proliferation and leaf differentiation, and in delaying leaf senescence.