細胞分裂素參與調控植物生長發(fā)育中幾乎所有重要過程,。細胞分裂素信號轉導是通過一個連續(xù)磷酸傳遞（phosphorelay）而介導的,。在擬南芥中，被細胞分裂素激活的受體自磷酸化后,，將磷酸基團傳遞至磷酸轉移蛋白（AHP）,，并進一步傳遞至下游的反應調節(jié)子（ARR）。對細胞分裂素信號轉導中調節(jié)機制,，特別是對磷酸傳遞的調節(jié)機制了解很少,。
中國科學院遺傳與發(fā)育生物學研究所左建儒研究組與中國科學院動物研究所李曉明博士的合作研究發(fā)現一氧化氮負調控細胞分裂素信號轉導。一氧化氮的一個主要生化功能是對蛋白質特異半胱氨酸殘基的巰基進行S-亞硝基化修飾,。S-亞硝基化修飾是一種基于氧化還原的蛋白質翻譯后修飾機制,。與磷酸化等蛋白質翻譯后修飾機制類似，S-亞硝基化修飾參與調控其靶蛋白的生物學活性,。左建儒研究組發(fā)現S-亞硝基化修飾細胞分裂素信號通路的重要組分AHP1后,，抑制AHP1及其下游組分ARR1的磷酸化，從而負調控細胞分裂素信號轉導以及植物對細胞分裂素的響應,。該項研究為解析細胞分裂素信號通路感受氧化還原信號進而調控植物生長發(fā)育的機制提供了新線索。
該研究結果于2月26日在線發(fā)表于《自然—通訊》（Nature Communications）,。左建儒研究組的馮健博士為論文的第一作者,。該項研究得到了國家自然科學基金的資助。（生物谷Bioon.com）
doi:10.1038/ncomms2541
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S-nitrosylation of phosphotransfer proteins represses cytokinin signaling
Jian Feng, Chun Wang, Qingguo Chen, Hui Chen, Bo Ren, Xiaoming Li & Jianru Zuo
Cytokinin is an essential phytohormone in plant growth and development. In Arabidopsis, cytokinin signalling is mediated by a phosphorelay that sequentially transfers phosphoryl groups from the cytokinin receptors to histidine phosphotransfer proteins (AHPs) and response regulators (ARRs). However, little is known about the regulatory mechanism of the phosphorelay. Here, we show that nitric oxide negatively regulates cytokinin signalling by inhibiting the phosphorelay activity through S-nitrosylation. S-nitrosylation of AHP1 at Cys 115 represses its phosphorylation and subsequent transfer of the phosphoryl group to ARR1. A non-nitrosylatable mutation of AHP1 renders the mutant protein insensitive to nitric oxide in repressing its phosphorylation, and partially relieves the inhibitory effect of nitric oxide on the cytokinin response. Conversely, a nitrosomimetic mutation of AHP1 causes reduced phosphorylation of AHP1 and ARR1, thereby resulting in a compromised cytokinin response. These findings illustrate a mechanism by which redox signalling and cytokinin signalling coordinate plant growth and development.
