Identification of amino acid substitutions that render the Arabidopsis cytokinin receptor histidine kinase AHK4 constitutively active
Identification of amino acid substitutions that render the Arabidopsis cytokinin receptor histidine kinase AHK4 constitutively active
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DOI：
10.1093/pcp/pcm145
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发表时间：
2007-12-01
影响因子：
4.9
通讯作者：
Mizuno, Takeshi
中科院分区：
文献类型：
--
作者：
Miwa, Kumiko;Ishikawa, Kuniko;Mizuno, Takeshi
在拟南芥中，有三个基因(AHK2、AHK3和AHK4/CRE1)编码作为细胞分裂素受体的组氨酸激酶(His-Kinase)。为了了解外部细胞分裂素信号如何激活跨细胞膜的His-Kinase，我们利用微生物遗传学的力量分离了几个在原核和真核检测系统中独立于细胞分裂素发挥作用的AHK4突变体。在每个突变体中，在第二跨膜片段内或在磷酸化His位点周围的区域内的单个氨基酸替换使His-Kinase具有结构性活性。即使在没有刺激的情况下，这些突变的受体似乎也有一种“锁定”的构象。我们讨论了这些数据对植物中细胞分裂素受体组氨酸激动酶的结构和功能的影响。
In Arabidopsis, three genes (AHK2, AHK3 and AHK4/ CRE1) encode histidine kinases (His-kinases), which serve as cytokinin receptors. To understand how the external cytokinin signal activates the His-kinase across the cell membrane, we exploited the power of microbial genetics to isolate several AHK4 mutants that function independently of cytokinin in both prokaryotic and eukaryotic assay systems. In each mutant, a single amino acid substitution within the second membrane-spanning segment, or within the region around the phosphorylation His site, renders the His-kinase constitutively active. These mutant receptors appear to have a 'locked-on' conformation, even in the absence of stimulus. We discuss the implications of these data for the structure and function of the cytokinin receptor His-kinases in plants.