The unphosphorylated receiver domain of PhoB silences the activity of its output domain
The unphosphorylated receiver domain of PhoB silences the activity of its output domain
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DOI：
10.1128/jb.182.23.6592-6597.2000
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发表时间：
2000-12-01
影响因子：
3.2
通讯作者：
McCleary, WR
中科院分区：
文献类型：
--
作者：
Ellison, DW;McCleary, WR
PhoB是Pho调节子的反应调节因子，它由两个不同的结构域组成，N-末端接收结构域和C-末端输出结构域，其结合DNA并与σ（70）相互作用以激活Pho调节子的转录。磷酸化激活的机制尚未确定。为了更好地理解接收器结构域在控制输出结构域的活性中的功能，在未磷酸化的PhoB和其孤立的DNA结合结构域（PhoB（DBD））之间进行DNA结合和转录激活的直接比较。使用荧光各向异性，发现PhoB（DBD）以比未磷酸化的PhoB大七倍的健全性结合到pho盒。还发现PhoB（DBD）比全长未修饰的蛋白质能够更好地激活转录。我们的结论是，非磷酸化的接收域的PhoB沉默其输出域的活动。这些结果表明，在磷酸化的接收器域的PhoB，抑制放置在输出域被解除的构象变化，改变未磷酸化的接收器域和输出域之间的相互作用。
PhoB is the response regulator of the Pho regulon, It is composed of two distinct domains, an N-terminal receiver domain and a C-terminal output domain that binds DNA and interacts with sigma (70) to activate transcription of the Pho regulon, Phosphorylation of the receiver domain is required for activation of the protein. The mechanism of activation by phosphorylation has not yet been determined. To better understand the function of the receiver domain in controlling the activity of the output domain, a direct comparison was made between unphosphorylated PhoB and its solitary DNA-binding domain (PhoB(DBD)) for DNA binding and transcriptional activation. Using fluorescence anisotropy, it was found that PhoB(DBD) bound to the pho box with an sanity seven times greater than that of unphosphorylated PhoB. It was also found that PhoB(DBD) was better able to activate transcription than the full-length, unmodified protein. We conclude that the unphosphorylated receiver domain of PhoB silences the activity of its output domain. These results suggest that upon phosphorylation of the receiver domain of PhoB, the inhibition placed upon the output domain is relieved by a conformational change that alters interactions between the unphosphorylated receiver domain and the output domain.