Identification of the residues in the Myb domain of maize C1 that specify the interaction with the bHLH cofactor R
Identification of the residues in the Myb domain of maize C1 that specify the interaction with the bHLH cofactor R
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DOI：
10.1073/pnas.250379897
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发表时间：
2000-12-05
影响因子：
11.1
通讯作者：
Chandler, VL
中科院分区：
文献类型：
--
作者：
Grotewold, E;Sainz, MB;Chandler, VL
玉米Myb转录因子C1依赖碱性螺旋-环-螺旋（bHLH）蛋白R或B来调节功能，但密切相关的Myb蛋白P不依赖。我们利用C1和P的Myb结构域之间的相似性来识别指定C1的Myb结构域与r的n端区域之间相互作用的残基。将P的第二个Myb重复序列的第一个螺旋中的四个预测的溶剂暴露残基替换为C1的相应残基足以赋予P与r物理相互作用的能力。在玉米细胞中，需要两个额外的Myb结构域氨基酸改变，使P的调节活性部分依赖于R。有趣的是，当P发生改变使其与R相互作用时，它可以激活Bz1启动子，通常由C1 + R而不是P调节。总之，这些发现表明，高度相似的Myb结构域内的一些氨基酸的变化可以介导与在C1调节特异性中起核心作用的转录共调节因子的差异相互作用，并且Myb结构域在组合转录调节中起重要作用。
The maize Myb transcription factor C1 depends on the basic helix-loop-helix (bHLH) proteins R or B for regulatory function, but the closely related Myb protein P does not. We have used the similarity between the Myb domains of C1 and P to identify residues that specify the interaction between the Myb domain of C1 and the N-terminal region of R. Substitution of four predicted solvent-exposed residues in the first helix of the second Myb repeat of P with corresponding residues from C1 is sufficient to confer on P the ability to physically interact with R. However, two additional Myb domain amino acid changes are needed to make the P regulatory activity partially dependent on R in maize cells. Interestingly, when P is altered so that it interacts with R, it can activate the Bz1 promoter, normally regulated by C1 + R but not by P. Together, these findings demonstrate that the change of a few amino acids within highly similar Myb domains can mediate differential interactions with a transcriptional coregulator that plays a central role in the regulatory specificity of C1, and that Myb domains play important roles in combinatorial transcriptional regulation.