Backbone dynamics of the c-Myb DNA-binding domain complexed with a specific DNA.
Backbone dynamics of the c-Myb DNA-binding domain complexed with a specific DNA.
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c-Myb DNA 结合结构域与特定 DNA 复合的主链动力学。
DOI：
10.1093/oxfordjournals.jbchem.a022710
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发表时间：
2000
影响因子：
2.7
通讯作者：
Y. Nishimura
中科院分区：
文献类型：
--
作者：
M. Sasaki;K. Ogata;H. Hatanaka;Y. Nishimura
c-Myb的DNA结合结构域由三个不完全串联重复序列R1、R2和R3组成。每个重复序列含有三个螺旋。最小的DNA结合结构域是R2 R3片段。在这里，我们研究了骨架动力学的R2 R3在其DNA结合的形式，通过NMR。在与DNA结合时，N-和C-末端以及R2和R3之间的接头变得不那么灵活。在自由形式的第三螺旋的R2表现出缓慢的构象交换波动，由于在R2的疏水核心的空腔。在结合到DNA，构象交换贡献R2减少，但仍然显着的NMR弛豫测量。在与DNA结合时，R3的第三螺旋表现出显着的化学交换贡献。这些发现表明，R2和R3的第三个螺旋的方向的DNA是化学交换。在DNA结合形式中，R2和R3表现出相似的动力学特征，除了R2的氨基酸Trp 95、Thr 96和瓦尔103位于未结合形式的空腔周围。在与DNA结合时，由于Trp 95移动到空腔中以填充它，因此在填充的空腔周围似乎仍然可以观察到局部构象交换贡献。
The DNA-binding domain of c-Myb consists of three imperfect tandem repeats, R1, R2, and R3. Each repeat contains three helices. The minimal DNA-binding domain is an R2R3 fragment. Here, we have examined the backbone dynamics of R2R3 in its DNA-bound form by NMR. Upon binding to DNA, the N- and C-termini, and the linker between R2 and R3 become less flexible. In the free form the third helix of R2 exhibits slow conformational exchange fluctuations owing to a cavity in the hydrophobic core of R2. Upon binding to DNA, the conformational exchange contributions in R2 are reduced but remain significant in NMR relaxation measurements. Upon binding to DNA, the third helix of R3 comes to exhibit significant chemical exchange contributions. These findings suggest that the orientations of the third helices of both R2 and R3 as to DNA are being chemically exchanged. In the DNA-bound form both R2 and R3 exhibit similar dynamical characters, except for amino acids Trp 95, Thr 96, and Val 103 of R2, which are located around the cavity of the unbound form. Upon binding to DNA, since Trp 95 moves into the cavity to fill it up, the local conformational exchange contributions seem to be still observable around the filled cavity.