Exploring the role of glutamine 50 in the homeodomain-DNA interface:: Crystal structure of engrailed (Gln50 → Ala) complex at 2.0 Å
Exploring the role of glutamine 50 in the homeodomain-DNA interface:: Crystal structure of engrailed (Gln50 → Ala) complex at 2.0 Å
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DOI：
10.1021/bi000071a
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发表时间：
2000-07-18
期刊：
影响因子：
2.9
通讯作者：
Pabo, CO
中科院分区：
文献类型：
--
作者：
Grant, RA;Rould, MA;Pabo, CO
我们以2.0埃的分辨率确定了含有与野生型最佳DNA位点（TAATTA）结合的交错同源结构域Gln 50-> Ala变体（QA 50）的复合物的晶体结构。其他研究小组的生物化学和遗传学研究表明，残基50是同源结构域之间差异DNA结合特异性的重要决定因素（在一般形式TAATNN的各种位点之间进行区分）。然而，对QA 50变体的生物化学研究表明，它几乎与野生型蛋白质一样紧密结合，并且特异性只有适度的变化。我们现在已经确定了QA 50变体的晶体结构，以帮助理解残基50在位点特异性识别中的作用。我们的共晶结构显示了一些有趣的变化，在水的结构在网站的取代，并显示了一些变化，在相邻的侧链的构象。然而，结构，如QA 50的生化数据，表明Gln 50在确定的亲和力和特异性的盘根错节的同源结构域中发挥相对适度的作用。
We have determined the crystal structure of a complex containing the engrailed homeodomain Gln50 --> Ala variant (QA50) bound to the wild-type optimal DNA site (TAATTA) at 2.0 Angstrom resolution. Biochemical and genetic studies by other groups have suggested that residue 50 is an important determinant of differential DNA-binding specificity among homeodomains (distinguishing among various sites of the general form TAATNN). However, biochemical studies of the QA50 variant had revealed that it binds almost as tightly as the wild-type protein and with only modest changes in specificity. We have now determined the crystal structure of the QA50 variant to help understand the role of residue 50 in site-specific recognition. Our cocrystal structure shows some interesting changes in the water structure at the site of the substitution and shows some changes in the conformations of neighboring side chains. However, the structure, like the QA50 biochemical data, suggests that Gln50 plays a relatively modest role in determining the affinity and specificity of the engrailed homeodomain.