CAP对DNA序列的识别：DNA位点碱基对6中腺嘌呤N6原子的作用。
DNA-sequence recognition by CAP: role of the adenine N6 atom of base pair 6 of the DNA site.
作者信息
Gunasekera A, Ebright Y W, Ebright R H
机构信息
Department of Chemistry, Rutgers University, New Brunswick, NJ.
出版信息
Nucleic Acids Res. 1990 Dec 11;18(23):6853-6. doi: 10.1093/nar/18.23.6853.
Two similar, but not identical, models have been proposed for the amino acid-base pair contacts in the CAP-DNA complex ('Model I,' Weber, I. and Steitz, T., Proc. Natl. Acad. Sci. USA, 81, 3973-3977, 1984; 'Model II,' Ebright, et al., Proc. Natl. Acad. Sci. USA, 81, 7274-7278, 1984). One difference between the two models involves Glu181 of CAP. Model I predicts that Glu181 of CAP makes two specificity determining contacts: one H-bond with the cytosine N4 atom of G:C at base pair 7 of the DNA half site, and one H-bond with the adenine N6 atom of T:A at base pair 6 of the DNA half site. In contrast, Model II predicts that Glu181 makes only one specificity determining contact: one H-bond with the cytosine N4 atom of G:C at base pair 7 of the DNA half site. In the present work, we show that replacement of T:A at base pair 6 of the DNA half site by T:N6-methyl-adenine has no, or almost no, effect on the binding of CAP. We conclude, contrary to Model I, that Glu181 of CAP makes no contact with the adenine N6 atom of base pair 6 of the DNA half site.
针对CAP-DNA复合物中的氨基酸-碱基对相互作用，已经提出了两个相似但并不完全相同的模型（“模型I”，Weber, I.和Steitz, T.，《美国国家科学院院刊》，81, 3973 - 3977, 1984；“模型II”，Ebright等人，《美国国家科学院院刊》，81, 7274 - 7278, 1984）。这两个模型的一个差异涉及CAP的Glu181。模型I预测，CAP的Glu181形成两个决定特异性的相互作用：一个氢键与DNA半位点碱基对7处G:C的胞嘧啶N4原子形成，另一个氢键与DNA半位点碱基对6处T:A的腺嘌呤N6原子形成。相比之下，模型II预测Glu181仅形成一个决定特异性的相互作用：一个氢键与DNA半位点碱基对7处G:C的胞嘧啶N4原子形成。在本研究中，我们表明，将DNA半位点碱基对6处的T:A替换为T:N6-甲基腺嘌呤对CAP的结合没有或几乎没有影响。我们得出结论，与模型I相反，CAP的Glu181不与DNA半位点碱基对6的腺嘌呤N6原子形成相互作用。
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