Hagerman P J
Department of Biochemistry, Biophysics, and Genetics, University of Colorado Health Sciences Center, Denver 80262.
Biochemistry. 1990 Feb 27;29(8):1980-3. doi: 10.1021/bi00460a003.
DNA containing short sequences of the form (dA)n.(dT)n can exhibit pronounced degrees of stable curvature of the helix axis, provided that these homooligomeric stretches are approximately in phase with the helix repeat. However, the precise origin of this effect is unknown. We have observed that pyrimidine 5-methyl groups can have a significant effect on the degree of curvature, depending on their locations within the homooligomeric sequences. Such effects are observed in both (dA)n.(dT/dU)n and (dI)n.(dC/d5meC)n sequence motifs, arguing for a general structural perturbation due to the methyl group. The current observations suggest that pyrimidine methyl groups could influence protein-DNA interactions not only through direct protein-methyl group contacts but also by methyl group induced alterations in local DNA structure.
含有(dA)n.(dT)n形式短序列的DNA能够呈现出明显程度的螺旋轴稳定曲率，前提是这些同聚寡核苷酸片段与螺旋重复序列大致同相。然而，这种效应的确切起源尚不清楚。我们观察到嘧啶5-甲基基团对曲率程度有显著影响，这取决于它们在同聚寡核苷酸序列中的位置。在(dA)n.(dT/dU)n和(dI)n.(dC/d5meC)n序列基序中均观察到此类效应，这表明甲基基团会引起普遍的结构扰动。当前的观察结果表明，嘧啶甲基基团不仅可以通过蛋白质与甲基基团的直接接触，还可以通过甲基基团诱导的局部DNA结构改变来影响蛋白质与DNA的相互作用。
