Bear D G, Ng R, Van Derveer D, Johnson N P, Thomas G, Schleich T, Noller H F
Proc Natl Acad Sci U S A. 1976 Jun;73(6):1824-8. doi: 10.1073/pnas.73.6.1824.
Ribosomal 30S protein S1 causes disruption of the secondary structure of certain pyrimidine-containing polynucleotides. Helical poly(U), poly(C, U), and neutral and acidic poly(C) are stoichiometrically converted by S1 to structures indistinguishable from their partially or completely thermally denatured forms, as revealed by circular dichroism. Of the several double- and triple-stranded helical polynucleotides tested that contain one polypurine strand and at least one polypyrimidine strand, only the conformation of the DNA.RNA hybrid, poly(A)-poly(dT), is perturbed. In the presence of S1, this hybrid undergoes a transition to a new structure that has a circular dichroism spectrum unlike either the native or thermally denatured forms. Intercalated ethidium bromide is released from poly(A)-poly(dT) by S1, confirming the occurrence of a conformational rearrangement. The translation inhibitor, autintricarboxylic acid, completely inhibits the action of S1 on polypyrimidines, but has no effect on the conformational perturbation of poly(A(-poly(dT). The possible relation between these observations and the biological function of protein S1 is discussed.
核糖体30S蛋白S1可导致某些含嘧啶多核苷酸二级结构的破坏。圆二色性显示，螺旋状的聚尿苷酸、聚（胞嘧啶，尿嘧啶）以及中性和酸性聚胞嘧啶被S1化学计量地转化为与其部分或完全热变性形式无法区分的结构。在测试的几种包含一条聚嘌呤链和至少一条聚嘧啶链的双链和三链螺旋多核苷酸中，只有DNA.RNA杂交体聚（A）-聚（dT）的构象受到干扰。在S1存在的情况下，这种杂交体转变为一种新结构，其圆二色光谱既不同于天然形式，也不同于热变性形式。嵌入的溴化乙锭被S1从聚（A）-聚（dT）中释放出来，证实了构象重排的发生。翻译抑制剂金精三羧酸完全抑制S1对聚嘧啶的作用，但对聚（A）-聚（dT）的构象扰动没有影响。本文讨论了这些观察结果与蛋白S1生物学功能之间的可能关系。
