Albert A C, Roman A M, Bouche G, Leng M, Rahmouni A R
Centre de Biophysique Moléculaire, CNRS, Orléans, France.
J Biol Chem. 1994 Jul 29;269(30):19238-44.
The structural transition of an alternating purine-pyrimidine sequence (CG)5(TG)28) from the 5'-untranscribed region of the mouse ribosomal DNA was analyzed by two-dimensional gel electrophoresis and chemical probes. The repeat undergoes a supercoil-dependent gradual and oriented B-Z transition. At a threshold level of negative supercoiling, a limited region of the repeat encompassing the (CG)5 motif converts cooperatively into Z-DNA. As the superhelical stress increases, the Z-structure propagates along the remaining part of the repeat by successive transitions until the full-length sequence is converted. By in situ OsO4 probing experiments, we show also that this (TG)n-containing repeat adopts the Z-structure in Escherichia coli.
通过二维凝胶电泳和化学探针分析了小鼠核糖体DNA 5'-非转录区交替嘌呤-嘧啶序列（CG）5（TG）28的结构转变。该重复序列经历超螺旋依赖性的渐进且定向的B-Z转变。在负超螺旋达到阈值水平时，包含（CG）5基序的重复序列的有限区域协同转变为Z-DNA。随着超螺旋应力增加，Z结构通过连续转变沿着重复序列的其余部分传播直至全长序列被转变。通过原位OsO4探测实验，我们还表明这种含（TG）n重复序列在大肠杆菌中采用Z结构。
