同型嘧啶寡聚物与双链DNA同源区域之间的稳定复合物。

A stable complex between homopyrimidine oligomers and the homologous regions of duplex DNAs.

作者信息

Lyamichev V I, Mirkin S M, Frank-Kamenetskii M D, Cantor C R

机构信息

Institute of Molecular Genetics, USSR Academy of Sciences, Moscow.

出版信息

Nucleic Acids Res. 1988 Mar 25;16(5):2165-78. doi: 10.1093/nar/16.5.2165.

When plasmid DNA duplexes carrying the regular homopurine-homopyrimidine inserts (dGA)n, (dTC)n and (dG)n, (dC)n are preincubated with homologous labeled oligo(dPy) ((dTC)n and (dC)n respectively) at acid pH, the label co-electrophoreses with the duplex DNA. Thus, a very strong complex is formed. Complementary oligo(dPu) does not form a complex under these conditions. No binding is observed for oligo(dPy) with non-homologous inserts as well as with vector plasmids without inserts. The complex is formed equally well with linear, nicked or superhelical DNA. The complex is not detected at pH greater than 6. Complex formation leads to very little, if any, unwinding of the duplex. The observed complex appears to be the Py.Pu.Py triplex consisting of TAT and CGC base-triads with protonated cytosines. Two-dimensional gel electrophoresis patterns show that the presence of homologous oligo(dPy) destabilizes the formation of the H form.

当携带规则的同型嘌呤-同型嘧啶插入片段（dGA）n、（dTC）n以及（dG）n、（dC）n的质粒DNA双链在酸性pH条件下与同源标记的寡聚（dPy）（分别为（dTC）n和（dC）n）预孵育时，标记物与双链DNA共电泳。因此，形成了一种非常强的复合物。在这些条件下，互补的寡聚（dPu）不会形成复合物。对于带有非同源插入片段的寡聚（dPy）以及没有插入片段的载体质粒，未观察到结合现象。该复合物与线性、带切口或超螺旋DNA形成的情况一样好。在pH大于6时未检测到该复合物。复合物的形成导致双链极少解旋（如果有解旋的话）。观察到的复合物似乎是由TAT和CGC碱基三联体以及质子化胞嘧啶组成的Py.Pu.Py三链体。二维凝胶电泳图谱表明，同源寡聚（dPy）的存在会破坏H型结构的形成。