噬菌体T7中直接重复序列的长度及回文序列的存在对直接重复DNA序列间缺失的影响。
The effect of the length of direct repeats and the presence of palindromes on deletion between directly repeated DNA sequences in bacteriophage T7.
作者信息
Pierce J C, Kong D, Masker W
机构信息
Department of Biochemistry and Molecular Biology, Temple University School of Medicine, Philadelphia, PA 19140.
出版信息
Nucleic Acids Res. 1991 Jul 25;19(14):3901-5. doi: 10.1093/nar/19.14.3901.
The frequency of genetic deletion between directly repeated DNA sequences in bacteriophage T7 was measured as a function of the length of the direct repeat. The non-essential ligase gene (gene 1.3) of bacteriophage T7 was interrupted with pieces of synthetic DNA bracketed by direct repeats of various lengths. Deletion of these 76 bp long inserts was too low to be measured when the direct repeats were less than 6 bp long. However, the frequency of deletion of inserts with longer direct repeats increased exponentially as the length of the repeats increased from 8 to 20 bp. When inverted repeats (palindromes) were designed in the midst of the insert there was essentially no increase in deletion frequency between 10 bp direct repeats. But, the same palindromic sequences increased the deletion frequency between 5 bp direct repeats by at least two orders of magnitude. Thus, in this system homology at the endpoints is a more important determinant of deletion frequency than is the presence of palindromes between the direct repeats.
测量了噬菌体T7中直接重复DNA序列之间基因缺失的频率，并将其作为直接重复长度的函数。噬菌体T7的非必需连接酶基因（基因1.3）被不同长度直接重复序列包围的合成DNA片段打断。当直接重复序列长度小于6 bp时，这些76 bp长插入片段的缺失率过低而无法测量。然而，随着重复序列长度从8 bp增加到20 bp，具有更长直接重复序列的插入片段的缺失频率呈指数增加。当在插入片段中间设计反向重复序列（回文序列）时，10 bp直接重复序列之间的缺失频率基本没有增加。但是，相同的回文序列使5 bp直接重复序列之间的缺失频率至少增加了两个数量级。因此，在这个系统中，端点处的同源性比直接重复序列之间回文序列的存在更能决定缺失频率。
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