DasGupta U, Weston-Hafer K, Berg D E
Genetics. 1987 Jan;115(1):41-9. doi: 10.1093/genetics/115.1.41.
The specificity of deletion formation was studied using tests involving reversion of palindromic insertion mutations. Insertions of a Tn5-related transposon at 13 sites in the ampicillin-resistance (amp) gene of plasmid pBR322 were shortened to a nested set of perfect palindromes, 22, 32 and 90 bp long. We monitored frequencies of reversion to Ampr, which is the result of deletion of the palindrome plus one copy of the flanking 9 bp direct repeats (which had been formed by transposition). Revertant frequencies were found to depend on the location and the sequence of the palindromic insert. Changing a 45-kb interrupted palindrome to a 22-bp perfect palindrome stimulated deletion formation by factors of from fourfold to 545-fold among the 13 sites, while elongation of the perfect palindrome from 22 to 90 bp stimulated deletion formation by factors of from eight- to 18,000-fold. We conclude that deletion formation is strongly affected by subtle features of DNA sequence or conformation, both inside and outside the deleted segment, and that these effects may reflect specific interactions of DNA processing proteins with template DNAs.
利用涉及回文插入突变回复的试验研究了缺失形成的特异性。在质粒pBR322的氨苄青霉素抗性（amp）基因的13个位点插入与Tn5相关的转座子，这些插入被缩短为一组嵌套的完美回文序列，长度分别为22、32和90 bp。我们监测了回复到Ampr的频率，这是回文序列缺失加上侧翼9 bp直接重复序列的一个拷贝（由转座形成）的结果。发现回复频率取决于回文插入的位置和序列。将一个45 kb的中断回文序列变为22 bp的完美回文序列，在13个位点中刺激缺失形成的倍数从4倍到545倍不等，而将完美回文序列从22 bp延长到90 bp，刺激缺失形成的倍数从8倍到18000倍不等。我们得出结论，缺失形成受到缺失片段内外DNA序列或构象细微特征的强烈影响，并且这些影响可能反映了DNA加工蛋白与模板DNA的特异性相互作用。
