Robinson P J, Cranenburgh R M, Head I M, Robinson N J
Department of Biochemistry and Genetics, University of Newcastle, UK.
Mol Microbiol. 1997 Apr;24(1):181-9. doi: 10.1046/j.1365-2958.1997.3391695.x.
The sequence 5'-GCGATCGC-3', designated HIP1, for highly iterated palindrome, was first identified at the borders of a gene-deletion event and subsequently shown to constitute up to 2.5% of the DNA in some cyanobacteria. It is now reported that HIP1 is polyphyletic, occurring in several distinct cyanobacterial lineages and not defining a clade. HIP1 does not introduce gaps into sequence alignments. It aligns with partial HIP1 sites in related sequences showing that it propagates by nucleotide substitutions rather than insertion. Constructs have been created to determine the frequencies at which deletion events occur between palindromes located within the selectable marker neo. Deletion between HIP1 sites was more frequent in Synechococcus PCC 7942 than deletion between control palindromes, 5'-CCGATCGG-3', designated PAL0. However, this is not due to a recombinase that recognises HIP1 and is peculiar to cyanobacteria because similar deletion frequencies were detected in Escherichia coli. Furthermore, the frequency of deletion of DNA flanked asymmetrically by one HIP1 site and one PAL0 site was less than the frequency of deletion of DNA flanked asymmetrically by identical copies of either palindrome. This is consistent with deletion by copy-choice.
序列5'-GCGATCGC-3'，命名为HIP1（高度重复回文序列），最初是在一个基因缺失事件的边界处被识别出来的，随后发现它在某些蓝藻中占DNA的比例高达2.5%。现在有报道称HIP1是多系起源的，存在于几个不同的蓝藻谱系中，并不定义一个进化枝。HIP1不会在序列比对中引入缺口。它与相关序列中的部分HIP1位点对齐，表明它是通过核苷酸替换而不是插入来传播的。已经构建了一些结构来确定位于选择标记neo内的回文序列之间发生缺失事件的频率。在聚球藻PCC 7942中，HIP1位点之间的缺失比对照回文序列5'-CCGATCGG-3'（命名为PAL0）之间的缺失更频繁。然而，这并不是由于一种识别HIP1且蓝藻特有的重组酶，因为在大肠杆菌中也检测到了类似的缺失频率。此外，由一个HIP1位点和一个PAL0位点不对称侧翼的DNA的缺失频率低于由任何一种回文序列的相同拷贝不对称侧翼的DNA的缺失频率。这与通过模板选择进行缺失是一致的。
