Hagan C E, Warren G J
Gene. 1983 Oct;24(2-3):317-26. doi: 10.1016/0378-1119(83)90092-6.
Palindromic arrangements of 2 X 400 to 2 X 1517 bp of nucleotide sequences were created by in vitro manipulation of Escherichia coli plasmids. As a consequence of its method of formation, each palindrome possessed at its center the recognition site for a particular restriction endonuclease. Eight out of eight palindromes, having at their centers the recognition sites for BamHI, BglI, BglII, HindIII, PstI, SalI, XhoI, and Xma III, were shown to be inviable when transformed into E. coli. The smallest of these palindromes had a half-length of approx. 400 bp. The lethality of palindromic sequences for their carrier plasmids was circumvented at low frequencies by spontaneous in vivo deletion events which removed the centers of symmetry of the palindromes. The frequencies of such deletions were less than 1% in most cases, but varied significantly both with the palindromic sequence in question and with the surrounding nonpalindromic sequences of the carrier plasmid. We confirmed the viability of a plasmid with a 147-bp palindrome [Bergsma et al., Gene 20 (1982) 157-167] and found that this palindrome (derived from SV40) does not confer viability on the plasmids with long palindromes.
通过对大肠杆菌质粒进行体外操作，构建了核苷酸序列为2×400至2×1517 bp的回文排列。由于其形成方法，每个回文在其中心都具有特定限制性内切酶的识别位点。当转化到大肠杆菌中时，八个回文中的八个（其中心分别为BamHI、BglI、BglII、HindIII、PstI、SalI、XhoI和Xma III的识别位点）被证明是不可存活的。这些回文中最小的回文半长约为400 bp。回文序列对其载体质粒的致死性在低频情况下通过体内自发缺失事件得以规避，这些缺失事件去除了回文的对称中心。在大多数情况下，此类缺失的频率小于1%，但随所讨论的回文序列以及载体质粒的周围非回文序列而有显著变化。我们证实了带有147 bp回文的质粒的存活能力[Bergsma等人，《基因》20（1982年）157 - 167]，并发现这个回文（源自SV40）不会赋予带有长回文的质粒存活能力。
