Cornet F, Mortier I, Patte J, Louarn J M
Laboratoire de Microbiologie et de Génétique Moléculaires, Centre National de la Recherche Scientifique, Toulouse, France.
J Bacteriol. 1994 Jun;176(11):3188-95. doi: 10.1128/jb.176.11.3188-3195.1994.
Plasmid pSC101 harbors a 28-bp sequence which is homologous to dif, the target site of the XerC/XerD-dependent recombination system in Escherichia coli. Using a technique which allows very sensitive detection of plasmid loss, we show that recombination at this site, termed psi for pSC101 stabilized inheritance, causes a moderate increase in pSC101 stability. The role of the psi sequence in site-specific recombination has been explored in two other contexts. It was cloned in a derivative of plasmid p15A and inserted into the chromosome in place of dif. In the first situation, psi activity requires accessory sequences and results in multimer resolution; in the second situation, it suppresses the effects of the dif deletion and can promote intermolecular exchanges. Thus, psi is a site whose recombinational activity depends on the context, the first in the cer/dif family known to exhibit such flexibility.
质粒pSC101含有一段28个碱基对的序列，该序列与大肠杆菌中XerC/XerD依赖性重组系统的靶位点dif同源。我们使用一种能够非常灵敏地检测质粒丢失的技术，证明了在此位点（称为psi，用于pSC101稳定遗传）发生的重组会使pSC101的稳定性适度增加。psi序列在位点特异性重组中的作用已在另外两种情况下进行了探索。它被克隆到质粒p15A的一个衍生物中，并代替dif插入到染色体中。在第一种情况下，psi活性需要辅助序列并导致多聚体的拆分；在第二种情况下，它抑制dif缺失的影响并可促进分子间交换。因此，psi是一个重组活性取决于环境的位点，这是cer/dif家族中已知的第一个表现出这种灵活性的位点。
