Restriction of the activity recombination site dif to a small zone of the Escherichia coli chromosome
Restriction of the activity recombination site dif to a small zone of the Escherichia coli chromosome
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DOI：
10.1101/gad.10.9.1152
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发表时间：
1996-05-01
影响因子：
10.5
通讯作者：
Louarn, JM
中科院分区：
文献类型：
--
作者：
Cornet, F;Louarn, J;Louarn, JM
重组位点 diff 是位点特异性重组酶 XerC 和 XerD 的大肠杆菌染色体上的靶标。 diff/XerC-D 系统在细胞周期中发挥作用，可能是通过有利于姐妹染色体单体化或分离。本期还分析了对 diff 活动的区域控制现象，通过将 diff 易位到一系列接近正常基因座的基因座来证明。我们发现该位点仅在其自然位置周围的狭窄区域内具有生理活性。 dif 活性的能力不依赖于正常 dif 活性区 (DAZ) 的序列，因为当 dif 重新插入连接点时，大于 DAZ 的 Delta(dif) 缺失会导致 Dif(+) 细菌。尽管 diff 映射了复制通常终止的位置，但复制终止并不是引发子。具有大倒位的菌株将 diff 及其周围区域置于 oriC 附近，即使 Tus(-) 突变允许复制在远离它的地方终止，但仍保持 Dif(+)。初步数据表明，特殊序列可能将感受态区与染色体的其余部分分开。我们怀疑这些序列是参与核样结构复制后重建的极化过程的一组序列的成员。我们提出，这种重建迫使姐妹染色体之间的串联连接在 DAZ 内积累，最终有利于在 diff 处重组。
The recombination site dif is the target on the Escherichia coli chromosome of the site-specific recombinases XerC and XerD. The dif/XerC-D system plays a role during the cell cycle, probably by favoring sister chromosome monomerization or separation. A phenomenon of regional control over dif activity, also analyzed in this issue, is demonstrated here by translocation of dif to a series of loci close to the normal locus. We found that the site is physiologically active only within a narrow zone around its natural position. Competence for dif activity does not depend on the sequence of the normal dif activity zone (DAZ), because Delta(dif) deletions larger than the DAZ result in Dif(+) bacteria when dif is reinserted at the junction point. Although dif maps where replication normally terminates, termination of replication is not the elicitor. A strain with a large inversion that places dif and its surrounding region close to oriC remains Dif(+), even when a Tus(-) mutation allows replication to terminate far away from it. Preliminary data suggest the possibility that specialized sequences separate the competent zone from the rest of the chromosome. We suspect that these sequences are members of a set of sequences involved in a polarized process of postreplicative reconstruction of the nucleoid structure. We propose that this reconstruction forces catenation links between sister chromosomes to accumulate within the DAZ, where they eventually favor recombination at dif.