Circles: The replication-recombination-chromosome segregation connection
Circles: The replication-recombination-chromosome segregation connection
复制标题
DOI：
10.1073/pnas.111008998
复制
发表时间：
2001-07-17
影响因子：
11.1
通讯作者：
Sherratt, D
中科院分区：
文献类型：
--
作者：
Barre, FX;Soballe, B;Sherratt, D
通过单体圆形染色体之间的同源重组越过，会产生二聚体圆形染色体，在细胞分裂过程中不能隔离到子细胞。在大肠杆菌中，同源重组是有偏见的，因此大多数同源重组事件都会产生非交叉的单体圆形染色体。这种偏见在RUV突变体中丧失。一种新型的蛋白质RARA，在精杆菌和真核生物中高度保守，与RUVB和DNAX蛋白有关，Gamma和Tau（1）可能会影响交叉重组的形成。那些形成形成的二聚体染色体通过XER位点特异性重组在重组位点DIF（位于大肠杆菌染色体的复制末端区域）中转化为单体。隔离的FTSK蛋白将细胞分裂与染色体隔离相协调，需要在DIF处进行完整的XER重组反应。只有在染色体二聚体中正确定位的差异位置才能访问隔分离的FTSK。 FTSK通过促进由XERC重组酶形成的XER重组中间体的XER重组中间体的构象变化起作用。这种变化为XERD提供了一个基板，然后完成重组反应。
Crossing over by homologous recombination between monomeric circular chromosomes generates dimeric circular chromosomes that cannot be segregated to daughter cells during cell division. In Escherichia coli, homologous recombination is biased so that most homologous recombination events generate noncrossover monomeric circular chromosomes. This bias is lost in ruv mutants. A novel protein, RarA, which is highly conserved in eubacteria and eukaryotes and is related to the RuvB and the DnaX proteins, gamma and tau (1) may influence the formation of crossover recombinants. Those dimeric chromosomes that do form are converted to monomers by Xer site-specific recombination at the recombination site dif, located in the replication terminus region of the E. coli chromosome. The septum-located FtsK protein, which coordinates cell division with chromosome segregation, is required for a complete Xer recombination reaction at dif. Only correctly positioned dif sites present in a chromosomal dimer are able to access septum-located FtsK. FtsK acts by facilitating a conformational change in the Xer recombination Holliday junction intermediate formed by XerC recombinase. This change provides a substrate for XerD which then completes the recombination reaction.