Bigot Sarah, Saleh Omar A, Lesterlin Christian, Pages Carine, El Karoui Meriem, Dennis Cynthia, Grigoriev Mikhail, Allemand Jean-François, Barre François-Xavier, Cornet François
LMGM, CNRS, 118, route de Narbonne, Toulouse, France.
EMBO J. 2005 Nov 2;24(21):3770-80. doi: 10.1038/sj.emboj.7600835. Epub 2005 Oct 6.
Bacterial chromosomes are organized in replichores of opposite sequence polarity. This conserved feature suggests a role in chromosome dynamics. Indeed, sequence polarity controls resolution of chromosome dimers in Escherichia coli. Chromosome dimers form by homologous recombination between sister chromosomes. They are resolved by the combined action of two tyrosine recombinases, XerC and XerD, acting at a specific chromosomal site, dif, and a DNA translocase, FtsK, which is anchored at the division septum and sorts chromosomal DNA to daughter cells. Evidences suggest that DNA motifs oriented from the replication origin towards dif provide FtsK with the necessary information to faithfully distribute chromosomal DNA to either side of the septum, thereby bringing the dif sites together at the end of this process. However, the nature of the DNA motifs acting as FtsK orienting polar sequences (KOPS) was unknown. Using genetics, bioinformatics and biochemistry, we have identified a family of DNA motifs in the E. coli chromosome with KOPS activity.
细菌染色体以相反序列极性的复制子形式组织。这一保守特征表明其在染色体动态变化中发挥作用。事实上，序列极性控制大肠杆菌中染色体二聚体的解离。染色体二聚体通过姐妹染色体之间的同源重组形成。它们通过两种酪氨酸重组酶XerC和XerD在特定染色体位点dif的联合作用以及一种DNA转位酶FtsK来解离，FtsK锚定在分裂隔膜上并将染色体DNA分配到子细胞中。有证据表明，从复制起点朝向dif的DNA基序为FtsK提供了必要信息，使其能够将染色体DNA忠实地分配到隔膜两侧，从而在此过程结束时将dif位点聚集在一起。然而，作为FtsK定向极性序列（KOPS）的DNA基序的性质尚不清楚。通过遗传学、生物信息学和生物化学方法，我们在大肠杆菌染色体中鉴定出了具有KOPS活性的一类DNA基序。
