Sherratt David J, Søballe Britta, Barre François-Xavier, Filipe Sergio, Lau Ivy, Massey Thomas, Yates James
Division of Molecular Genetics, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
Philos Trans R Soc Lond B Biol Sci. 2004 Jan 29;359(1441):61-9. doi: 10.1098/rstb.2003.1365.
The duplication of DNA and faithful segregation of newly replicated chromosomes at cell division is frequently dependent on recombinational processes. The rebuilding of broken or stalled replication forks is universally dependent on homologous recombination proteins. In bacteria with circular chromosomes, crossing over by homologous recombination can generate dimeric chromosomes, which cannot be segregated to daughter cells unless they are converted to monomers before cell division by the conserved Xer site-specific recombination system. Dimer resolution also requires FtsK, a division septum-located protein, which coordinates chromosome segregation with cell division, and uses the energy of ATP hydrolysis to activate the dimer resolution reaction. FtsK can also translocate DNA, facilitate synapsis of sister chromosomes and minimize entanglement and catenation of newly replicated sister chromosomes. The visualization of the replication/recombination-associated proteins, RecQ and RarA, and specific genes within living Escherichia coli cells, reveals further aspects of the processes that link replication with recombination, chromosome segregation and cell division, and provides new insight into how these may be coordinated.
DNA的复制以及新复制的染色体在细胞分裂时的忠实分离常常依赖于重组过程。断裂或停滞的复制叉的重建普遍依赖于同源重组蛋白。在具有环状染色体的细菌中，同源重组导致的交叉会产生二聚体染色体，除非它们在细胞分裂前通过保守的Xer位点特异性重组系统转化为单体，否则无法分离到子细胞中。二聚体的拆分还需要FtsK，一种位于分裂隔膜上的蛋白质，它将染色体分离与细胞分裂协调起来，并利用ATP水解的能量激活二聚体拆分反应。FtsK还可以转运DNA，促进姐妹染色体的联会，并使新复制的姐妹染色体的缠结和连环化降至最低。对活的大肠杆菌细胞内与复制/重组相关的蛋白质RecQ和RarA以及特定基因的可视化，揭示了将复制与重组、染色体分离和细胞分裂联系起来的过程的更多方面，并为这些过程如何协调提供了新的见解。
