Babic Ana, Lindner Ariel B, Vulic Marin, Stewart Eric J, Radman Miroslav
INSERM U571, Paris F-75015, France.
Science. 2008 Mar 14;319(5869):1533-6. doi: 10.1126/science.1153498.
Conjugation allows bacteria to acquire genes for antibiotic resistance, novel virulence attributes, and alternative metabolic pathways. Using a fluorescent protein fusion, SeqA-YFP, we have visualized this process in real time and in single cells of Escherichia coli. We found that the F pilus mediates DNA transfer at considerable cell-to-cell distances. Integration of transferred DNA by recombination occurred in up to 96% of recipients; in the remaining cells, the transferred DNA was fully degraded by the RecBCD helicase/nuclease. The acquired integrated DNA was tracked through successive replication rounds and was found to occasionally split and segregate with different chromosomes, leading to the inheritance of different gene clusters within the cell lineage. The incidence of DNA splitting corresponds to about one crossover per cell generation.
接合作用使细菌能够获得抗生素抗性基因、新的毒力特性以及其他代谢途径。我们利用荧光蛋白融合体SeqA-YFP，在大肠杆菌的单细胞中实时观察到了这一过程。我们发现F菌毛在相当远的细胞间距离介导DNA转移。通过重组整合转移DNA的情况在高达96%的受体细胞中发生；在其余细胞中，转移的DNA被RecBCD解旋酶/核酸酶完全降解。通过连续的复制轮次追踪获得的整合DNA，发现其偶尔会分裂并与不同的染色体分离，导致细胞谱系内不同基因簇的遗传。DNA分裂的发生率约为每代细胞一次交叉。
