Dynamic events of sister chromosomes in the cell cycle of Escherichia coli.
Various events involving partitioning of sister chromosomes were precisely analyzed in asynchronously growing Escherichia coli cells in various conditions. To examine the cohesion between sister chromosomes, we analyzed living cells growing under various conditions for the number of the replication origin (oriC) copies by flow cytometry and the foci of oriC by fluorescence microscopy. The average number of the oriC foci per cell was significantly smaller than the number of oriC copies per cell with few exceptions, suggesting cohesion of oriC sister copies. Cohesion phenomenon of oriC sister copies was also observed in a mukB null mutant cells under some growth conditions. Sister copies of the terminal region (ter) were also found to be cohesive. Immunofluorescence microscopy for nascent DNA pulse-labeled with 5-bromo-2'-deoxyuridine (BrdU) indicated that paired replication forks acting on bidirectional replication were able to migrate toward opposite directions during ongoing replication in poor medium; however, some of them were closely associated in rich media. Analysis of the foci of MukB-GFP indicates that the number of MukB foci was always larger than the number of replication forks. The number of MukB-GFP foci increased together with cell length. The sequence of these chromosomal events in the growing cells has been depicted.
Adachi
Shun
S
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
Fukushima
Toru
T
Hiraga
Sota
S
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology* / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005434:Flow Cytometry; D018628:Gene Dosage; D005798:Genes, Bacterial; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D008856:Microscopy, Fluorescence; D009154:Mutation; D051738:Origin Recognition Complex / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D002868:Chromosomal Proteins, Non-Histone; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C076835:FtsZ84 protein, E coli; C067035:MukB protein, E coli; C114650:OriC chromosomal replication origin; D051738:Origin Recognition Complex; D011993:Recombinant Fusion Proteins; C089746:SeqA protein, E coli; D049452:Green Fluorescent Proteins; D001973:Bromodeoxyuridine