Escherichia coli cell cycle control genes affect chromosome superhelicity.
We have used ethidium bromide titration for direct measurement of the changes in the negative supercoiling of Escherichia coli chromosome caused by mutations inactivating the cell cycle functions mukB and seqA. The amounts of the intercalative agent required to relax the supercoiled chromosome in mukB and seqA mutants were lower and higher, respectively, than for the wild-type parent, confirming that these cell cycle genes modulate the topology of the E. coli chromosome. Plasmid superhelicity measured in these mutant strains showed similar effects albeit of reduced magnitude. As the effects of mukB and seqA mutations were not restricted to the chromosome alone, MukB and SeqA proteins possibly interact with factors involved in the maintenance of intracellular DNA topology. To our knowledge, this is the first direct demonstration of the influence of mukB and seqA genes on the superhelicity of the E. coli chromosome.
Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Sweden.
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Weitao
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Nordström
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Dasgupta
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D002453:Cell Cycle / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D002738:Chloroquine / Q000494:pharmacology; D002868:Chromosomal Proteins, Non-Histone; D002875:Chromosomes / Q000648:ultrastructure*; D004278:DNA, Superhelical / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D015246:Deoxyribonuclease EcoRI / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004587:Electrophoresis, Agar Gel; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D004996:Ethidium / Q000494:pharmacology; D007364:Intercalating Agents / Q000494:pharmacology; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D014157:Transcription Factors
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002868:Chromosomal Proteins, Non-Histone; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D007364:Intercalating Agents; C067035:MukB protein, E coli; C089746:SeqA protein, E coli; D014157:Transcription Factors; C489340:recF protein, E coli; D013395:Sucrose; D002738:Chloroquine; C066218:recF protein, Bacteria; D015246:Deoxyribonuclease EcoRI; D004996:Ethidium