Illegitimate recombination induced by overproduction of DnaB helicase in Escherichia coli.
Illegitimate recombination that usually takes place at a low frequency is greatly enhanced by treatment with DNA-damaging agents. It is thought that DNA double-strand breaks induced by this DNA damage are important for initiation of illegitimate recombination. Here we show that illegitimate recombination is enhanced by overexpression of the DnaB protein in Escherichia coli. The recombination enhanced by DnaB overexpression occurred between short regions of homology. We propose a model for the initiation of illegitimate recombination in which DnaB overexpression may excessively unwind DNA at replication forks and induce double-strand breaks, resulting in illegitimate recombination. The defect in RecQ has a synergistic effect on the increased illegitimate recombination in cells containing the overproduced DnaB protein, implying that DnaB works in the same pathway as RecQ does but that they work at different steps.
Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan.
T
T
Yamashita
K
K
Hanada
M
M
Iwasaki
H
H
Yamaguchi
H
H
Ikeda
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism*; D053488:DnaB Helicases; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005838:Genotype; D008969:Molecular Sequence Data; D010641:Phenotype; D011995:Recombination, Genetic; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid
D001426:Bacterial Proteins; D004265:DNA Helicases; D053488:DnaB Helicases