Gene silencing via protein-mediated subcellular localization of DNA.
We previously reported that overexpression of SopB, an Escherichia coli F plasmid-encoded partition protein, led to silencing of genes linked to, but well-separated from, a cluster of SopB-binding sites termed sopC. We show here that in this SopB-mediated repression of sopC-linked genes, all but the N-terminal 82 amino acids of SopB can be replaced by the DNA-binding domain of a sequence-specific DNA-binding protein, provided that the sopC locus is also replaced by the recognition sequence of the DNA-binding domain. These results, together with our previous finding that the N-terminal fragment of SopB is responsible for its polar localization in cells, suggest a mechanism of gene silencing: patches of closely packed DNA-binding domains are formed if a sequence-specific DNA-binding protein is localized to specific cellular sites; such a patch can capture a DNA carrying the recognition site of the DNA-binding domain and sequestrate genes adjacent to the recognition site through nonspecific binding of DNA. The generalization of this model to gene silencing in eukaryotes is discussed.
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
S K
SK
Kim
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JC
Wang
D001426:Bacterial Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005656:Fungal Proteins / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial; D017930:Genes, Reporter; D010446:Peptide Fragments / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics; D001616:beta-Galactosidase / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C060972:SopB protein, Bacteria; C489223:SopB protein, E coli; D014157:Transcription Factors; D001616:beta-Galactosidase