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.
Kim
S K
SK
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
Wang
J C
JC
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