Abstract
Bacterial chromosomes are confined in submicrometer-sized nucleoids. Chromosome organization is facilitated by nucleoid-associated proteins (NAPs), but the mechanisms of action remain elusive. In this work, we used super-resolution fluorescence microscopy, in combination with a chromosome-conformation capture assay, to study the distributions of major NAPs in live Escherichia coli cells. Four NAPs--HU, Fis, IHF, and StpA--were largely scattered throughout the nucleoid. In contrast, H-NS, a global transcriptional silencer, formed two compact clusters per chromosome, driven by oligomerization of DNA-bound H-NS through interactions mediated by the amino-terminal domain of the protein. H-NS sequestered the regulated operons into these clusters and juxtaposed numerous DNA segments broadly distributed throughout the chromosome. Deleting H-NS led to substantial chromosome reorganization. These observations demonstrate that H-NS plays a key role in global chromosome organization in bacteria.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Binding Sites
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Cell Division
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Chromosomes, Bacterial / metabolism*
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Chromosomes, Bacterial / ultrastructure*
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DNA, Bacterial / chemistry
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DNA, Bacterial / metabolism*
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DNA-Binding Proteins / metabolism
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Escherichia coli K12 / genetics
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Escherichia coli K12 / metabolism
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Escherichia coli K12 / ultrastructure*
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Escherichia coli Proteins / chemistry
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Escherichia coli Proteins / genetics
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Escherichia coli Proteins / metabolism*
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Factor For Inversion Stimulation Protein / metabolism
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Fimbriae Proteins / chemistry
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Fimbriae Proteins / genetics
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Fimbriae Proteins / metabolism*
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Gene Expression Regulation, Bacterial
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Genetic Loci
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Genome, Bacterial
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Integration Host Factors / metabolism
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Molecular Chaperones / metabolism
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Nucleic Acid Conformation
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Operon
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Protein Multimerization
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Protein Structure, Tertiary
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Recombinant Fusion Proteins / metabolism
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Repressor Proteins / chemistry
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Repressor Proteins / genetics
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Repressor Proteins / metabolism*
Substances
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DNA, Bacterial
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DNA-Binding Proteins
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Escherichia coli Proteins
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Factor For Inversion Stimulation Protein
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FimG protein, E coli
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Fis protein, E coli
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Integration Host Factors
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Molecular Chaperones
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Recombinant Fusion Proteins
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Repressor Proteins
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StpA protein, E coli
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hns protein, E coli
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integration host factor, E coli
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Fimbriae Proteins