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PMID:21097887

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Contents

Citation

Kahramanoglou, C, Seshasayee, AS, Prieto, AI, Ibberson, D, Schmidt, S, Zimmermann, J, Benes, V, Fraser, GM and Luscombe, NM (2011) Direct and indirect effects of H-NS and Fis on global gene expression control in Escherichia coli. Nucleic Acids Res. 39:2073-91

Abstract

Nucleoid-associated proteins (NAPs) are global regulators of gene expression in Escherichia coli, which affect DNA conformation by bending, wrapping and bridging the DNA. Two of these--H-NS and Fis--bind to specific DNA sequences and structures. Because of their importance to global gene expression, the binding of these NAPs to the DNA was previously investigated on a genome-wide scale using ChIP-chip. However, variation in their binding profiles across the growth phase and the genome-scale nature of their impact on gene expression remain poorly understood. Here, we present a genome-scale investigation of H-NS and Fis binding to the E. coli chromosome using chromatin immunoprecipitation combined with high-throughput sequencing (ChIP-seq). By performing our experiments under multiple time-points during growth in rich media, we show that the binding regions of the two proteins are mutually exclusive under our experimental conditions. H-NS binds to significantly longer tracts of DNA than Fis, consistent with the linear spread of H-NS binding from high- to surrounding lower-affinity sites; the length of binding regions is associated with the degree of transcriptional repression imposed by H-NS. For Fis, a majority of binding events do not lead to differential expression of the proximal gene; however, it has a significant indirect effect on gene expression partly through its effects on the expression of other transcription factors. We propose that direct transcriptional regulation by Fis is associated with the interaction of tandem arrays of Fis molecules to the DNA and possible DNA bending, particularly at operon-upstream regions. Our study serves as a proof-of-principle for the use of ChIP-seq for global DNA-binding proteins in bacteria, which should become significantly more economical and feasible with the development of multiplexing techniques.

Links

PubMed PMC3064808 Online version:10.1093/nar/gkq934

Keywords

Binding Sites; Chromosomes, Bacterial/metabolism; DNA, Bacterial/chemistry; DNA, Bacterial/metabolism; Escherichia coli/genetics; Escherichia coli/growth & development; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Factor For Inversion Stimulation Protein/genetics; Factor For Inversion Stimulation Protein/metabolism; Fimbriae Proteins/genetics; Fimbriae Proteins/metabolism; Gene Deletion; Gene Expression Regulation, Bacterial; Transcription, Genetic

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Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status

Data

Strain/Organism Assay Analyte Variable Conditions Notes Links

MG1655

ChIP-seq

Fis

early and mid exponential phase.

MG1655

ChIP-seq

H-NS

Early exponential, mid exponential, stationary, transition-to-stationary

MG1655

ChIP-seq

RNAP

Deletion Fis mid-exponential phase, deletion Hns mid-exponential phase, wildtype mid-exponential phase.

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