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Structure of the H-NS-DNA nucleoprotein complex.

Abstract

Nucleoid associated proteins (NAPs) play a key role in the compaction and expression of the prokaryotic genome. Here we report the organisation of a major NAP, the protein H-NS on a double stranded DNA fragment. For this purpose we have carried out a small angle neutron scattering study in conjunction with contrast variation to obtain the contributions to the scattering (structure factors) from DNA and H-NS. The H-NS structure factor agrees with a heterogeneous, two-state binding model with sections of the DNA duplex surrounded by protein and other sections having protein bound to the major groove. In the presence of magnesium chloride, we observed a structural rearrangement through a decrease in cross-sectional diameter of the nucleoprotein complex and an increase in fraction of major groove bound H-NS. The two observed binding modes and their modulation by magnesium ions provide a structural basis for H-NS-mediated genome organisation and expression regulation.

Acceptance Date Mar 9, 2016
Publication Date Mar 9, 2016
Journal Soft Matter
Print ISSN 1744-683X
Publisher Royal Society of Chemistry
Pages 3636 - 3642
DOI https://doi.org/10.1039/C5SM03076E
Publisher URL http://pubs.rsc.org/en/Content/ArticleLanding/2016/SM/C5SM03076E#!divAbstract

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