title: 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.
authors.affiliation: Department of Physics, National University of Singapore, Singapore 117542, Singapore. johanmaarel@gmail.com.
authors.forename: Johan R C
authors.initials: JR
authors.lastname: van der Maarel
authors.affiliation: Department of Physics, National University of Singapore, Singapore 117542, Singapore. johanmaarel@gmail.com.
authors.forename: Durgarao
authors.initials: D
authors.lastname: Guttula
authors.affiliation: Laboratoire Léon Brillouin UMR 12 CEA, CNRS, Université Paris Saclay, CEA-Saclay, Gif sur Yvette Cedex 91191, France and Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Arluison
authors.affiliation: Heinrich-Heine University, Condensed Matter Physics Laboratory, Düsseldorf, 40225, Germany.
authors.forename: Stefan U
authors.initials: SU
authors.lastname: Egelhaaf
authors.affiliation: Institut Laue-Langevin, 38042 Grenoble, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Grillo
authors.affiliation: Institut Laue-Langevin, 38042 Grenoble, France and Keele University, Faculty of Natural Sciences, Staffordshire, ST5 5BG, UK.
authors.forename: V Trevor
authors.initials: VT
authors.lastname: Forsyth
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D023281:Genomics; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009698:Nucleoproteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; D009698:Nucleoproteins; D004247:DNA