title: Interaction between the bacterial nucleoid associated proteins Hha and H-NS involves a conformational change of Hha.
abstract: The H-NS family of proteins has been shown to participate in the regulation of a large number of genes in Gram-negative bacteria in response to environmental factors. In recent years, it has become apparent that proteins of the Hha family are essential elements for H-NS-regulated gene expression. Hha has been shown to bind H-NS, although the details for this interaction are still unknown. In the present paper, we report fluorescence anisotropy and NMR studies of the interaction between Hha and H-NS64, a truncated form of H-NS containing only its N-terminal dimerization domain. We demonstrate the initial formation of a complex between one Hha and two H-NS64 monomers in 150 mM NaCl. This complex seems to act as a nucleation unit for higher-molecular-mass complexes. NMR studies suggest that Hha is in equilibrium between two different conformations, one of which is stabilized by binding to H-NS64. A similar exchange is also observed for Hha in the absence of H-NS when temperature is increased to 37 degrees C, suggesting a key role for intrinsic conformational changes of Hha in modulating its interaction with H-NS.
authors.affiliation: Laboratory of Biomolecular NMR, Parc Científic de Barcelona, Josep Samitier, 1-5, 08028-Barcelona, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: García
authors.forename: Tiago N
authors.initials: TN
authors.lastname: Cordeiro
authors.forename: José M
authors.initials: JM
authors.lastname: Nieto
authors.forename: Ignacio
authors.initials: I
authors.lastname: Pons
authors.forename: Antonio
authors.initials: A
authors.lastname: Juárez
authors.forename: Miquel
authors.initials: M
authors.lastname: Pons
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D019281:Dimerization; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D005454:Fluorescence Polarization; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; C079209:hha protein, E coli
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