title: Investigation of the self-association and hetero-association interactions of H-NS and StpA from Enterobacteria.
abstract: The nucleoid-associated protein H-NS and its paralogue StpA are global regulators of gene expression and form an integral part of the protein scaffold responsible for DNA condensation in Escherichia coli and Salmonella typhimurium. Although protein oligomerization is a requirement for this function, it is not entirely understood how this is accomplished. We address this by reporting on the self-association of H-NS and its hetero-association with StpA. We identify residues 1-77 of H-NS as being necessary and sufficient for high-order association. A multi-technique-based approach was used to measure the effects of salt concentration on the size distribution of H-NS and the thermal stability of H-NS and StpA dimers. The thermal stability of the StpA homodimer is significantly greater than that of H-NS(1-74). Investigation of the hetero-association of H-NS and StpA proteins suggested that the association of H-NS with StpA is more stable than the self-association of either H-NS or StpA with themselves. This provides a clear understanding of the method of oligomerization of these important proteins in effecting DNA condensation and reveals that the different associative properties of H-NS and StpA allow them to perform distinct, yet complementary roles in the bacterial nucleoid.
authors.affiliation: Department of Structural and Molecular Biology, University College London, London WC1E 6BT, UK.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Leonard
authors.forename: Shusuke
authors.initials: S
authors.lastname: Ono
authors.forename: Jayesh
authors.initials: J
authors.lastname: Gor
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Perkins
authors.forename: John E
authors.initials: JE
authors.lastname: Ladbury
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002850:Chromatography, Gel; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D055503:Protein Multimerization; D055550:Protein Stability; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; D018832:Molecular Chaperones; C090104:StpA protein, E coli