title: Enhanced binding of altered H-NS protein to flagellar rotor protein FliG causes increased flagellar rotational speed and hypermotility in Escherichia coli.
abstract: H-NS is an Escherichia coli nucleoid protein known only to function as a modulator of gene expression. In this study, we found that specific single amino acid substitutions in H-NS caused an approximately 50% increase in flagellum rotational speed. In fluorescence anisotropy and chemical cross-linking assays, H-NS interacted with the flagellar torque-generating rotor protein FliG to form a complex with a Kd of 2.15 microM. Furthermore, one of the altered H-NS proteins that exhibited high speed flagellum rotation bound FliG 50% tighter than wild-type H-NS. These results demonstrate the first non-regulatory role for H-NS and provide a direct correlation between H-NS-FliG binding affinities, flagellar rotation, and motor torque generation.
authors.affiliation: Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7290, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Donato
authors.forename: T H
authors.initials: TH
authors.lastname: Kawula
mesh_terms: D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D005407:Flagella / Q000502:physiology* / Q000648:ultrastructure; D005454:Fluorescence Polarization; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D008961:Models, Structural; D009068:Movement; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; C075660:Flig protein, Bacteria; C031908:H-NS protein, bacteria; D011994:Recombinant Proteins