Enhanced Binding of Altered H-NS Protein to Flagellar Rotor Protein FliG Causes Increased Flagellar Rotational Speed and Hypermotility in Escherichia coli

• Published in: The Journal of biological chemistry Vol. 273; no. 37; pp. 24030 - 24036
• Main Authors: Donato, Gina M., Kawula, Thomas H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 11-09-1998; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Substitution; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Cross-Linking Reagents; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Escherichia coli; Escherichia coli - genetics; Escherichia coli - physiology; Escherichia coli - ultrastructure; Flagella - physiology; Flagella - ultrastructure; Fluorescence Polarization; Kinetics; Microscopy, Electron, Scanning; Models, Structural; Movement; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.273.37.24030

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 μm. 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.