PMID:21890701

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Citation

Paul, K, Carlquist, WC and Blair, DF (2011) Adjusting the spokes of the flagellar motor with the DNA-binding protein H-NS. J. Bacteriol. 193:5914-22

Abstract

The H-NS protein of bacteria is a global regulator that stimulates transcription of flagellar genes and that also acts directly to modulate flagellar motor function. H-NS is known to bind FliG, a protein of the rotor that interacts with the stator and is directly involved in rotation of the motor. Here, we find that H-NS, well known for its ability to organize DNA, acts in the flagellar motor to organize protein subunits in the rotor. It binds to a middle domain of FliG that bridges the core parts of the rotor and parts nearer the edge that interact with the stator. In the absence of H-NS the organization of FliG subunits is disrupted, whereas overexpression of H-NS enhances FliG organization as monitored by targeted disulfide cross-linking, alters the disposition of a helix joining the middle and C-terminal domains of FliG, and enhances motor performance under conditions requiring a strengthened rotor-stator interface. The H-NS homolog StpA was also shown to bind FliG and to act similarly, though less effectively, in organizing FliG. The motility-enhancing effects of H-NS contrast with those of the recently characterized motility inhibitor YcgR. The present findings provide an integrated, structurally grounded framework for understanding the roughly opposing effects of these motility regulators.

Links

PubMed PMC3194902 Online version:10.1128/JB.05458-11

Keywords

Bacterial Proteins/metabolism; DNA-Binding Proteins/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli/physiology; Gene Expression; Gene Knockout Techniques; Locomotion; Macromolecular Substances/metabolism; Models, Biological; Models, Molecular; Molecular Motor Proteins/metabolism; Protein Binding; Protein Multimerization

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