Bacterial biofilms are complex communities of cells that are attached to a surface
by an extracellular matrix. Biofilms are an increasing environmental and healthcare
issue, causing problems ranging from the biofouling of ocean-going vessels, to dental
plaque, infections of the urinary tract, and contamination of medical instruments
such as catheters. A complete understanding of biofilm formation therefore requires
knowledge of the regulatory pathways underpinning its formation so that effective
intervention strategies can be determined. The master regulator that determines whether
the Gram-positive model organism
Bacillus subtilis switches from a free-living, planktonic lifestyle to form a biofilm is called SinR.
The activity of SinR, a transcriptional regulator, is controlled by its antagonists,
SinI, SlrA, and SlrR. The interaction of these four proteins forms a switch, which
determines whether or not SinR can inhibit biofilm formation by its repression of
a number of extracellular matrix-associated operons. To determine the thermodynamic
and kinetic parameters governing the protein-protein and protein-DNA interactions
at the heart of this epigenetic switch, we have analyzed the protein-protein and protein-DNA
interactions by isothermal titration calorimetry and surface plasmon resonance. We
also present the crystal structure of SinR in complex with DNA, revealing the molecular
basis of base-specific DNA recognition by SinR and suggesting that the most effective
means of transcriptional control occurs by the looping of promoter DNA. The structural
analysis also enables predictions about how SinR activity is controlled by its interaction
with its antagonists.
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Article Info
Publication History
Received in revised form:
February 21,
2013
Received:
January 22,
2013
Footnotes
The atomic coordinates and structure factors (code 3zkc) have been deposited in the Protein Data Bank (http://wwpdb.org/).
Identification
Copyright
© 2013 ASBMB. Currently published by Elsevier Inc; originally published by American Society for Biochemistry and Molecular Biology.
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