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PDBsum entry 3bxe
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Gene regulation
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PDB id
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3bxe
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References listed in PDB file
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Key reference
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Title
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Crystal structures of the effector-Binding domain of repressor central glycolytic gene regulator from bacillus subtilis reveal ligand-Induced structural changes upon binding of several glycolytic intermediates.
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Authors
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P.Rezácová,
M.Kozísek,
S.F.Moy,
I.Sieglová,
A.Joachimiak,
M.Machius,
Z.Otwinowski.
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Ref.
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Mol Microbiol, 2008,
69,
895-910.
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PubMed id
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Abstract
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Expression of genes in the gapA operon encoding five enzymes for triose
phosphate interconversion in Bacillus subtilis is negatively regulated by the
Central glycolytic genes Regulator (CggR). CggR belongs to the large SorC/DeoR
family of prokaryotic transcriptional regulators, characterized by an N-terminal
DNA-binding domain and a large C-terminal effector-binding domain. When no
glucose is present in growth media, CggR binds to its target DNA sequence and
blocks the transcription of genes in the gapA operon. In the presence of
glucose, binding of the known effector molecule fructose-1,6-bisphosphate
abolishes this interaction. We have identified dihydroxyacetone phosphate,
glucose-6-phosphate and fructose-6-phosphate as additional CggR ligands that can
bind to the effector-binding site. Crystal structures of C-CggR, the C-terminal
effector-binding domain of CggR, both unliganded as well as in complex with the
four ligands at resolutions between 1.65 and 1.80 A reveal unique
ligand-specific structural changes in the binding site that affect the dimer
interface. Binding affinities of these ligands were determined by isothermal
titration calorimetry. Chemical cross-linking shows that CggR oligomerization is
mediated through its effector-binding domain, and that binding of the different
ligands differentially affects the distribution of oligomers. Electrophoretic
mobility shift assays (EMSAs) confirmed a destabilizing effect of
fructose-1,6-bisphosphate on the CggR/DNA complex, and also showed similar
effects for dihydroxyacetone phosphate. Our results suggest that CggR stability
and function may be modulated by various effectors in a complex fashion.
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