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PDBsum entry 2bgc
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Transcription
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PDB id
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2bgc
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References listed in PDB file
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Key reference
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Title
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The mutation g145s in prfa, A key virulence regulator of listeria monocytogenes, Increases DNA-Binding affinity by stabilizing the hth motif.
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Authors
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M.Eiting,
G.Hagelüken,
W.D.Schubert,
D.W.Heinz.
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Ref.
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Mol Microbiol, 2005,
56,
433-446.
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PubMed id
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Abstract
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Listeria monocytogenes, a Gram-positive, facultative intracellular human
pathogen, causes systemic infections with high mortality rate. The majority of
the known pathogenicity factors of L. monocytogenes is regulated by a single
transcription factor, PrfA. Hyperhaemolytic laboratory strains of L.
monocytogenes express the constitutively active mutant PrfA(G145S) inducing
virulence gene overexpression independent of environmental conditions. PrfA
belongs to the Crp/Fnr family of transcription factors generally activated by a
small effector, such as cAMP or O(2). We present the crystal structures of
wild-type PrfA, the first Gram-positive member of the Crp/Fnr family, and of the
constitutively active mutant PrfA(G145S). Cap (Crp) has previously been
described exclusively in the cAMP-induced (DNA-free and -bound) conformation. By
contrast, the PrfA structures present views both of the non-induced state and of
the mutationally activated form. The low DNA-binding affinity of wild-type PrfA
is supported both structurally (partly disordered helix-turn-helix motif,
overall geometry of the HTH alpha-helices deviates from Cap) and by surface
plasmon resonance analyses (K(D) = 0.9 microM). In PrfA(G145S) the HTH motifs
dramatically rearrange to adopt a conformation comparable to cAMP-induced Cap
and hence favourable for DNA binding, supported by a DNA-binding affinity of 50
nM. Finally, the hypothesis that wild-type PrfA, like other Crp/Fnr family
members, may require an as yet unidentified cofactor for activation is supported
by the presence of a distinct tunnel in PrfA, located at the interface of the
beta-barrel and the DNA-binding domain.
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