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PrfA-G145S, a constitutive active mutant of the Transcriptional Regulator In L.monocytogenes
Structural highlights
FunctionPRFA_LISMO Positively regulates expression of listeriolysin, of 1-phosphadidylinositol phosphodiesterase (PI-PLC) and other virulence factors. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedListeria 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. The mutation G145S in PrfA, a key virulence regulator of Listeria monocytogenes, increases DNA-binding affinity by stabilizing the HTH motif.,Eiting M, Hageluken G, Schubert WD, Heinz DW Mol Microbiol. 2005 Apr;56(2):433-46. PMID:15813735[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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