2BEO: Prfa, Transcriptional Regulator In Listeria Monocytogenes

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.
PDB ID: 2BEODownload
MMDB ID: 86794
PDB Deposition Date: 2004/11/26
Updated in MMDB: 2010/12
Experimental Method:
x-ray diffraction
Resolution: 2.7  Å
Source Organism:
Similar Structures:
Biological Unit for 2BEO: dimeric; determined by author and by software (PQS)
Molecular Components in 2BEO
Label Count Molecule
Proteins (2 molecules)
Listeriolysin Regulatory Protein(Gene symbol: prfA)
Molecule annotation
Chemicals (5 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB