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A single substitution in the putative helix‐turn‐helix motif of the pleiotropic activator PrfA attenuates Listeria monocytogenes virulence
Author(s) -
Sheehan Brian,
Klarsfeld André,
Ebright Richard,
Cossart Pascale
Publication year - 1996
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1996.tb02517.x
Subject(s) - virulence , biology , listeria monocytogenes , gene , dna , genetics , activator (genetics) , sequence motif , bacteria
Summary Prf A, the regulator of virulence‐gene expression in the pathogenic bacterium Listeria monocytogenes , displays sequence similarity to members of the CAP‐FNR family of transcriptional regulators. To test the functional significance of this similarity, we constructed and analysed substitutions of two amino acids of Prf A predicted to contact DNA, i.e. Ser‐184 and Ser‐183. Substitution of Ser‐184 by Ala reduced DNA binding and virulence‐gene activation, and attenuated the virulence in a mouse model of infection. In contrast, substitution of Ser‐183 by Ala had the opposite effect in these functional assays. A 17bp DNA sequence, which includes a putative PrfA site, was shown to be sufficient for target‐site recognition by PrfA and PrfA‐S183A. Our results strongly support the hypothesis that PrfA is a structural and functional homologue of CAP. In addition, they establish a clear correlation between DNA binding by PrfA, virulence‐gene activation, and virulence.