A single substitution in the putative helix‐turn‐helix motif of the pleiotropic activator PrfA attenuates Listeria monocytogenes virulence
- 1 May 1996
- journal article
- Published by Wiley in Molecular Microbiology
- Vol. 20 (4) , 785-797
- https://doi.org/10.1111/j.1365-2958.1996.tb02517.x
Abstract
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.Keywords
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