HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Velge, P. Articles by Cossart, P. Search for Related Content PubMed PubMed Citation Articles by Velge, P. Articles by Cossart, P. Agricola Articles by Velge, P. Articles by Cossart, P.

A naturally occurring mutation K220T in the pleiotropic activator PrfA of Listeria monocytogenes results in a loss of virulence due to decreasing DNA-binding affinity

¹ Institut National de la Recherche Agronomique, UR1282 Infectiologie animale et santé publique, 37380 Nouzilly, France
² Lehrstuhl für Mikrobiologie, Theodor-Boveri-Institut für Biowissenschaften der Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
³ Institut Pasteur, Unité des Interactions Bactéries-Cellules, 28 rue du Docteur Roux, 75015 Paris, France
⁴ Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, USA

Correspondence
P. Velge
Philippe.velge{at}tours.inra.fr

The sequencing of prfA, encoding the transcriptional regulator of virulence genes, in 26 low-virulence field Listeria monocytogenes strains showed that eight strains exhibited the same single amino-acid substitution: PrfAK220T. These strains exhibited no expression of PrfA-regulated proteins and thus no virulence. This substitution inactivated PrfA, since expression of the PrfAK220T mutant gene in an EGDprfA strain did not restore the haemolytic and phosphatidylcholine phospholipase C activities, in contrast to the wild-type prfA gene. The substitution of the lysine at position 220 occurred in the helix H. However, the data showed that the PrfAK220T protein is dimerized just as well as its wild-type counterpart, but does not bind to PrfA-boxes. PrfAK220T did not form a PrfA–DNA complex in electrophoretic mobility shift assays, but low concentrations of CI complexes (PrfAK220T–RNA polymerase–DNA complex) were formed by adding RNA polymerase, suggesting that PrfA interacted with RNA polymerase in solution in the absence of DNA. Formation of some transcriptionally active complexes was confirmed by in vitro runoff transcription assays and quantitative RT-PCR. Crystallographic analyses described the structure of native PrfA and highlighted the key role of allosteric changes in the activity of PrfA and especially the role of the Lys220 in the conformation of the helix–turn–helix (HTH) motif.

This article has been cited by other articles:

				B. Joseph, S. Mertins, R. Stoll, J. Schar, K. R. Umesha, Q. Luo, S. Muller-Altrock, and W. Goebel Glycerol Metabolism and PrfA Activity in Listeria monocytogenes J. Bacteriol., August 1, 2008; 190(15): 5412 - 5430. [Abstract] [Full Text] [PDF]

				C. D. Doern, R. C. Holder, and S. D. Reid Point mutations within the streptococcal regulator of virulence (Srv) alter protein-DNA interactions and Srv function Microbiology, July 1, 2008; 154(7): 1998 - 2007. [Abstract] [Full Text] [PDF]

				S. Temoin, S. M. Roche, O. Grepinet, Y. Fardini, and P. Velge Multiple point mutations in virulence genes explain the low virulence of Listeria monocytogenes field strains Microbiology, March 1, 2008; 154(3): 939 - 948. [Abstract] [Full Text] [PDF]