lac Repressor Is an Antivirulence Factor of Salmonella enterica: Its Role in the Evolution of Virulence in Salmonella

Eswarappa, Sandeepa M and Karnam, Guruswamy and Nagarajan, Arvindhan G and Chakraborty, Sangeeta and Chakravortty, Dipshikha (2009) lac Repressor Is an Antivirulence Factor of Salmonella enterica: Its Role in the Evolution of Virulence in Salmonella. In: PLoS ONE, 4 (6).

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Abstract

The genus Salmonella includes many pathogens of great medical and veterinary importance. Bacteria belonging to this genus are very closely related to those belonging to the genus Escherichia. lacZYA operon and lacI are present in Escherichia coli, but not in Salmonella enterica. It has been proposed that Salmonella has lost lacZYA operon and lacI during evolution. In this study, we have investigated the physiological and evolutionary significance of the absence of lacI in Salmonella enterica. Using murine model of typhoid fever, we show that the expression of Lacl causes a remarkable reduction in the virulence of Salmonella enterica. Lacl also suppresses the ability of Salmonella enterica to proliferate inside murine macrophages. Microarray analysis revealed that Lacl interferes with the expression of virulence genes of Salmonella pathogenicity island 2. This effect was confirmed by RT-PCR and Western blot analysis. Interestingly, we found that SBG0326 of Salmonella bongori is homologous to lacI of Escherichia coli. Salmonella bongori is the only other species of the genus Salmonella and it lacks the virulence genes of Salmonella pathogenicity island 2. Overall, our results demonstrate that Lacl is an antivirulence factor of Salmonella enterica and suggest that absence of lacI has facilitated the acquisition of virulence genes of Salmonella pathogenicity island 2 in Salmonella enterica making it a successful systemic pathogen.

Item Type:	Journal Article
Publication:	PLoS ONE
Publisher:	Public Library Science
Additional Information:	© 2009 Eswarappa et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	19 Jan 2010 09:03
Last Modified:	19 Sep 2010 05:54
URI:	http://eprints.iisc.ac.in/id/eprint/25422

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