The expression of all virulence factors in Listeria monocytogenes characterized to date is controlled by the virulence regulator protein, PrfA. To identify further PrfA-regulated proteins, we examined supernatants of L. monocytogenes EGD harboring additional copies of the PrfA regulator for the presence of novel proteins. This led to the identification and biochemical purification of a hitherto...

Riboswitches are RNA elements acting in cis, controlling expression of their downstream genes through a metabolite-induced alteration of their secondary structure. Here, we demonstrate that two S-adenosylmethionine (SAM) riboswitches, SreA and SreB, can also function in trans and act as noncoding RNAs in Listeria monocytogenes. SreA and SreB control expression of the virulence regulator PrfA by...

Listeria monocytogenes has been extensively studied as a model facultative intracellular pathogen. While the roles of major virulence factors in host-pathogen interactions have been extensively characterized, recent work suggests that some of these factors can also contribute to environmental proliferation of this pathogen. In this study, we characterized two non-hemolytic transposon mutants of...

Listeriolysin O (LLO) and ActA are essential virulence determinants for Listeria monocytogenes pathogenesis. Transcription of actA and hly , encoding LLO, is regulated by PrfA and increases dramatically during intracellular infection. The 5 ¢ untranslated regions (5 ¢ UTRs) of actA and prfA have been shown to upregulate expression of their respective gene products. Here, we demonstrate that the...

PURPOSE The purpose of this study was to evaluate the amount of radiation exposure patients with small renal masses undergoing percutaneous cyroablation (PCA) or percutaneous radiofrequency ablation (PRFA) received during treatment and follow up. MATERIALS AND METHODS A retrospective review was conducted on all patients with small renal masses <4 cm treated with PCA or PRFA over a 7-year peri...

Majority of studies concerning the gene expression of Listeria monocytogenes have been done on pure culture states. Our objective was to study L.monocytogenes in a co-cultured state and to understand if microbes in their natural state of existence are different in their expression than that of the purely cultured lab grown forms. For a long period discussions have been on the expression of prfA...

Transcription of the Listeria monocytogenes positive regulatory factor A protein (PrfA) is initiated from either of two promoters immediately upstream of prfA (prfAp(1) and prfAp(2)) or from the upstream plcA promoter. We demonstrate that prfAp(2) is a functional sigma(B)-dependent promoter and that a sigB deletion mutation affects the virulence phenotype of L. monocytogenes. Thus, the alternat...

Following entry into the host cytosol, the bacterial pathogen Listeria monocytogenes dramatically increases the expression of several key virulence factors. The expression of actA, whose protein product is required for L. monocytogenes actin-based intracellular motility, is increased by more than 200-fold in cytosolic bacteria in comparison to broth-grown cultures. Two distinct promoter element...