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Genes 2016, 7(12), 120;

The Virulence Regulator Rns Activates the Expression of CS14 Pili

Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
Author to whom correspondence should be addressed.
Academic Editor: Helen J. Wing
Received: 31 October 2016 / Revised: 28 November 2016 / Accepted: 30 November 2016 / Published: 8 December 2016
(This article belongs to the Special Issue Virulence Gene Regulation in Bacteria)
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Although many viral and bacterial pathogens cause diarrhea, enterotoxigenic E. coli (ETEC) is one of the most frequently encountered in impoverished regions where it is estimated to kill between 300,000 and 700,000 children and infants annually. Critical ETEC virulence factors include pili which mediate the attachment of the pathogen to receptors in the intestinal lumen. In this study we show that the ETEC virulence regulator Rns positively regulates the expression of CS14 pili. Three Rns binding sites were identified upstream of the CS14 pilus promoter centered at −34.5, −80.5, and −155.5 relative to the Rns-dependent transcription start site. Mutagenesis of the promoter proximal site significantly decreased expression from the CS14 promoter. In contrast, the contribution of Rns bound at the promoter distal site was negligible and largely masked by occupancy of the promoter proximal site. Unexpectedly, Rns bound at the site centered at −80.5 had a slight but statistically significant inhibitory effect upon the pilin promoter. Nevertheless, this weak inhibitory effect was not sufficient to overcome the substantial promoter activation from Rns bound to the promoter proximal site. Thus, CS14 pili belong to a group of pili that depend upon Rns for their expression. View Full-Text
Keywords: enterotoxigenic E. coli; ETEC; pili; Rns; activator enterotoxigenic E. coli; ETEC; pili; Rns; activator

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Bodero, M.D.R.; Munson, G.P. The Virulence Regulator Rns Activates the Expression of CS14 Pili. Genes 2016, 7, 120.

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