Browsing by Subject "Vibrio cholerae"

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    Amino acid divergence in the ligand-binding pocket of Vibrio LuxR/HapR proteins determines the efficacy of thiophenesulfonamide inhibitors
    (Wiley, 2021) Newman, Jane D.; Chopra, Jay; Shah, Priyanka; Shi, Eda; McFadden, Molly E.; Horness, Rachel E.; Brown, Laura C.; van Kessel, Julia C.; Medicine, School of Medicine
    The quorum sensing signaling systems in Vibrio bacteria converge to control levels of the master transcription factors LuxR/HapR, a family of highly conserved proteins that regulate gene expression for bacterial behaviors. A compound library screen identified 2-thiophenesulfonamide compounds that specifically inhibit Vibrio campbellii LuxR but do not affect cell growth. We synthesized a panel of 50 thiophenesulfonamide compounds to examine the structure-activity relationship effects on Vibrio quorum sensing. The most potent molecule identified, PTSP (3-phenyl-1-(thiophen-2-ylsulfonyl)-1H-pyrazole), inhibits quorum sensing in multiple strains of Vibrio vulnificus, Vibrio parahaemolyticus, and V. campbellii at nanomolar concentrations. However, thiophenesulfonamide inhibition efficacy varies significantly among Vibrio species: PTSP is most inhibitory against V. vulnificus SmcR, but V. cholerae HapR is completely resistant to all thiophenesulfonamides tested. Reverse genetics experiments show that PTSP efficacy is dictated by amino acid sequence in the putative ligand binding pocket: F75Y and C170F SmcR substitutions are each sufficient to eliminate PTSP inhibition. Further, in silico modeling distinguished the most potent thiophenesulfonamides from less effective derivatives. Our results revealed the previously unknown differences in LuxR/HapR proteins that control quorum sensing in Vibrio species and underscore the potential for developing thiophenesulfonamides as specific quorum sensing-directed treatments for Vibrio infections.
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    Leucine-Rich, Potent Anti-Bacterial Protein against Vibrio cholerae, Staphylococcus aureus from Solanum trilobatum Leaves
    (MDPI, 2022-02-09) Radhakrishnan, Manohar; Palayam, Malathy; Altemimi, Ammar B.; Karthik, Lakshminarayanan; Krishnasam, Gunasekaran; Cacciola, Francesco; Govindan, Lakshmanan; Chemistry and Chemical Biology, School of Science
    A 24 kDa leucine-rich protein from ion exchange fractions of Solanum trilobatum, which has anti-bacterial activity against both the Gram-negative Vibrio cholerae and Gram-positive Staphylococcus aureus bacteria has been purified. In this study, mass spectrometry analysis identified the leucine richness and found a luminal binding protein (LBP). Circular dichroism suggests that the protein was predominantly composed of α- helical contents of its secondary structure. Scanning electron microscopy visualized the characteristics and morphological and structural changes in LBP-treated bacterium. Further in vitro studies confirmed that mannose-, trehalose- and raffinose-treated LBP completely inhibited the hemagglutination ability towards rat red blood cells. Altogether, these studies suggest that LBP could bind to sugar moieties which are abundantly distributed on bacterial surface which are essential for maintaining the structural integrity of bacteria. Considering that Solanum triolbatum is a well-known medicinal and edible plant, in order to shed light on its ancient usage in this work, an efficient anti-microbial protein was isolated, characterized and its in vitro functional study against human pathogenic bacteria was evaluated.