The Experts below are selected from a list of 3459 Experts worldwide ranked by ideXlab platform
James D Jamieson - One of the best experts on this subject based on the ideXlab platform.
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amylase release from Streptolysin o permeabilized fetal pancreatic acini
American Journal of Physiology-gastrointestinal and Liver Physiology, 1992Co-Authors: Daniel J Cher, Philip J Padfield, James D JamiesonAbstract:Developmental regulation of Ca(2+)-dependent protein discharge was investigated in fetal and neonatal rat pancreatic acini permeabilized with Streptolysin O. When incubated at 37 degrees C in a Ca(...
Manfred Gratzl - One of the best experts on this subject based on the ideXlab platform.
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amylase release from Streptolysin o permeabilized pancreatic acinar cells effects of ca2 guanosine 5 gamma thio triphosphate cyclic amp tetanus toxin and botulinum a toxin
Biochemical Journal, 1992Co-Authors: B Stecher, U Weller, Gudrun Ahnerthilger, T P Kemmer, Manfred GratzlAbstract:The molecular requirements for amylase release and the intracellular effects of botulinum A toxin and tetanus toxin on amylase release were investigated using rat pancreatic acinar cells permeabilized with Streptolysin O. Micromolar concentrations of free Ca2+ evoked amylase release from these cells. Maximal release was observed in the presence of 30 microM free Ca2+. Ca(2+)-stimulated, but not basal, amylase release was enhanced by guanosine 5'-[gamma-thio]triphosphate (GTP[S]) (3-4 fold) or cyclic AMP (1.5-2 fold). Neither the two-chain forms of botulinum A toxin and tetanus toxin, under reducing conditions, nor the light chains of tetanus toxin, inhibited amylase release triggered by Ca2+, or combinations of Ca2+ + GTP[S] or Ca2+ + cAMP. The lack of inhibition was not due to inactivation of botulinum A toxin or tetanus toxin by pancreatic acinar cell proteolytic enzymes, as toxins previously incubated with permeabilized pancreatic acinar cells inhibited Ca(2+)-stimulated [3H]noradrenaline release from Streptolysin O-permeabilized adrenal chromaffin cells. These data imply that clostridial neurotoxins inhibit a Ca(2+)-dependent mechanism which promotes exocytosis in neural and endocrine cells, but not in exocrine cells.
Daniel Fologea - One of the best experts on this subject based on the ideXlab platform.
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liposomes prevent in vitro hemolysis induced by Streptolysin o and lysenin
Membranes, 2021Co-Authors: Marcelo Ayllon, Gamid Abatchev, Andrew Bogard, Rosey Whiting, Sarah E Hobdey, Daniel FologeaAbstract:The need for alternatives to antibiotics in the fight against infectious diseases has inspired scientists to focus on antivirulence factors instead of the microorganisms themselves. In this respect, prior work indicates that tiny, enclosed bilayer lipid membranes (liposomes) have the potential to compete with cellular targets for toxin binding, hence preventing their biological attack and aiding with their clearance. The effectiveness of liposomes as decoy targets depends on their availability in the host and how rapidly they are cleared from the circulation. Although liposome PEGylation may improve their circulation time, little is known about how such a modification influences their interactions with antivirulence factors. To fill this gap in knowledge, we investigated regular and long-circulating liposomes for their ability to prevent in vitro red blood cell hemolysis induced by two potent lytic toxins, lysenin and Streptolysin O. Our explorations indicate that both regular and long-circulating liposomes are capable of similarly preventing lysis induced by Streptolysin O. In contrast, PEGylation reduced the effectiveness against lysenin-induced hemolysis and altered binding dynamics. These results suggest that toxin removal by long-circulating liposomes is feasible, yet dependent on the particular virulence factor under scrutiny.
Daniel J Cher - One of the best experts on this subject based on the ideXlab platform.
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amylase release from Streptolysin o permeabilized fetal pancreatic acini
American Journal of Physiology-gastrointestinal and Liver Physiology, 1992Co-Authors: Daniel J Cher, Philip J Padfield, James D JamiesonAbstract:Developmental regulation of Ca(2+)-dependent protein discharge was investigated in fetal and neonatal rat pancreatic acini permeabilized with Streptolysin O. When incubated at 37 degrees C in a Ca(...
Douglas A Mitchell - One of the best experts on this subject based on the ideXlab platform.
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TOMM D ML Tree
2016Co-Authors: Evelyn M Molloy, Tucker Maxson, Courtney L Cox, Nicole A Ethridge, Gabriele Margos, Volker Fingerle, Sherwood R. Casajens, Douglas A MitchellAbstract:A maximum-likelihood tree of a representative sample of TOMMs based on the D protein from each cluster. Clades are color-coded based on the predicted class of TOMM natural product. NHLP, nitrile hydratase leader peptide; NHLP-Burk, NHLP from Burkholderia; PZN, plantazolicin; Balh, uncharacterized TOMM from Bacillus sp. Al Hakam; McB, microcin B from Gammaproteobacteria. SLS, Streptolysin S; Bor TOMM, putative SLS-like cytolysin from Bbsl
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identification of the minimal cytolytic unit for Streptolysin s and an expansion of the toxin family
BMC Microbiology, 2015Co-Authors: Evelyn M Molloy, Tucker Maxson, Sherwood R Casjens, Nicole A Ethridge, Gabriele Margos, Volker Fingerle, Douglas A MitchellAbstract:Background Streptolysin S (SLS) is a cytolytic virulence factor produced by the human pathogen Streptococcus pyogenes and other Streptococcus species. Related “SLS-like” toxins have been characterized in select strains of Clostridium and Listeria, with homologous clusters bioinformatically identified in a variety of other species. SLS is a member of the thiazole/oxazole-modified microcin (TOMM) family of natural products. The structure of SLS has yet to be deciphered and many questions remain regarding its structure-activity relationships.
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hiv protease inhibitors block Streptolysin s production
ACS Chemical Biology, 2015Co-Authors: Tucker Maxson, Andrew L Markley, Shaun W Lee, Evelyn M Molloy, Caitlin D Deane, Courtney L Cox, Douglas A MitchellAbstract:Streptolysin S (SLS) is a post-translationally modified peptide cytolysin that is produced by the human pathogen Streptococcus pyogenes. SLS belongs to a large family of azole-containing natural products that are biosynthesized via an evolutionarily conserved pathway. SLS is an important virulence factor during S. pyogenes infections, but despite an extensive history of study, further investigations are needed to clarify several steps of its biosynthesis. To this end, chemical inhibitors of SLS biosynthesis would be valuable tools to interrogate the various maturation steps of both SLS and biosynthetically related natural products. Such chemical inhibitors could also potentially serve as antivirulence therapeutics, which in theory may alleviate the spread of antibiotic resistance. In this work, we demonstrate that FDA-approved HIV protease inhibitors, especially nelfinavir, block a key proteolytic processing step during SLS production. This inhibition was demonstrated in live S. pyogenes cells and through...
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Streptolysin s like virulence factors the continuing saga
Nature Reviews Microbiology, 2011Co-Authors: Evelyn M Molloy, Paul D Cotter, Colin Hill, Douglas A Mitchell, Paul R RossAbstract:Streptolysin S (SLS) is a potent cytolytic toxin and virulence factor that is produced by nearly all Streptococcus pyogenes strains. Despite a 100-year history of research on this toxin, it has only recently been established that SLS is just one of an extended family of post-translationally modified virulence factors (the SLS-like peptides) that are produced by some streptococci and other Gram-positive pathogens, such as Listeria monocytogenes and Clostridium botulinum. In this Review, we describe the identification, genetics, biochemistry and various functions of SLS. We also discuss the shared features of the virulence-associated SLS-like peptides, as well as their place within the rapidly expanding family of thiazole/oxazole-modified microcins (TOMMs).
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clostridiolysin s a post translationally modified biotoxin from clostridium botulinum
Journal of Biological Chemistry, 2010Co-Authors: David Gonzalez, Victor Nizet, Andrew L Markley, Shaun W Lee, Douglas A Mitchell, Jack E Dixon, Mary E Hensler, Samira Dahesh, Nuno Bandeira, Pieter C DorresteinAbstract:Through elaboration of its botulinum toxins, Clostridium botulinum produces clinical syndromes of infant botulism, wound botulism, and other invasive infections. Using comparative genomic analysis, an orphan nine-gene cluster was identified in C. botulinum and the related foodborne pathogen Clostridium sporogenes that resembled the biosynthetic machinery for Streptolysin S, a key virulence factor from group A Streptococcus responsible for its hallmark β-hemolytic phenotype. Genetic complementation, in vitro reconstitution, mass spectral analysis, and plasmid intergrational mutagenesis demonstrate that the Streptolysin S-like gene cluster from Clostridium sp. is responsible for the biogenesis of a novel post-translationally modified hemolytic toxin, clostridiolysin S.
