Thiol-independent activity of a cholesterol-binding enterohemolysin produced by enteropathogenic Escherichia coli.
Enterohemolysin produced by Escherichia coli associated with infant diarrhea showed characteristics similar to those of thiol-activated hemolysins produced by Gram-positive bacteria, including inactivation by cholesterol, lytic activity towards eukaryotic cells and thermoinstability. However, enterohemolysin activity was not inactivated by oxidation or by SH group-blocking agents (1 mM HgCl2, 1 mM iodoacetic acid) and the hemolysin (100 microg/ml) was not lethal to mice, in contrast to the lethality of the thiol-activated hemolysin family to animals. Earlier reports showed that intravenous injection of partially purified streptolysin O preparations (0.2 microg) was rapidly lethal to mice. These results suggest that E. coli enterohemolysin is not a thiol-activated hemolysin, despite its ability to bind cholesterol, probably due to the absence of free thiol-group(s) that characterize the active form of the thiol-activated hemolysin molecule.
Figueirêdo
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PM
Departamento de Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brasil.
Catani
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CF
Yano
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D000818:Animals; D001427:Bacterial Toxins / Q000302:isolation & purification* / Q000633:toxicity; D002462:Cell Membrane; D002784:Cholesterol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000187:drug effects*; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins; D005057:Eukaryotic Cells / Q000187:drug effects*; D006460:Hemolysin Proteins / Q000302:isolation & purification* / Q000633:toxicity; D006461:Hemolysis; D008297:Male; D051379:Mice; D011485:Protein Binding
D001427:Bacterial Toxins; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C066219:enterohemolysin; D002784:Cholesterol