Affiliation:
1. Skirball Institute and Department of Microbiology, New York University School of Medicine, New York, New York 10016,1 and
2. Center for Microbial Pathogenesis and Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 060302
Abstract
ABSTRACT
Shigella
spp. cause dysentery, a severe form of bloody diarrhea. Apoptosis, or programmed cell death, is induced during
Shigella
infections and has been proposed to be a key event in the pathogenesis of dysentery. Here, we describe a novel cytotoxic activity in the sterile-culture supernatants of
Shigella flexneri
. An identical activity was identified in purified
S. flexneri
endotoxin, defined here as a mixture of lipopolysaccharide (LPS) and endotoxin-associated proteins (EP). Separation of endotoxin into EP and LPS revealed the activity to partition exclusively to the EP fraction. Biochemical characterization of
S. flexneri
EP and culture supernatants, including enzymatic deactivation, reverse-phase high-pressure liquid chromatography analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and a Toll-like receptor-2 (TLR2) activation assay, indicates that the cytotoxic component is a mixture of bacterial lipoproteins (BLP). We show that biologically active BLP are liberated into culture supernatants of actively growing
S. flexneri
. In addition, our data indicate that BLP, and not LPS, are the component of endotoxin of gram-negative organisms responsible for activating TLR2. The activation of apoptosis by BLP shed from
S. flexneri
is discussed as a novel aspect of the interaction of bacteria with the host.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
38 articles.
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