Amino acid sequence homology between cholera toxin and Escherichia coli heat-labile toxin

Dallas, Walter S.; Falkow, Stanley

doi:10.1038/288499a0

Cited by 308 publications

(154 citation statements)

References 25 publications

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“…While a signal sequence is required for periplasmic secretion there is no evidence that such sequences are required for secretion across the outer cell membrane. Enterotoxins contain signal sequences which are cleaved during secretion (Dallas & Falkow, 1980), while haemolysin is released extracellularly without cleavage of the signal peptide. The mechanism by which 1986 8 proteins cross the outer membrane is unclear but appears to be more complex than for periplasmic secretion.…”

Section: Direct Expressionmentioning

confidence: 99%

The purification of eukaryotic polypeptides synthesized in Escherichia coli

Marston¹

1986

Biochemical Journal

859

379

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Section: Direct Expressionmentioning

confidence: 99%

The purification of eukaryotic polypeptides synthesized in Escherichia coli

Marston¹

1986

Biochemical Journal

859

379

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“…Secretion of mutarotase from E. coli WH1372 into the culture medium Specific excretion of proteins into the culture medium is a very unusual event in E. coli. It has only been described so far for hemolysin (10) (11,12). Therefore, the excretion of mutarotase from E. coli WH1372 was characterized.…”

Section: Analysis Of the Leader Peptidementioning

confidence: 99%

“…

(11,12). Non-specific leakage through the outer membrane has been described for the expression of penicillinase from alkalo-

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mentioning

confidence: 99%

Acinetobacter calcoaceticusencoded mutarotase: nucleotide sequence analysis of the gene and characterization of its secretion inEscherichia coli

Gatz

Hillen

1986

Nucl Acids Res

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“…These heteromeric toxins consist of a catalytic A subunit (LTA) and a pentamer of receptor-binding B subunits (LTB) (8,9). In addition to structural homology, LT shares 80% sequence homology with the Vibrio cholerae toxin CT (10,11). The ring-shaped B pentamer of both LT and CT mediates binding to the host epithelial receptor G M1 (12)(13)(14).…”

mentioning

confidence: 99%

Bacterial Surface Association of Heat-labile Enterotoxin through Lipopolysaccharide after Secretion via the General Secretory Pathway

Horstman

Kuehn

2002

Journal of Biological Chemistry

137

164

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Heat-labile enterotoxin (LT) is an important virulence factor expressed by enterotoxigenic Escherichia coli.The route of LT secretion through the outer membrane and the cellular and extracellular localization of secreted LT were examined. Using a fluorescently labeled receptor, LT was found to be specifically secreted onto the surface of wild type enterotoxigenic Escherichia coli. The main terminal branch of the general secretory pathway (GSP) was necessary and sufficient to localize LT to the bacterial surface in a K-12 strain. LT is a heteromeric toxin, and we determined that its cell surface localization was mediated by the its B subunit independent of an intact G M1 ganglioside binding site and that LT binds lipopolysaccharide and G M1 concurrently. The majority of LT secreted into the culture supernatant by the GSP in E. coli associated with vesicles. Only a mutation in hns, not overexpression of the GSP or LT, caused an increase in vesicle yield, supporting a specific vesicle formation machinery regulated by the nucleoidassociated protein HNS. We propose a model in which LT is secreted by the GSP across the outer membrane, secreted LT binds lipopolysaccharide via a G M1 -independent binding region on its B subunit, and LT on the surface of released outer membrane vesicles interacts with host cell receptors, leading to intoxication. These data explain a novel mechanism of vesicle-mediated receptor-dependent delivery of a bacterial toxin into a host cell. Enterotoxigenic Escherichia coli (ETEC)1 is an important pathogen responsible for traveler's diarrhea and Ͼ700,000 childhood deaths annually because of diarrhea in third world countries (1-4). ETEC produces two toxins implicated in the etiology of diarrhea, heat stabile toxin and heat-labile enterotoxin (LT) (1, 5). LT, which is encoded on a relatively uncharacterized 60-kb virulence plasmid (1), is one of a group of AB 5 toxins (6, 7) that also includes Shiga toxin, pertussis toxin, and cholera toxin (CT). These heteromeric toxins consist of a catalytic A subunit (LTA) and a pentamer of receptor-binding B subunits (LTB) (8, 9). In addition to structural homology, LT shares 80% sequence homology with the Vibrio cholerae toxin CT (10, 11). The ring-shaped B pentamer of both LT and CT mediates binding to the host epithelial receptor G M1 (12)(13)(14). LT is more promiscuous than CT in that it can also bind other receptors containing a terminal galactose (13). After binding, the receptor/toxin complex is internalized, and LTA is trafficked to the cytosol (13,15,16). Upon entry into the cytosol, the catalytic subunit constitutively activates adenylate cyclase, resulting in water and electrolyte efflux from the host cells (17).One major difference between the CT and LT lies in the fact that although CT is secreted from the cell, LT reportedly remains periplasmic (5, 18 -20). Some studies have also found LT to be associated with membranes extracellularly (3,21,22). Despite the equivalent activity that CT and LT exhibit in bioassays, disease caused by ETEC is much...

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Amino acid sequence homology between cholera toxin and Escherichia coli heat-labile toxin

Cited by 308 publications

References 25 publications

The purification of eukaryotic polypeptides synthesized in Escherichia coli

The purification of eukaryotic polypeptides synthesized in Escherichia coli

Acinetobacter calcoaceticusencoded mutarotase: nucleotide sequence analysis of the gene and characterization of its secretion inEscherichia coli

Bacterial Surface Association of Heat-labile Enterotoxin through Lipopolysaccharide after Secretion via the General Secretory Pathway

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