Digalactosylceramide is the receptor for staphylococcal enterotoxin-B in human kidney proximal tubular cells.
We have characterized a glycosphingolipid (GSL) receptor for Staphylococcus enterotoxin-B (SEB) in cultured human kidney proximal tubular (PT) cells. Solid-phase binding of [125I]SEB to the GSL receptor was concentration dependent and was not displaceable by two structurally related toxins, such as staphylococcal enterotoxin-A and toxic shock syndrome toxin-1. Rat kidney cells did not bind [125I]SEB. However, when the rat kidney cells were pre-incubated with digalactosylceramide, there was a concentration-dependent binding of [125I]SEB. Trimethylsilyl derivatization of methyl glycosides, followed by gas-liquid chromatography-mass spectrometry (GC-MS), revealed that galactose was the major sugar component of this putative receptor GSL. The sphingosines present in this GSL were d18:2, d22:2 and d23:0; the fatty acids present were palmitate, oleate and stearate. Permethylation of alditol acetates and GC-MS revealed two predominant sugars, namely 2, 3, 4 and 6 tetramethylgalactital and 2, 3 and 6 trimethylgalactital. The GSL receptor for SEB was sensitive to alpha-galactosidase, and resistant to beta-galactosidase and beta-glucosidase. Taken together, our studies reveal that the tentative structure of the receptor for SEB in human kidney PT cells is CerGal alpha 1-->4Gal. In summary, we have identified a GSL as one of the binding sites of SEB, a food-borne toxin. We believe that our finding may open up rational approaches for the therapy of SEB-induced glycopathology in man.
Chatterjee
S
S
Department of Pediatrics, Johns Hopkins University, School of Medicine, Baltimore, MD 21287-3654, USA.
Khullar
M
M
Shi
W Y
WY
D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D004768:Enterotoxins / Q000378:metabolism*; D005227:Fatty Acids / Q000032:analysis; D005699:Galactosylceramides / Q000737:chemistry / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism*; D008697:Methane / Q000378:metabolism; D051381:Rats; D013110:Sphingosine / Q000032:analysis; D013211:Staphylococcus aureus / Q000378:metabolism*
D004768:Enterotoxins; D005227:Fatty Acids; D005699:Galactosylceramides; C031818:enterotoxin B, staphylococcal; D013110:Sphingosine; D008697:Methane