Diphtheria toxin has the properties of a lectin
The inhibition of protein synthesis in Chinese hamster V79 cells by diphtheria toxin is antagonized by the lectins concanavalin A, succinylated concanavalin A, and wheat germ agglutinin but not by Proteus vulgaris phytohemagglutinin or abrus agglutinin. The effects of concanavalin A and wheat germ agglutinin are reversed by methyl alpha-mannoside and N-acetylglucosamine, respectively. The inhibition of diphtheria toxin as a function of concanavalin A concentration fits a model of competitive inhibition with an apparent dissociation constant for concanavalin A of 3 X 10(-8) M. These results suggest that the diphtheria toxin receptor may be an oligosaccharide. To test this hypothesis, we screened several oligosaccharides for the ability to inhibit diphtheria toxin. The cell wall polysaccharide of Salmonella cholera suis and the ovalbumin glycopeptide were effective inhibitors. These studies suggest that diphtheria toxin may have the oligosaccharide binding properties of a lectin with specificity for N-acetylglucosamine and mannose.
Additional Information© 1978 by the National Academy of Sciences. Communicated by Nathan O. Kaplan, November 7, 1977. We thank Dr. Immo Scheffler for valuable discussion, Dr. Hud Freeze for a sample of ovalbumin glycopeptide, Dr. N. Kaplan for diphtheria toxin, Dr. S. Sarkar for mannan samples, and D. Eurey for skilled technical assistance. D.C. is a University of California Regents Predoctoral Fellow; R.D. is supported by a U.S. Public Health Service Postdoctoral Fellowship GM-07199. The costs of publication of this article were defrayed in part by the payment of page charges This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Published - DRApnas78.pdf