Lectin-like binding of Bacillus thuringiensis var. kurstaki lepidopteran-specific toxin is an initial step in insecticidal action.
The two delta-endotoxins comprising the Bacillus thuringiensis var. kurstaki HD1 insecticidal protein crystal were separated. The lepidopteran-specific protoxin was activated in vitro and its mechanism of action investigated. Toxicity towards Choristoneura fumiferana CF1 cells was specifically inhibited by preincubation of the toxin with N-acetylgalactosamine and N-acetylneuraminic acid. The lectins soybean agglutinin and wheat germ agglutinin, which bind N-acetylgalactosamine, also inhibited toxicity. Since N-acetylneuraminic acid is not known to occur in insects, these results suggest that the toxin may recognise a specific plasma membrane glycoconjugate receptor with a terminal N-acetylgalactosamine residue.
Knowles
B H
BH
Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 IQW, England.
Thomas
W E
WE
Ellar
D J
DJ
D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism* / Q000472:pathogenicity; D002460:Cell Line; D004731:Endotoxins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D037102:Lectins / Q000378:metabolism*; D007915:Lepidoptera / Q000382:microbiology; D011956:Receptors, Cell Surface / Q000378:metabolism*
D004731:Endotoxins; D037102:Lectins; D011956:Receptors, Cell Surface