Abstract: The Bacillus thuringiensis var. kurstaki HD-73 crystal protein gene was cloned into pBR322. E. coli cells harboring this recombinant plasmid produced a 130 kD protoxin that was toxic to Manduca sexta (tobacco hornworm) larvae. Plasmids having the 3′-end of the protoxin gene deleted where also constructed. E. coli cells harboring these deleted plasmids produced an active, soluble 68 kD toxin, provided that the 3′-deletion had not removed sequences encoding the 68 kD toxin. The invention provides methods to produce 68 kD toxin protein by constructing partial protoxin genes encoding the toxin followed by expression of the genes in living cells. Useful plasmids and cells are also provided.

Abstract: The Bacillus thuringiensis var. kurstaki HD-73 crystal protein gene was cloned into pBR322. E. coli cells harboring this recombinant plasmid produced a 130 kD protoxin that was toxic to Manduca sexta (tobacco hornworm) larvae. Plasmids having the 3′-end of the protoxin gene deleted where also constructed. E. coli cells harboring these deleted plasmids produced an active, soluble 68 kD toxin, provided that the 3′-deletion had not removed sequences encoding the 68 kD toxin. The invention provides methods to produce 68 kD toxin protein by constructing partial protoxin genes encoding the toxin followed by expression of the genes in living cells. Useful plasmids and cells are also provided.