IMPROVED PRODUCTION OF THE INSECTICIDAL CRYIVD PROTEIN IN BACILLUS-THURINGIENSIS USING CRYLA(C) PROMOTERS TO EXPRESS THE GENE FOR AN ASSOCIATED 2O-KDA PROTEIN

Previous studies have shown that a 20-kDa protein enhances production of the insecticidal CytA and CryIVA proteins of Bacillus thuringiensis in Eschel ichin coli as well as CytA production and crystal formation in B. thuringiensis. To determine whether the 20-kDa protein could en hance CryIVD production, an expression vector was constructed with the 20-kDa open-reading frame under control of cryIA(c) promoters and the a cryIVD gene under control of its own promoter. Acrystalliferous cel ls of B. thuringiensis transformed with this plasmid, designated pWF53 , produced large bitrapezoidal CryIVD crystals that averaged 1.3 x 0.9 2 x 0.31 mu m, approximately fivefold larger in volume than wild-type CryIVD crystals, and 1.7 fold the volume of crystals produced using th e cryIVD operon, which contains the cryIVD gene and the gene for the 2 0-kDa protein. These results demonstrate that the 20-kDa protein signi ficantly improves net synthesis of CryIVD and promotes CryIVD crystal formation. Improved production of proteins as diverse as CryIVD and Cy tA by the 20-kDa protein indicates this protein may be useful in facil itating the production of other proteins.