FIG. 1.

Major steps in the construction of vectors for expressing the cry3A gene with and without the STAB-SD sequence under the control of cyt1A promoters. (A) A HindIII fragment from B. thuringiensis subsp. morrisoni (strain tenebrionis) containing the cry3A gene was cloned into pUC13, generating pUC13-Btt. (B) Copies of cry3A with and without the STAB-SD sequence were generated by PCR and cloned into the SmaI site downstream from the dual cytA promoters of the E. coli-B. thuringiensis shuttle vector pHT3101. This yielded the expression vectors pPFT3As and pPFT3A for expressing, respectively, cry3A with and without the STAB-SD sequence under the control of the dual sporulation-dependent cytA promoters.