IDENTIFICATION OF A PROMOTER FOR THE CRYSTAL PROTEIN-ENCODING GENE CRYIVB FROM BACILLUS-THURINGIENSIS SUBSP ISRAELENSIS

The cryIVB gene of Bacillus thuringiensis subsp. israelensis (Bti) cod es for a 135-kDa insecticidal crystal protein, which is specifically t oxic to dipteran larvae. We have identified a transcription start poin t (tsp) of cryIVB by a primer extension experiment. The promoter seque nce alignment, together with the chronology of appearance of the trans cript, suggested that cryIVB is transcribed by RNA polymerase containi ng sigma(35) (E sigma(35)). This was confirmed by investigation of cry IVB transcription in several Bacillus subtilis sporulation mutants. Un like the lepidopteran-specific crystal protein-encoding genes [cryIA(a ) and cryIB], transcription of which is regulated by both sigma(35) an d sigma(28), cryIVB transcription was controlled only by the sigma(35) -dependent promoter at the midsporulation stage.