IDENTIFICATION OF A 2ND TRANSCRIPTIONAL START SITE FOR THE INSECTICIDAL PROTEIN GENE CRYIVA OF BACILLUS-THURINGIENSIS SUBSP ISRAELENSIS

Expression of cryIVA, one of the insecticidal protein genes of B. thur ingiensis subsp. israelensis, is regulated at the transcriptional leve l. The cryIVA gene is specifically transcribed during the stationary p hase of this bacterium. As shown in our previous report [Yoshisue et a l. (1993a)], the transcription from the -364 position of the cryIVA ge ne is conducted by the major promoter P1 that is functional during mid dle stages of the stationary phase of B. thuringiensis. In the present study, we have identified a second transcriptional start point P2 for the cryIVA gene in addition to P1, the major transcriptional start po int. The transcription from P2 of the cryIVA gene occurred later than that from P1, during later stages of stationary phase of B. thuringien sis subsp. isi israelensis. The -10 and -35 nt sequences upstream from P2 of cryIVA are similar to those of the sigma(28)-specific promoters of B. thuringiensis genes and of the sigma(K)-specific promoters of B . subtilis genes. It is most likely that the region upstream from P2 o f cryIVA contains the nt sequences that determine the sigma(28)-specif ic promoter, the second one, for the cryIVA gene.