EXPRESSION OF THE GENES FOR INSECTICIDAL CRYSTAL PROTEINS IN BACILLUS-THURINGIENSIS - CRYIVA, NOT CRYIVB, IS TRANSCRIBED BY RNA-POLYMERASE CONTAINING SIGMA(H) AND THAT CONTAINING SIGMA(E)

To investigate the mechanism of transcriptional regulation of cryIVA a nd cryIVB, encoding 130-kDa dipteran-active crystal proteins, in Bacil lus thuringiensis subsp, israelensis, we introduced each gene into sev eral sporulation mutants of Bacillus subtilis. A spollG mutation, the wild-type gene of which encodes sigma(E) precursor, completely blocked the cryIVB transcription. In contrast, low but detectable transcripti on of cryIVA was observed in the spollG mutant. In the wild-type B. su btilis, no transcription of cryIVB was detected before T-2 (2 h after the onset of stationary phase), while the cryIVA transcription started at the late exponential phase at low levels. Furthermore, in a wild-t ype strain of B. thuringiensis subsp. israelensis, transcription of cr yIVA began earlier than that of genes encoding other crystal component s, cryIVB and cytA. A consensus sequence recognized by an RNA polymera se containing sigma(H) of B. subtilis was found upstream of the transc ription start point of cryIVA, which overlapped with that recognized b y sigma(E).