Genetic analysis of cryIIIA gene expression in Bacillus thuringiensis.
The Bacillus thuringiensis (Bt) cryIIIA gene is regulated by a different mechanism from that of most of the other cry genes. Its expression begins during late-exponential growth and not during sporulation as for the other classes of cry genes. Moreover, in Bacillus subtilis, cryIIIA expression is independent of the major sporulation-specific sigma factors and is increased in a spoOA genetic background. We used lacZ fusions and primer-extension analysis to follow the time-course of cryIIIA transcription in Bt wild-type and in various Spo- genetic backgrounds (spoOA, sigE and sigK). cryIIIA was activated from the end of vegetative growth to stage II of sporulation (t3) in the wild-type strain. Thereafter, transcription from the same promoter continued, at a decreasing rate, until the end of stage III. In the spoOA mutant strain, the same promoter was activated for at least 15 h during the stationary phase. cryIIIA activation in the sigK genetic background was similar to that in the wild-type but was extended in a sigma E mutant strain. Thus cryIIIA expression in Bt is not directly dependent on the major sporulation-specific sigma factors. Furthermore, an event linked with the thE-dependent period of sporulation ends cryIIIA activation, although transcription of this gene does not switch off before the end of stage III.
Salamitou
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S
Unité de Biochimie Microbienne, Centre National de la Recherche Scientifique URA 1300, Institut Pasteur, Paris, France.
Agaisse
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H
Bravo
A
A
Lereclus
D
D
D001413:Bacillus thuringiensis / Q000235:genetics* / Q000502:physiology; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics*; D001427:Bacterial Toxins; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004731:Endotoxins / Q000096:biosynthesis* / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013045:Species Specificity; D013171:Spores, Bacterial; D013997:Time Factors; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000096:biosynthesis
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D017931:DNA Primers; D004731:Endotoxins; D006460:Hemolysin Proteins; D011993:Recombinant Fusion Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D001616:beta-Galactosidase