Analysis of cryIAa expression in sigE and sigK mutants of Bacillus thuringiensis

Mol Gen Genet. 1996 Apr 10;250(6):734-41. doi: 10.1007/BF02172985.

Abstract

The sigE and sigK genes, encoding the sporulation-specific sigma factors sigma 35 and sigma 28 of Bacillus thuringiensis, were each disrupted by inserting a gene conferring resistance to kanamycin into their coding sequences. The B. thuringiensis SigE- and sigK- mutant strains were blocked at different sporulation stages and were unable to sporulate. The SigE-strain was blocked at stage II of sporulation, whereas the SigK- strain was blocked at stage IV. The expression of a cryIAa'-'lacZ transcriptional fusion was analysed in these genetic backgrounds and it was found that both sigma factors are involved in the in vivo transcription of this gene. However, the SigK- strain harbouring the cryIAa gene produced amounts of toxin similar to those produced by the B. thuringiensis Spo+ strain. The toxins accumulated in the mother cell compartment to form a crystal inclusion which remained encapsulated within the cell wall. Thus, transcription from the sigma E-dependent promoter alone (Bt I promoter) is sufficient to support high levels of toxin production in B. thuringiensis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus thuringiensis / genetics*
  • Bacillus thuringiensis / metabolism
  • Bacillus thuringiensis / physiology
  • Bacillus thuringiensis / ultrastructure
  • Bacillus thuringiensis Toxins
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / physiology
  • Bacterial Toxins / biosynthesis
  • Bacterial Toxins / genetics*
  • Base Sequence
  • DNA Primers
  • Electrophoresis, Polyacrylamide Gel
  • Endotoxins / biosynthesis
  • Endotoxins / chemistry
  • Endotoxins / genetics*
  • Gene Expression Regulation, Bacterial / genetics
  • Hemolysin Proteins
  • Kanamycin / pharmacology
  • Lac Operon
  • Microscopy, Electron
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Pest Control, Biological
  • Promoter Regions, Genetic
  • Recombinant Fusion Proteins / biosynthesis
  • Sigma Factor / genetics*
  • Sigma Factor / physiology
  • Spores, Bacterial / physiology
  • Transcription Factors / genetics*
  • Transcription Factors / physiology
  • Transcription, Genetic / genetics
  • beta-Galactosidase / metabolism

Substances

  • Bacillus thuringiensis Toxins
  • Bacterial Proteins
  • Bacterial Toxins
  • DNA Primers
  • Endotoxins
  • FliA protein, Bacteria
  • Hemolysin Proteins
  • Recombinant Fusion Proteins
  • Sigma Factor
  • Transcription Factors
  • insecticidal crystal protein, Bacillus Thuringiensis
  • sporulation-specific sigma factors
  • Kanamycin
  • beta-Galactosidase