title: Factors regulating cryIVB expression in the cyanobacterium--Synechococcus PCC 7942.
abstract: The expression of the larvicidal Bacillus thuringiensis subsp. israelensis cryIVB gene in cyanobacteria has been suggested to be an effective means of controlling mosquito populations. Using a variety of cryIVB constructs, in this study we have examined the effect of Synechococcus PCC 7942 culture age on intracellular toxin levels and have attempted to determine the mechanisms by which cryIVB gene expression is regulated. The data suggest that specific degradation of the cryIVB mRNA limits toxin production; however, the addition of cyanobacterial 3' untranslated DNA sequences to the cryIVB gene did not improve mRNA stability or toxin levels. An analysis of the cryIVB sequence and comparison of codon usage patterns with highly expressed cyanobacterial genes suggest that inefficient translation and intragenic ribosomal binding sites impede protein synthesis and result in rapid turnover of the toxin mRNA.
authors.affiliation: Dept. of Botany, University of Toronto, Ontario, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Soltes-Rak
authors.forename: D J
authors.initials: DJ
authors.lastname: Kushner
authors.forename: D D
authors.initials: DD
authors.lastname: Williams
authors.forename: J R
authors.initials: JR
authors.lastname: Coleman
mesh_terms: D001413:Bacillus thuringiensis / Q000737:chemistry* / Q000235:genetics; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D001427:Bacterial Toxins; D001483:Base Sequence; D003062:Codon / Q000235:genetics; D000458:Cyanobacteria / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004731:Endotoxins / Q000096:biosynthesis* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D006460:Hemolysin Proteins; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000096:biosynthesis / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis*; D012270:Ribosomes / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003062:Codon; D004269:DNA, Bacterial; D004731:Endotoxins; D006460:Hemolysin Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis