Full expression of the cryIIIA toxin gene of Bacillus thuringiensis requires a distant upstream DNA sequence affecting transcription.
J Bacteriol
; 175(10): 2952-60, 1993 May.
Article
em En
| MEDLINE
| ID: mdl-8491716
ABSTRACT
The cryIIIA gene encoding a coleopteran-specific toxin is poorly expressed in Bacillus thuringiensis when cloned in a low-copy-number plasmid. This weak expression is observed when the gene is cloned only with its promoter and its putative terminator. cryIIIA gene expression was analyzed by using deletion derivatives of a larger DNA fragment carrying the toxin gene and additional adjacent sequences. The results indicate that a 1-kb DNA fragment located 400 bp upstream of the promoter strongly enhances CryIIIA production in B. thuringiensis sporulating cells. Similar results were obtained when the low-copy-number plasmid pHT304 carrying transcriptional fusions between upstream regions of cryIIIA and the lacZ gene was used. Analysis of the start sites, the sizes, and the amounts of cryIIIA-specific mRNAs shows that the enhancement occurs at the transcriptional level by increasing the number of cryIIIA-specific transcripts from the onset of sporulation to about 6 h after the onset of sporulation. The nucleotide sequence of the 1-kb activating fragment and of the 700 bp containing the promoter region and the 5' end of cryIIIA were determined. No potential protein-coding sequences were found upstream of the promoter. The major characteristic of the 1-kb activating fragment is the presence of a 220-bp A + T-rich region.
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Base de dados:
MEDLINE
Assunto principal:
Bacillus thuringiensis
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Proteínas de Bactérias
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Toxinas Bacterianas
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Transcrição Gênica
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Sequências Reguladoras de Ácido Nucleico
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Endotoxinas
Idioma:
En
Revista:
J Bacteriol
Ano de publicação:
1993
Tipo de documento:
Article
País de afiliação:
França