RESUMO
A genomic clone of an acyl carrier protein gene (Bcg4-4) which is highly expressed in developing embryos of Brassica rapa was isolated and sequenced. The promoter and transcription terminator regions of Bcg4-4 were used to express a beta-glucuronidase reporter gene in transgenic rapeseed. Deletion of repeated domains in the promoter region did not lower beta-glucuronidase expression in seeds.
Assuntos
Proteína de Transporte de Acila/genética , Brassica/genética , Regiões Promotoras Genéticas , Sequência de Aminoácidos , Sequência de Bases , DNA/genética , DNA/isolamento & purificação , Genes de Plantas , Biblioteca Genômica , Glucuronidase/genética , Glucuronidase/metabolismo , Dados de Sequência Molecular , Plantas Geneticamente Modificadas , Sequências Repetitivas de Ácido Nucleico , Sementes/fisiologia , Regiões Terminadoras Genéticas , Transcrição GênicaRESUMO
The CYC7 gene of Saccharomyces cerevisiae encodes the minor species, iso-2, of the cytochrome c protein. Its expression is governed by two regulatory sequences upstream from the gene: a positive site which stimulates transcription 240 base pairs 5' from the protein-coding sequence (-240) and a negative site which inhibits transcription at -300. In this study, the nature of the positive site and its relationship to the negative site has been investigated. Expression of the CYC7 gene is weakly inducible by oxygen. This effect was greatly enhanced by the semidominant CYP1-16 mutation in the trans-acting gene CYP1. The weak oxygen regulation in wild-type cells and the enhanced induction in CYP1-16 mutants were found to be mediated through the positive site. A mutational analysis of this site implicated at least part of a tandem, direct repeat of 9 base pairs as essential for the functioning of this site. The relationship between the positive and negative sites was investigated by comparing the expression of the intact gene with that of derivatives lacking either one or the other site. The expression of the gene containing only the negative site was actually stimulated anaerobically, while the gene containing the positive site alone, although having higher expression aerobically than anaerobically, had higher anaerobic expression than did the intact gene. Thus, it appeared that the combination of the positive and negative sites suppressed anaerobic expression. A model which attempts to explain these properties of the two sites and account for the regulation of the expression of the intact gene is presented.