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  • 标题:Molecular cloning and DNA sequence analysis of a diphtheria tox iron-dependent regulatory element (dtxR) from Corynebacterium diphtheriae.
  • 本地全文:下载
  • 作者:J Boyd ; M N Oza ; J R Murphy
  • 期刊名称:Proceedings of the National Academy of Sciences
  • 印刷版ISSN:0027-8424
  • 电子版ISSN:1091-6490
  • 出版年度:1990
  • 卷号:87
  • 期号:15
  • 页码:5968-5972
  • DOI:10.1073/pnas.87.15.5968
  • 语种:English
  • 出版社:The National Academy of Sciences of the United States of America
  • 摘要:Although the structural gene for diphtheria toxin, tox, is carried by a family of closely related corynebacteriophages, the regulation of tox expression is controlled, to a large extent, by its bacterial host Corynebacterium diphtheriae. Optimal yields of tox gene products are obtained only when iron becomes the growth-rate-limiting substrate. Previous studies suggest that regulation of tox expression is mediated through an iron-binding aporepressor. To facilitate molecular cloning of the tox regulatory element from genomic libraries of C. diphtheriae, we constructed a tox promoter/operator (toxPO)-lacZ transcriptional fusion in Escherichia coli strain DH5 alpha. We report the molecular cloning and nucleic acid sequence of a diphtheria tox iron-dependent regulatory element, dtxR, and demonstrate that expression of beta-galactosidase from the toxPO-lacZ fusion is regulated by dtxR-encoded protein in an iron-sensitive manner. In addition, we show that expression of the toxPO-lacZ fusion is not affected by the E. coli iron-regulatory protein Fur and that the dtxR protein does not inhibit expression of fur-regulated outer-membrane proteins.
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