...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Infection and immunity >Characterization of a defective diphtheria toxin repressor (dtxR) allele and analysis of dtxR transcription in wild-type and mutant strains of Corynebacterium diphtheriae.
【24h】

Characterization of a defective diphtheria toxin repressor (dtxR) allele and analysis of dtxR transcription in wild-type and mutant strains of Corynebacterium diphtheriae.

机译：缺陷的白喉毒素阻遏物（dtxR）等位基因的特征以及白喉棒状杆菌野生型和突变株中dtxR转录的分析。

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The production of diphtheria toxin and siderophore by the Corynebacterium diphtheriae regulatory mutant C7(beta)hm723 is resistant to the inhibitory effects of iron, and the mutant strain is defective for function of the regulatory gene dtxR. A 2.8-kb HindIII fragment carrying the C7(beta)hm723 dtxR allele was cloned and characterized in Escherichia coli. The restriction endonuclease maps of the 2.8-kb HindIII fragment from C7(beta)hm723 and the corresponding fragment from wild-type C. diphtheriae C7 were identical. RNA dot blot analysis with total RNA isolated from wild-type C. diphtheriae C7 and C7(beta)hm723 indicated that the dtxR gene was transcribed at very low but equivalent levels in both strains and was not regulated by iron. beta-Galactosidase synthesis from a tox-lacZ translational fusion construct in E. coli in high-iron medium was not repressed by the C7(beta)hm723dtxR allele, but was strongly repressed by the wild-type dtxR gene. The 28- to 29-kDa polypeptide expressed from the mutant dtxR allele in E. coli had the same electrophoretic mobility as the wild-type dtxR gene product in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The nucleotide sequence of the coding region and the 5' upstream region of the C7(beta)hm723 dtxR allele was determined and compared with the wild-type nucleotide sequence. The dtxR allele from C7(beta)hm723 contained a single-base change located 140 nucleotides from the 5' start of the gene, which resulted in replacement of arginine in the wild-type sequence by histidine in the mutant protein. These data demonstrate that C7(beta)hm723 expresses a mutant DtxR repressor protein that is severely defective in repressor activity.
机译：白喉棒状杆菌调节突变体C7βhm723对白喉毒素和铁载体的产生对铁的抑制作用有抵抗力，并且该突变株对于调节基因dtxR的功能是有缺陷的。在大肠杆菌中克隆并鉴定了带有C7βhm723dtxR等位基因的2.8kb HindIII片段。来自C7βhm723的2.8kb HindIII片段和来自野生型白喉衣原体C7的相应片段的限制性核酸内切酶图是相同的。用从野生型白喉衣原体C7和C7βhm723分离的总RNA的RNA点印迹分析表明，dtxR基因在两个菌株中以非常低但相等的水平被转录并且不受铁的调节。在高铁培养基中从大肠杆菌中的tox-lacZ翻译融合构建体合成β-半乳糖苷酶不受C7βhm723dtxR等位基因的抑制，但受野生型dtxR基因的抑制。在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳中，由突变dtxR等位基因在大肠杆菌中表达的28-29kDa多肽具有与野生型dtxR基因产物相同的电泳迁移率。确定了C7βhm723dtxR等位基因的编码区和5'上游区的核苷酸序列，并将其与野生型核苷酸序列进行比较。 C7βhm723的dtxR等位基因包含一个单碱基改变，位于该基因5'端140个核苷酸处，这导致突变蛋白中的组氨酸取代了野生型序列中的精氨酸。这些数据证明，C7βhm723表达了在阻遏物活性上严重缺陷的突变体DtxR阻遏物蛋白。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号