• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Transcription analysis of the nisin gene cluster in Lactococcus lactis ATCC 11454.
【24h】

Transcription analysis of the nisin gene cluster in Lactococcus lactis ATCC 11454.

机译：乳酸乳球菌ATCC 11454中乳链菌肽基因簇的转录分析。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The biosynthesis of the antimicrobial peptide nisin by Lactococcus lactis ATCC 11454 is subject to autoregulation. Transcriptions of nisABTCIP, where nisI encodes an immunity protein, and nisFEG, which encode an ABC transporter, are tightly induced by external nisin via the two-component system NisRK. One objective of this thesis is to study how sufficient immunity (NisI) can be expressed when the cell first encounters external nisin. In this study, Northern-blot and RT-PCR showed that nisI mRNA was present independent of nisA mRNA. Further mRNA stability study demonstrated that nisI mRNA had a much shorter half-life compared to nisA mRNA, suggesting that an internal promoter within nisABTCIP operon caused the independent nisI transcription that further provided cell immunity prior to the initiation of nisin auto-induction. The promoter was confirmed when the adjacent upstream region of nisI was fused to a probe vector, exhibiting constitutive promoter activity. The transcription start site (TSS) of the promoter was further mapped at 123 bp upstream of the ATG codon. Ordered 5' deletions revealed that transcription activation depended on sequences located up to -234 bp from the TSS.; Another objective of this thesis is to study the repressive mechanism of high growth temperature on nisin production. RT-PCR and Western-hybridization showed that nisR was transcribed and translated while nisA was repressed, eliminating the possibility that lack of NisRK caused the loss of nisA transcription. Gel shift experiments demonstrated no nisA-binding proteins present in cell extracts following a growth at 40°C, indicating lack of activated NisR at high growth temperature. Heparin column purification of nisA binding proteins and isolation of total phosphorylated proteins substantiated this finding as neither other repressor(s) nor phosphorylated NisR could be detected at 40°C. Therefore, it could be concluded that the absence of nisA transcription at 40°C was due to a lack of phosphorylated NisR which is needed to activate transcription of nisA. Further analysis of the NisK kinase activity at 40°C showed a significant repression, elucidating the reason of lacking phosphorylated NisR at 40°C. The relationship between reduced NisK kinase and cell morphology change was also discussed.
机译：乳酸乳球菌ATCC 11454对抗菌肽乳链菌肽的生物合成进行自动调节。 nisABTCIP的转录（其中nisI编码免疫蛋白，而nisFEG编码ABC转运蛋白）由外部乳链菌肽通过二组分系统NisRK紧密诱导。本论文的一个目的是研究当细胞首次遇到外部乳链菌肽时如何表达足够的免疫力（NisI）。在这项研究中，Northern印迹和RT-PCR显示nisI mRNA的存在独立于nisA mRNA。进一步的mRNA稳定性研究表明，与nisA mRNA相比，nisI mRNA的半衰期短得多，这表明nisABTCIP操纵子内部的内部启动子引起了独立的nisI转录，从而进一步在nisin自动诱导之前提供了细胞免疫力。当nisI的相邻上游区域与探针载体融合时，证实了启动子，该启动子具有组成型启动子活性。启动子的转录起始位点（TSS）被进一步定位在ATG密码子上游的123 bp处。有序的5'缺失揭示转录激活取决于距TSS高达-234bp的序列。本文的另一个目的是研究高生长温度对乳链菌肽生产的抑制机制。 RT-PCR和Western-hybridization表明nisR被转录和翻译，而nisA被抑制，从而消除了缺少NisRK导致nisA转录丢失的可能性。凝胶迁移实验表明，在40°C下生长后，细胞提取物中不存在nisA结合蛋白，这表明在高生长温度下缺少活化的NisR。 nisA结合蛋白的肝素柱纯化和总磷酸化蛋白的分离证实了这一发现，因为在40°C下都无法检测到其他阻遏物或磷酸化的NisR。因此，可以得出结论，在40°C下nisA转录不存在是由于缺少激活nisA转录所需的磷酸化NisR。对40°C时NisK激酶活性的进一步分析显示出明显的抑制作用，阐明了40°C时缺少磷酸化NisR的原因。还讨论了减少的NisK激酶与细胞形态变化之间的关系。

著录项

  • 作者

    Li, Haiping.;

  • 作者单位

    University of Minnesota.;

  • 授予单位 University of Minnesota.;
  • 学科 Biology Microbiology.; Agriculture Food Science and Technology.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 153 p.
  • 总页数 153
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 微生物学;农产品收获、加工及贮藏;
  • 关键词

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