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Characterization of the Francisella virulence factor RipA.

机译：弗朗西斯菌毒力因子RipA的表征。

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摘要

Francisella tularensis is a highly virulent facultative intracellular pathogen; however, the mechanisms by which Francisella virulence factors mediate this virulence are not well defined. We identified the Francisella tularensis LVS FTL_1914 locus in a transposon mutagenesis screen for genes required for intraepithelial replication. Creation and characterization of a F. tularensis LVS DeltaripA strain revealed that the locus was necessary for intracellular replication and we termed the gene ripA (Required for Intracellular Propagation, Factor A). We have studied the Francisella virulence factor RipA in an attempt to define its importance in pathogenesis. RipA is required for Francisella virulence in a mouse model of tularemia. A Francisella DeltaripA mutant fails to replicate after intracellular colonization. The mutant invades at the same rate as wild type, escapes the phagosome, then fails to replicate in the cytoplasm. RipA localizes to the cytoplasmic membrane of Francisella and interacts with the transcriptional regulator IclR. How this interaction impacts virulence phenotypes and IclR transcriptional regulation are currently unknown. RipA is repressed by the Francisella virulence regulator MglA and is suppressed during intracellular growth after replication in the cytosol. MglA is upregulated after cell invasion. Most other virulence factors regulated by MglA are positively impacted by MglA suggesting that other factors act together with MglA to negatively influence gene expression. We screened a transposon library to identify loci that can influence ripA gene expression as identified using a lacZ reporter system. HU form B and NusA were identified as possible regulators that influence ripA expression. RipA may be part of a programmed gene response of Francisella during different stages in its intracellular lifecycle. MglA acting with other regulators may act to positively and negatively impact gene expression during different phases of intracellular growth and in the much more complex setting of in vivo pathogenesis.
机译：图拉弗朗西斯菌是一种高毒性兼性细胞内病原体。但是，弗朗西斯菌毒力因子介导这种毒力的机制尚不清楚。我们在转座子诱变筛选中确定上皮内弗朗西斯菌弗兰西氏菌LVS FTL_1914位点上皮内复制所需的基因。 F. tularensis LVS DeltaripA菌株的创建和表征表明该位点是细胞内复制所必需的，我们称其为ripA基因（细胞内繁殖所必需的因子A）。我们已经研究了弗朗西斯菌毒力因子RipA，以试图确定其在发病机理中的重要性。在tularemia小鼠模型中，Francisella毒力需要RipA。在细胞内定殖后，弗朗西斯菌DeltaripA突变体不能复制。突变体以与野生型相同的速率侵入，逃脱吞噬体，然后无法在细胞质中复制。 RipA定位到弗朗西斯菌的细胞质膜，并与转录调节因子IclR相互作用。目前尚不知道这种相互作用如何影响毒力表型和IclR转录调控。 RipA被弗朗西斯菌毒力调节剂MglA抑制，并在细胞质中复制后在细胞内生长期间受到抑制。细胞侵袭后，MglA上调。 MglA调节的大多数其他毒力因子都受到MglA的积极影响，这表明其他因子与MglA共同作用会对基因表达产生负面影响。我们筛选了一个转座子文库，以鉴定可以影响ripA基因表达的基因座，如使用lacZ报告系统所鉴定的。 HU形式B和NusA被确定为可能影响ripA表达的调节因子。 RipA可能是弗朗西斯菌在其细胞内生命周期不同阶段的程序化基因反应的一部分。 MglA与其他调节剂一起作用可能在细胞内生长的不同阶段以及体内致病机制更为复杂的过程中对基因表达产生正负影响。

著录项

  • 作者

    Fuller, James Robertson.;

  • 作者单位

    The University of North Carolina at Chapel Hill.;

  • 授予单位 The University of North Carolina at Chapel Hill.;
  • 学科 Biology Microbiology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 221 p.
  • 总页数 221
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 微生物学;
  • 关键词

  • 入库时间 2022-08-17 11:38:25

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