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首页> 美国卫生研究院文献>Infection and Immunity >Construction and Characterization of Moraxella catarrhalis Mutants Defective in Expression of Transferrin Receptors
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Construction and Characterization of Moraxella catarrhalis Mutants Defective in Expression of Transferrin Receptors

机译：转铁蛋白受体表达缺陷的卡他莫拉菌突变体的构建与鉴定

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We have previously reported the construction of an isogenic mutant defective in expression of OmpB1, the TbpB homologue, in Moraxella catarrhalis 7169. In this report, we have extended these studies by constructing and characterizing two new isogenic mutants in this clinical isolate. One mutant is defective in expression of TbpA, and the other mutant is defective in expression of both TbpA and TbpB. These isogenic mutants were confirmed by using PCR analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and sequencing. In vitro growth studies, comparing all three mutants, demonstrated that the tbpA mutant and the tbpAB mutant were severely limited in their ability to grow with human holotransferrin as the sole source of iron. In contrast, the ompB1 (tbpB) mutant was capable of utilizing iron from human transferrin, although not to the extent of the parental strain. While affinity chromatography with human holotransferrin showed that each Tbp was capable of binding independently to transferrin, solid-phase transferrin binding studies using whole cells demonstrated that the tbpA mutant exhibited binding characteristics similar to those seen with the wild-type bacteria. However, the ompB1 (tbpB) mutant exhibited a diminished capacity for binding transferrin, and no binding was detected with the double mutant. These data suggest that the M. catarrhalis TbpA is necessary for the acquisition of iron from transferrin. In contrast, TbpB is not essential but may serve as a facilitory protein that functions to optimize this process. Together these mutants are essential to provide a more thorough understanding of iron acquisition mechanisms utilized by M. catarrhalis.
机译：我们先前已经报道了在卡他莫拉氏菌7169中OmpB1（TbpB同源物）表达缺陷的同基因突变体的构建。在本报告中，我们通过在此临床分离株中构建和表征两个新的等基因突变体，扩展了这些研究。一个突变体在TbpA的表达上有缺陷，而另一个突变体在TbpA和TbpB的表达上都存在缺陷。通过PCR分析，十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和测序证实了这些同基因突变体。体外生长研究比较了所有三个突变体，结果表明，以人全转铁蛋白为唯一铁源，tbpA突变体和tbpAB突变体的生长能力受到严格限制。相反，ompB1（tbpB）突变体能够利用人转铁蛋白中的铁，尽管不能达到亲本菌株的程度。虽然用人全转铁蛋白进行的亲和层析表明每个Tbp都能够独立地与转铁蛋白结合，但使用全细胞进行的固相转铁蛋白结合研究表明，tbpA突变体表现出与野生型细菌相似的结合特性。但是，ompB1（tbpB）突变体显示出结合运铁蛋白的能力降低，并且没有检测到双重突变体的结合。这些数据表明，粘膜炎莫拉氏菌TbpA对于从转铁蛋白中获取铁是必需的。相反，TbpB不是必需的，但可以充当促进该过程优化的辅助蛋白。这些突变体一起对更深入地了解卡他莫拉氏菌利用的铁获取机制至关重要。

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