Regions important for the adhesin activity of Moraxella catarrhalis Hag
Regions important for the adhesin activity of Moraxella catarrhalis Hag
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DOI：
10.1186/1471-2180-7-65
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发表时间：
2007-07-03
期刊：
影响因子：
4.2
通讯作者：
Lafontaine, Eric R.
中科院分区：
文献类型：
--
作者：
Bullard, Brian;Lipski, Serena;Lafontaine, Eric R.
背景资料：卡他莫拉菌Hag蛋白是一种Oca自身转运蛋白粘附素，它对卡他莫拉菌粘附于人中耳和A549肺细胞具有重要作用。卡他等基因hag突变株对人上皮细胞系Chang（结膜）和NCIH 292（肺）的抑制作用降低了50- 93%。此外，在异源大肠杆菌背景中表达Hag显著增加了重组细菌对NCIH 292细胞和鼠IV型胶原的粘附。然而，Hag并没有增加E. coli转化为Chang细胞。这些结果表明，Hag直接介导对NCIH 292肺细胞和胶原的粘附，但不足以赋予与结膜单层的结合。在M的hag基因内设计了几个框内缺失。卡他菌菌株O35 E，并测试所得蛋白介导与NCIH 292单层、中耳细胞和IV型胶原结合的能力。这些实验表明，上皮细胞和胶原蛋白的结合特性是可分离的，并且这种类似于2，000个氨基酸的蛋白质的残基385 - 705对于粘附到中耳和NCIH 292细胞是重要的。还发现O35 E-Hag区域包括氨基酸706至1194，是粘附胶原蛋白所需的。相反，β-roll重复存在于Hag中，这是在几种Oca粘附素中保守的结构特征，并负责小肠结肠炎耶尔森菌YadA的粘附特性，对于Hag介导的adherence.Conclusion：Hag是来自与M致病相关的各种解剖部位的人类细胞的主要粘附因子。卡他病及其结构-功能关系不同于其它密切相关的自转运蛋白。
Background: The Moraxella catarrhalis Hag protein, an Oca autotransporter adhesin, has previously been shown to be important for adherence of this respiratory tract pathogen to human middle ear and A549 lung cells.Results: The present study demonstrates that adherence of M. catarrhalis isogenic hag mutant strains to the human epithelial cell lines Chang (conjunctival) and NCIH292 (lung) is reduced by 50-93%. Furthermore, expressing Hag in a heterologous Escherichia coli background substantially increased the adherence of recombinant bacteria to NCIH292 cells and murine type IV collagen. Hag did not, however, increase the attachment of E. coli to Chang cells. These results indicate that Hag directly mediates adherence to NCIH292 lung cells and collagen, but is not sufficient to confer binding to conjunctival monolayers. Several in-frame deletions were engineered within the hag gene of M. catarrhalis strain O35E and the resulting proteins were tested for their ability to mediate binding to NCIH292 monolayers, middle ear cells, and type IV collagen. These experiments revealed that epithelial cell and collagen binding properties are separable, and that residues 385 705 of this similar to 2,000 amino acid protein are important for adherence to middle ear and NCIH292 cells. The region of O35E-Hag encompassing aa 706 to 1194 was also found to be required for adherence to collagen. In contrast, beta-roll repeats present in Hag, which are structural features conserved in several Oca adhesins and responsible for the adhesive properties of Yersinia enterocolitica YadA, are not important for Hag-mediated adherence.Conclusion: Hag is a major adherence factor for human cells derived from various anatomical sites relevant to pathogenesis by M. catarrhalis and its structure-function relationships differ from those of other, closely-related autotransporter proteins.