New Insight into Filamentous Hemagglutinin Secretion Reveals a Role for Full-Length FhaB in Bordetella Virulence.
New Insight into Filamentous Hemagglutinin Secretion Reveals a Role for Full-Length FhaB in Bordetella Virulence.
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DOI：
10.1128/mbio.01189-15
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发表时间：
2015-08-18
期刊：
影响因子：
6.4
通讯作者：
Cotter PA
中科院分区：
文献类型：
--
作者：
Melvin JA;Scheller EV;Noël CR;Cotter PA
博德特氏菌丝状血凝素（FHA）是无细胞百日咳疫苗的主要成分，有助于毒力，但其机制尚不清楚。FHA首先合成为约370-kDa的前原蛋白，称为FhaB。在分泌过程中去除N-末端信号肽和一个大的C-末端前结构域（PD）导致“成熟”~250-kDa FHA，这被认为是蛋白质的生物活性形式。FhaB的两个C-末端亚结构域的缺失不影响功能性FHA的产生，并且突变菌株与野生型细菌在粘附于下呼吸道和抑制小鼠肺部炎症的能力方面无法区分。然而，产生改变的Fha B分子的突变菌株从下呼吸道中消除的速度比野生型支气管炎B杆菌快得多，表明对早期免疫介导的清除的抗性缺陷。我们的结果出乎意料地揭示了全长Fha B在支气管败血B杆菌在下呼吸道中的持续存在中起着关键作用。博德特氏菌丝状血凝素（FHA）是无细胞百日咳疫苗的主要成分，也是重要的毒力因子。FHA最初是作为一种大蛋白质产生的，在分泌到细菌表面的过程中被加工。与大多数加工蛋白质一样，FHA的成熟形式被认为是蛋白质的功能形式。然而，我们的研究结果表明，全长形式在体内毒力中起着至关重要的作用。此外，我们发现FHA含有加工的分子内调节因子，并且这种加工控制是其毒力活动不可或缺的一部分。本报告强调了同时研究蛋白质成熟和功能的优势，因为全长形式的FHA的作用仅从体内感染研究中显而易见，而不是从FHA生产或成熟的体外研究中，甚至从体外毒力相关活性测定中。
Bordetella filamentous hemagglutinin (FHA), a primary component of acellular pertussis vaccines, contributes to virulence, but how it functions mechanistically is unclear. FHA is first synthesized as an ~370-kDa preproprotein called FhaB. Removal of an N-terminal signal peptide and a large C-terminal prodomain (PD) during secretion results in “mature” ~250-kDa FHA, which has been assumed to be the biologically active form of the protein. Deletion of two C-terminal subdomains of FhaB did not affect production of functional FHA, and the mutant strains were indistinguishable from wild-type bacteria for their ability to adhere to the lower respiratory tract and to suppress inflammation in the lungs of mice. However, the mutant strains, which produced altered FhaB molecules, were eliminated from the lower respiratory tract much faster than wild-type B. bronchiseptica, suggesting a defect in resistance to early immune-mediated clearance. Our results revealed, unexpectedly, that full-length FhaB plays a critical role in B. bronchiseptica persistence in the lower respiratory tract. The Bordetella filamentous hemagglutinin (FHA) is a primary component of the acellular pertussis vaccine and an important virulence factor. FHA is initially produced as a large protein that is processed during secretion to the bacterial surface. As with most processed proteins, the mature form of FHA has been assumed to be the functional form of the protein. However, our results indicate that the full-length form plays an essential role in virulence in vivo. Furthermore, we have found that FHA contains intramolecular regulators of processing and that this control of processing is integral to its virulence activities. This report highlights the advantage of studying protein maturation and function simultaneously, as a role for the full-length form of FHA was evident only from in vivo infection studies and not from in vitro studies on the production or maturation of FHA or even from in vitro virulence-associated activity assays.