DegP Initiates Regulated Processing of Filamentous Hemagglutinin in Bordetella bronchiseptica.
DegP Initiates Regulated Processing of Filamentous Hemagglutinin in Bordetella bronchiseptica.
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DOI：
10.1128/mbio.01465-21
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发表时间：
2021-06-29
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：
Johnson RM;Nash ZM;Dedloff MR;Shook JC;Cotter PA
丝状血凝素（FhaB）是百日咳博德特氏菌（百日咳的致病因子）和密切相关的支气管败血博德特氏菌的关键毒力因子。FhaB是一种粘附素，抑制炎症细胞因子的产生，并在感染期间防止吞噬细胞清除。在小鼠中建立持续感染需要FhaB C-末端前结构域的调节降解。两种蛋白酶，CtpA在周质和SphB 1的细菌表面上，已知介导FhaB加工，我们最近确定，CtpA的功能之前，并控制FhaB切割位点，SphB 1。然而，数据表明，另一种周质蛋白酶必须通过去除抑制CtpA介导的降解的FhaB C末端的一部分来启动前结构域的降解。使用候选方法，我们将DegP确定为起始蛋白酶。缺失degP或取代其预测的催化残基导致FHA′（FhaB加工的主要产物）的产生减少，并在全细胞裂解物中积累全长FhaB。此外，在degP突变体中，FHA′不再释放到培养上清液中。解除CtpA抑制的FhaB C末端的改变消除了对DegP的需要，这与在加工途径中DegP先于CtpA起作用一致。DegP不是通过FhaC分泌FhaB或细菌粘附于宿主细胞所需的，表明DegP主要作为蛋白酶而不是B中FhaB的伴侣。支气管炎我们的研究结果突出了HtrA家族蛋白酶在致病菌毒力因子激活中的作用。
Filamentous hemagglutinin (FhaB) is a critical virulence factor for both Bordetella pertussis, the causal agent of whooping cough, and the closely related species Bordetella bronchiseptica. FhaB is an adhesin, suppresses inflammatory cytokine production, and protects against phagocytic cell clearance during infection. Regulated degradation of the FhaB C-terminal prodomain is required to establish a persistent infection in mice. Two proteases, CtpA in the periplasm and SphB1 on the bacterial surface, are known to mediate FhaB processing, and we recently determined that CtpA functions before, and controls the FhaB cleavage site of, SphB1. However, the data indicate that another periplasmic protease must initiate degradation of the prodomain by removing a portion of the FhaB C terminus that inhibits CtpA-mediated degradation. Using a candidate approach, we identified DegP as the initiating protease. Deletion of degP or substitution of its predicted catalytic residue resulted in reduced creation of FHA′ (the main product of FhaB processing) and an accumulation of full-length FhaB in whole-cell lysates. Also, FHA′ was no longer released into culture supernatants in degP mutants. Alterations of the FhaB C terminus that relieve inhibition of CtpA abrogate the need for DegP, consistent with DegP functioning prior to CtpA in the processing pathway. DegP is not required for secretion of FhaB through FhaC or for adherence of the bacteria to host cells, indicating that DegP acts primarily as a protease and not a chaperone for FhaB in B. bronchiseptica. Our results highlight a role for HtrA family proteases in activation of virulence factors in pathogenic bacteria.