Lipoproteome screening of the Lyme disease agent identifies inhibitors of antibody-mediated complement killing.
Lipoproteome screening of the Lyme disease agent identifies inhibitors of antibody-mediated complement killing.
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DOI：
10.1073/pnas.2117770119
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发表时间：
2022-03-29
影响因子：
11.1
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中科院分区：
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螺旋体病原体编码丰富的脂蛋白，可以提供与宿主环境的关键接口。伯氏疏螺旋体，螺旋体生物学的模式物种，必须生存的地方性生活周期的波动之间的载体（蜱）和脊椎动物宿主。而B. burgdorferi表达超过80种表面脂蛋白-其中许多可能有助于宿主存活-B。Burgdorferi脂蛋白质组的特征很差。在这里，我们生成了一个平台来快速识别B的目标。burgdorferi表面脂蛋白，并鉴定了两种旁系同源物，其赋予对抗体引发的补体杀伤的抗性，所述抗体引发的补体杀伤可促进免疫活性宿主的存活。这项工作扩展了我们对补体逃避机制的理解，并指出了一种发现方法，用于识别螺旋体发病机制的宿主-病原体相互作用。螺旋体病原体，如莱姆病的病原体，广义伯氏疏螺旋体，编码丰富的脂蛋白;然而，部分由于它们与更充分研究的细菌，如变形菌门和厚壁菌门的进化距离，很少有螺旋体脂蛋白具有指定的功能。的确如此，B。Burgdorferi将其基因组的几乎8%用于脂蛋白基因，并且主要通过在其蜱媒介-脊椎动物宿主生命周期中产生至少80种表面暴露的脂蛋白与其环境相互作用。几个B。已显示伯氏脂蛋白在细胞粘附或免疫逃避中起作用，但大多数B的功能。Burgdorferi表面脂蛋白仍然是未知的。在这项研究中，我们开发了一个B。利用完整的螺旋体的伯氏脂蛋白组筛选平台，其能够鉴定先前未识别的宿主相互作用。由于螺旋体在血流中的存活对于传播是必不可少的，我们将筛选目标定位于C1，这是经典（抗体启动的）补体途径的第一组分。我们通过旁系同源脂蛋白ElpB和ElpQ（也分别称为ErpB和ErpQ）确定了两种高亲和力C1相互作用。使用生物化学，微生物学和生物物理学的方法，我们证明，ElpB和ElpQ结合的激活形式的C1蛋白酶，C1 r和C1 s，并代表一个独特的机械类C1抑制剂，保护螺旋体抗体介导的补体杀伤。除了确定补体抑制的模式之外，我们的研究还建立了一种脂蛋白组筛选方法，作为用于确定直接宿主-病原体相互作用的发现平台，所述直接宿主-病原体相互作用对螺旋体的发病机制至关重要，例如莱姆病病原体。
Spirochetal pathogens encode an abundance of lipoproteins that can provide a critical interface with the host environment. Borrelia burgdorferi, the model species for spirochetal biology, must survive an enzootic life cycle defined by fluctuations between vector (tick) and vertebrate host. While B. burgdorferi expresses over 80 surface lipoproteins—many of which likely contribute to host survival—the B. burgdorferi lipoproteome is poorly characterized. Here, we generated a platform to rapidly identify targets of B. burgdorferi surface lipoproteins and identified two paralogs that confer resistance to antibody-initiated complement killing that may promote survival in immunocompetent hosts. This work expands our understanding of complement evasion mechanisms and points toward a discovery approach for identifying host–pathogen interactions central to spirochete pathogenesis. Spirochetal pathogens, such as the causative agent of Lyme disease, Borrelia burgdorferi sensu lato, encode an abundance of lipoproteins; however, due in part to their evolutionary distance from more well-studied bacteria, such as Proteobacteria and Firmicutes, few spirochetal lipoproteins have assigned functions. Indeed, B. burgdorferi devotes almost 8% of its genome to lipoprotein genes and interacts with its environment primarily through the production of at least 80 surface-exposed lipoproteins throughout its tick vector–vertebrate host lifecycle. Several B. burgdorferi lipoproteins have been shown to serve roles in cellular adherence or immune evasion, but the functions for most B. burgdorferi surface lipoproteins remain unknown. In this study, we developed a B. burgdorferi lipoproteome screening platform utilizing intact spirochetes that enables the identification of previously unrecognized host interactions. As spirochetal survival in the bloodstream is essential for dissemination, we targeted our screen to C1, the first component of the classical (antibody-initiated) complement pathway. We identified two high-affinity C1 interactions by the paralogous lipoproteins, ElpB and ElpQ (also termed ErpB and ErpQ, respectively). Using biochemical, microbiological, and biophysical approaches, we demonstrate that ElpB and ElpQ bind the activated forms of the C1 proteases, C1r and C1s, and represent a distinct mechanistic class of C1 inhibitors that protect the spirochete from antibody-mediated complement killing. In addition to identifying a mode of complement inhibition, our study establishes a lipoproteome screening methodology as a discovery platform for identifying direct host–pathogen interactions that are central to the pathogenesis of spirochetes, such as the Lyme disease agent.