PDF(Pubmed)
Abstract：
Bacterial adhesion is a fundamental process which enables colonisation of niche environments and is key for infection. However, in Legionella pneumophila, the causative agent of Legionnaires\' disease, these processes are not well understood. The Legionella collagen-like protein (Lcl) is an extracellular peripheral membrane protein that recognises sulphated glycosaminoglycans on the surface of eukaryotic cells, but also stimulates bacterial aggregation in response to divalent cations. Here we report the crystal structure of the Lcl C-terminal domain (Lcl-CTD) and present a model for intact Lcl. Our data reveal that Lcl-CTD forms an unusual trimer arrangement with a positively charged external surface and negatively charged solvent exposed internal cavity. Through molecular dynamics simulations, we show how the glycosaminoglycan chondroitin-4-sulphate associates with the Lcl-CTD surface via distinct binding modes. Our findings show that Lcl homologs are present across both the Pseudomonadota and Fibrobacterota-Chlorobiota-Bacteroidota phyla and suggest that Lcl may represent a versatile carbohydrate-binding mechanism.
摘要：
细菌粘附是使小生境环境定殖的基本过程,并且是感染的关键。然而,在嗜肺军团菌中，军团病的病原体，这些过程还没有得到很好的理解。军团菌胶原蛋白（Lcl）是一种细胞外外周膜蛋白，可识别真核细胞表面的硫酸化糖胺聚糖，但也刺激细菌聚集响应二价阳离子。在这里，我们报告了LclC末端结构域（Lcl-CTD）的晶体结构，并提出了完整Lcl的模型。我们的数据表明，Lcl-CTD形成了一种不寻常的三聚体排列，其带正电荷的外表面和带负电荷的溶剂暴露于内腔。通过分子动力学模拟,我们展示了糖胺聚糖-4-硫酸软骨素如何通过不同的结合模式与Lcl-CTD表面结合。我们的发现表明，Lcl同源物存在于Pseudomonadota和Fibrobacterota-Clobiota-Bacteroidota门，并表明Lcl可能代表一种通用的碳水化合物结合机制。
