Molecular Interfaces of the Galactose-binding Protein Tectonin Domains in Host-Pathogen Interaction*
Molecular Interfaces of the Galactose-binding Protein Tectonin Domains in Host-Pathogen Interaction*
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宿主-病原体相互作用中半乳糖结合蛋白 Tectonin 结构域的分子界面*
DOI：
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发表时间：
2010
影响因子：
4.8
通讯作者：
J. Ding
中科院分区：
文献类型：
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作者：
Diana Hooi Ping Low;V. Frecer;A. Le Saux;G. Srinivasan;B. Ho;Jianzhu Chen;J. Ding
β-螺旋桨蛋白在催化、蛋白质-蛋白质相互作用、细胞周期调节和先天免疫中发挥作用。半乳糖结合蛋白（GBP）是圆尾蟹血浆中的一种β螺旋桨蛋白，具有抗菌防御功能。研究表明，在与革兰氏阴性细菌脂多糖（LPS）结合后，GBP与C反应蛋白（CRP）相互作用，形成病原体识别复合物，有助于消除入侵的微生物。然而，GBP和LPS之间相互作用的分子基础以及它如何与CRP相互作用仍然是未知的。通过同源模建，我们发现GBP含有6个β-螺旋桨/Tectonin结构域。配体对接表明Tectonin结构域6至1可能含有LPS结合位点。蛋白质-蛋白质相互作用研究表明，Tectonin结构域4与CRP的相互作用最强。氢-氘交换质谱法绘制了GBP与LPS和CRP相互作用的不同位点，与计算机预测一致。此外，感染条件（降低的Ca 2+水平）使GBP-CRP亲和力增加1000倍。用生理水平的Ca 2+重新补充系统并没有逆转蛋白质-蛋白质亲和力到基础状态，这表明感染诱导的复合物发生了不可逆的构象变化。我们认为GBP作为一个桥接分子，参与了分子间的相互作用，GBP-LPS和GBP-CRP，形成一个稳定的病原体识别复合物。这两个合作伙伴的相互作用界面表明，Tectonin结构域可以区分自我/非自我，这对对抗感染的前线防御至关重要。此外，GBP与人类蛋白质hTectonin在结构和功能上具有同源性，这表明它在从马蹄蟹到人类的进化过程中保守了15亿年。
β-Propeller proteins function in catalysis, protein-protein interaction, cell cycle regulation, and innate immunity. The galactose-binding protein (GBP) from the plasma of the horseshoe crab, Carcinoscorpius rotundicauda, is a β-propeller protein that functions in antimicrobial defense. Studies have shown that upon binding to Gram-negative bacterial lipopolysaccharide (LPS), GBP interacts with C-reactive protein (CRP) to form a pathogen-recognition complex, which helps to eliminate invading microbes. However, the molecular basis of interactions between GBP and LPS and how it interplays with CRP remain largely unknown. By homology modeling, we showed that GBP contains six β-propeller/Tectonin domains. Ligand docking indicated that Tectonin domains 6 to 1 likely contain the LPS binding sites. Protein-protein interaction studies demonstrated that Tectonin domain 4 interacts most strongly with CRP. Hydrogen-deuterium exchange mass spectrometry mapped distinct sites of GBP that interact with LPS and with CRP, consistent with in silico predictions. Furthermore, infection condition (lowered Ca2+ level) increases GBP-CRP affinity by 1000-fold. Resupplementing the system with a physiological level of Ca2+ did not reverse the protein-protein affinity to the basal state, suggesting that the infection-induced complex had undergone irreversible conformational change. We propose that GBP serves as a bridging molecule, participating in molecular interactions, GBP-LPS and GBP-CRP, to form a stable pathogen-recognition complex. The interaction interfaces in these two partners suggest that Tectonin domains can differentiate self/nonself, crucial to frontline defense against infection. In addition, GBP shares architectural and functional homologies to a human protein, hTectonin, suggesting its evolutionarily conservation for ∼500 million years, from horseshoe crab to human.
影响因子：
7.4
作者：
Mandell, JG;Falick, AM;Komives, EA
通讯作者：
Komives, EA
影响因子：
3.1
作者：
Maguire, Michael E.
通讯作者：
Maguire, Michael E.