The mechanisms underlying the GPCR-mediated chemotaxis in D. discoideum

如何专业吞噬细胞，D。一种新的MAMP受体的发现 社会阿米巴D.盘状体是通过趋化性捕获细菌并通过吞噬作用将它们作为食物吞噬的专职吞噬细胞。 虽然细菌释放的叶酸是D. discoideum寻找细菌超过40年前，叶酸受体还没有被确定。 使用定量磷蛋白质组学技术，我们发现孤儿GPCR fAR 1介导对叶酸的趋化性以追逐细菌，并在革兰氏菌的吞噬作用中发挥作用（Pan et al. Dev Cell，2016）。 我们发现，fAR 1同时识别化学引诱物叶酸和吞噬提示脂多糖（LPS），细菌表面的主要成分。 我们的计算模拟与实验相结合表明，与趋化性相关的反应也可以促进包裹有化学引诱剂的颗粒的吞噬。 最后，fAR 1的细胞外捕蝇草结构域作为叶酸和脂多糖的结合位点。因此，fAR 1代表模式识别受体的新成员，并介导来自细菌表面和可扩散化学引诱物的信号传导，以重组肌动蛋白用于趋化性和吞噬作用（Pan et al PLOS Biology，2018）。 我们正试图确定革兰氏阳性菌的其他表面分子的受体。

How professional phagocytes, D. discoideum, chase and recognize various bacteria as food-The discovery of a new MAMP receptor The social amoeba D. discoideum is a professional phagocyte that catches bacteria via chemotaxis and engulf them as food via phagocytosis. Although folic acid released by bacteria was shown to be the chemoattractant for D. discoideum to seek bacteria more than 40 years ago, a folic acid receptor had not been identified. Using a quantitative phosphor-proteomic technique, we find that an orphan GPCR, fAR1, mediates chemotaxis toward folate to chase bacteria and plays a role in the phagocytosis of Gram- bacteria (Pan et al. Dev Cell, 2016). We show that fAR1 simultaneously recognizes the chemoattractant folate and the phagocytic cue lipopolysaccharide (LPS), a major component of bacterial surfaces. Our computational simulations combined with experiments show that responses associated with chemotaxis can also promote engulfment of particles coated with chemoattractants. Finally, the extracellular Venus-Flytrap domain of fAR1 acts as the binding site for both folate and lipopolysaccharide. Thus, fAR1 represents a new member of the pattern recognition receptors and mediates signaling from both bacterial surfaces and diffusible chemoattractants to reorganize actin for chemotaxis and phagocytosis (Pan et al PLOS Biology, 2018). We are trying to identify receptors for other surface molecules of Gram+ bacteria.