Kraushaar Timo, Brückner Stefan, Veelders Maik, Rhinow Daniel, Schreiner Franka, Birke Raphael, Pagenstecher Axel, Mösch Hans-Ulrich, Essen Lars-Oliver
Department of Chemistry, Philipps-Universität, Hans-Meerwein-Straße 4, 35032 Marburg, Germany; Department of Biology, Philipps-Universität, Karl-von-Frisch-Straße 8, 35043 Marburg, Germany.
Department of Biology, Philipps-Universität, Karl-von-Frisch-Straße 8, 35043 Marburg, Germany.
Structure. 2015 Jun 2;23(6):1005-17. doi: 10.1016/j.str.2015.03.021. Epub 2015 May 7.
Saccharomyces cerevisiae harbors a family of GPI-anchored cell wall proteins for interaction with its environment. The flocculin Flo11, a major representative of these fungal adhesins, confers formation of different types of multicellular structures such as biofilms, flors, or filaments. To understand these environment-dependent growth phenotypes on a molecular level, we solved the crystal structure of the N-terminal Flo11A domain at 0.89-Å resolution. Besides a hydrophobic apical region, the Flo11A domain consists of a β sandwich of the fibronectin type III domain (FN3). We further show that homophilic Flo11-Flo11 interactions and heterophilic Flo11-plastic interactions solely depend on the Flo11A domain and are strongly pH dependent. These functions of Flo11A involve an apical region with its surface-exposed aromatic band, which is accompanied by acidic stretches. Together with electron microscopic reconstructions of yeast cell-cell contact sites, our data suggest that Flo11 acts as a spacer-like, pH-sensitive adhesin that resembles a membrane-tethered hydrophobin.
酿酒酵母含有一类糖基磷脂酰肌醇（GPI）锚定的细胞壁蛋白，用于与周围环境相互作用。絮凝蛋白Flo11是这些真菌粘附素的主要代表，它能促使形成不同类型的多细胞结构，如生物膜、菌花或菌丝。为了在分子水平上理解这些依赖环境的生长表型，我们以0.89埃的分辨率解析了N端Flo11A结构域的晶体结构。除了一个疏水的顶端区域外，Flo11A结构域由一个纤连蛋白III型结构域（FN3）的β三明治组成。我们进一步表明，Flo11-Flo11的同源相互作用和Flo11-塑料的异源相互作用仅取决于Flo11A结构域，并且强烈依赖于pH值。Flo11A的这些功能涉及一个顶端区域及其表面暴露的芳香带，该区域伴有酸性片段。结合酵母细胞间接触位点的电子显微镜重建，我们的数据表明Flo11作为一种类似间隔物的、pH敏感的粘附素，类似于膜锚定的疏水蛋白。
