Shimada Atsushi, Niwa Hideaki, Tsujita Kazuya, Suetsugu Shiro, Nitta Koji, Hanawa-Suetsugu Kyoko, Akasaka Ryogo, Nishino Yuri, Toyama Mitsutoshi, Chen Lirong, Liu Zhi-Jie, Wang Bi-Cheng, Yamamoto Masaki, Terada Takaho, Miyazawa Atsuo, Tanaka Akiko, Sugano Sumio, Shirouzu Mikako, Nagayama Kuniaki, Takenawa Tadaomi, Yokoyama Shigeyuki
RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
Cell. 2007 May 18;129(4):761-72. doi: 10.1016/j.cell.2007.03.040.
Pombe Cdc15 homology (PCH) proteins play an important role in a variety of actin-based processes, including clathrin-mediated endocytosis (CME). The defining feature of the PCH proteins is an evolutionarily conserved EFC/F-BAR domain for membrane association and tubulation. In the present study, we solved the crystal structures of the EFC domains of human FBP17 and CIP4. The structures revealed a gently curved helical-bundle dimer of approximately 220 A in length, which forms filaments through end-to-end interactions in the crystals. The curved EFC dimer fits a tubular membrane with an approximately 600 A diameter. We subsequently proposed a model in which the curved EFC filament drives tubulation. In fact, striation of tubular membranes was observed by phase-contrast cryo-transmission electron microscopy, and mutations that impaired filament formation also impaired membrane tubulation and cell membrane invagination. Furthermore, FBP17 is recruited to clathrin-coated pits in the late stage of CME, indicating its physiological role.
粟酒裂殖酵母Cdc15同源（PCH）蛋白在多种基于肌动蛋白的过程中发挥重要作用，包括网格蛋白介导的内吞作用（CME）。PCH蛋白的决定性特征是一个用于膜结合和微管形成的进化上保守的EFC/F-BAR结构域。在本研究中，我们解析了人类FBP17和CIP4的EFC结构域的晶体结构。这些结构揭示了一个长度约为220 Å的轻微弯曲的螺旋束二聚体，其在晶体中通过端对端相互作用形成细丝。弯曲的EFC二聚体适合直径约为600 Å的管状膜。我们随后提出了一个模型，其中弯曲的EFC细丝驱动微管形成。事实上，通过相差冷冻透射电子显微镜观察到了管状膜的条纹，并且损害细丝形成的突变也损害了膜微管形成和细胞膜内陷。此外，FBP17在CME后期被募集到网格蛋白包被小窝，表明了其生理作用。
