Del Campo Claudia M, Mishra Ashwini K, Wang Yu-Hsiu, Roy Craig R, Janmey Paul A, Lambright David G
Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Institute for Medicine and Engineering and Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
Structure. 2014 Mar 4;22(3):397-408. doi: 10.1016/j.str.2013.12.018. Epub 2014 Feb 13.
Recruitment of the Legionella pneumophila effector DrrA to the Legionella-containing vacuole, where it activates and AMPylates Rab1, is mediated by a P4M domain that binds phosphatidylinositol 4-phosphate [PI(4)P] with high affinity and specificity. Despite the importance of PI(4)P in Golgi trafficking and its manipulation by pathogens, the structural bases for PI(4)P-dependent membrane recruitment remain poorly defined. Here, we determined the crystal structure of a DrrA fragment including the P4M domain in complex with dibutyl PI(4)P and investigated the determinants of phosphoinositide recognition and membrane targeting. Headgroup recognition involves an elaborate network of direct and water-mediated interactions with basic and polar residues in the context of a deep, constrictive binding pocket. An adjacent hydrophobic helical element packs against the acyl chains and inserts robustly into PI(4)P-containing monolayers. The structural, biochemical, and biophysical data reported here support a detailed structural mechanism for PI(4)P-dependent membrane targeting by DrrA.
嗜肺军团菌效应蛋白DrrA被招募到含军团菌的液泡中，在那里它激活Rab1并使其腺苷酸化，这一过程由一个P4M结构域介导，该结构域能以高亲和力和特异性结合磷脂酰肌醇4-磷酸[PI(4)P]。尽管PI(4)P在高尔基体运输中很重要且会被病原体操纵，但其依赖PI(4)P的膜招募的结构基础仍不清楚。在这里，我们确定了一个包含P4M结构域的DrrA片段与二丁基PI(4)P复合物的晶体结构，并研究了磷酸肌醇识别和膜靶向的决定因素。头部基团识别涉及在一个深的、狭窄的结合口袋中与碱性和极性残基的直接和水介导相互作用的复杂网络。一个相邻的疏水螺旋元件靠在酰基链上，并牢固地插入含PI(4)P的单层膜中。本文报道的结构、生化和生物物理数据支持了DrrA依赖PI(4)P的膜靶向的详细结构机制。
