Heuer Katja, Sylvester Marc, Kliche Stefanie, Pusch Rico, Thiemke Katharina, Schraven Burkhart, Freund Christian
Protein Engineering Group, Leibniz Institute of Molecular Pharmacology and Freie Universität Berlin, Germany.
J Mol Biol. 2006 Aug 4;361(1):94-104. doi: 10.1016/j.jmb.2006.06.004. Epub 2006 Jun 19.
SH3 domains represent versatile scaffolds within eukaryotic cells by targeting proline-rich sequences within intracellular proteins. More recently, binding of SH3 domains to unusual peptide motifs, folded proteins or lipids has been reported. Here we show that the newly defined hSH3 domains of immune cell adapter proteins bind lipid membranes with distinct affinities. The interaction of the hSH3 domains of adhesion and degranulation promoting adapter protein (ADAP) and PRAM-1 (Promyelocytic-Retinoic acid receptor alpha target gene encoding an Adaptor Molecule-1), with phosphatidylcholine-containing liposomes is observed upon incorporation of phosphatidylserine (PS) or phosphoinositides (PIs) into the membrane bilayer. Mechanistically we show that stable association of the N-terminal, amphipathic helix with the beta-sheet scaffold favours lipid binding and that the interaction with PI(4,5)P(2)-containing liposomes is consistent with a single-site, non-cooperative binding mechanism. Functional investigations indicate that deletion of both amphipathic helices of the hSH3 domains reduces the ability of ADAP to enhance adhesion and migration in stimulated T cells.
SH3结构域通过靶向细胞内蛋白质中富含脯氨酸的序列，在真核细胞中代表多功能支架。最近，有报道称SH3结构域与异常肽基序、折叠蛋白或脂质结合。在这里，我们表明免疫细胞衔接蛋白新定义的hSH3结构域以不同的亲和力结合脂质膜。当磷脂酰丝氨酸（PS）或磷酸肌醇（PIs）掺入膜双层时，观察到促进黏附与脱颗粒衔接蛋白（ADAP）和PRAM-1（早幼粒细胞维甲酸受体α靶基因，编码衔接分子1）的hSH3结构域与含磷脂酰胆碱的脂质体相互作用。从机制上我们表明，N端两亲性螺旋与β折叠支架的稳定结合有利于脂质结合，并且与含PI(4,5)P(2)的脂质体的相互作用符合单位点、非协同结合机制。功能研究表明，hSH3结构域的两个两亲性螺旋缺失会降低ADAP增强刺激的T细胞黏附和迁移的能力。
