Wang Huanchen, Godage Himali Y, Riley Andrew M, Weaver Jeremy D, Shears Stephen B, Potter Barry V L
Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Wolfson Laboratory of Medicinal Chemistry, Department of Pharmacy and Pharmacology, University of Bath, Bath, Somerset BA2 7AY, UK.
Chem Biol. 2014 May 22;21(5):689-99. doi: 10.1016/j.chembiol.2014.03.009. Epub 2014 Apr 24.
Diphosphoinositol pentakisphosphate kinase 2 (PPIP5K2) is one of the mammalian PPIP5K isoforms responsible for synthesis of diphosphoinositol polyphosphates (inositol pyrophosphates; PP-InsPs), regulatory molecules that function at the interface of cell signaling and organismic homeostasis. The development of drugs that inhibit PPIP5K2 could have both experimental and therapeutic applications. Here, we describe a synthetic strategy for producing naturally occurring 5-PP-InsP4, as well as several inositol polyphosphate analogs, and we study their interactions with PPIP5K2 using biochemical and structural approaches. These experiments uncover an additional ligand-binding site on the surface of PPIP5K2, adjacent to the catalytic pocket. This site facilitates substrate capture from the bulk phase, prior to transfer into the catalytic pocket. In addition to demonstrating a "catch-and-pass" reaction mechanism in a small molecule kinase, we demonstrate that binding of our analogs to the substrate capture site inhibits PPIP5K2. This work suggests that the substrate-binding site offers new opportunities for targeted drug design.
二磷酸肌醇五磷酸激酶2（PPIP5K2）是负责合成二磷酸肌醇多磷酸（肌醇焦磷酸；PP-InsPs）的哺乳动物PPIP5K亚型之一，PP-InsPs是在细胞信号传导和机体稳态界面发挥作用的调节分子。抑制PPIP5K2的药物开发可能具有实验和治疗应用价值。在此，我们描述了一种合成策略，用于制备天然存在的5-PP-InsP4以及几种肌醇多磷酸类似物，并使用生化和结构方法研究它们与PPIP5K2的相互作用。这些实验揭示了PPIP5K2表面上与催化口袋相邻的一个额外的配体结合位点。该位点有助于在底物转移到催化口袋之前从本体相中捕获底物。除了在小分子激酶中证明“捕获并传递”反应机制外，我们还证明我们的类似物与底物捕获位点的结合会抑制PPIP5K2。这项工作表明底物结合位点为靶向药物设计提供了新的机会。
