Tsujishita Y, Guo S, Stolz L E, York J D, Hurley J H
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, , Bethesda, MD 20892, USA.
Cell. 2001 May 4;105(3):379-89. doi: 10.1016/s0092-8674(01)00326-9.
Inositol polyphosphate 5-phosphatases are central to intracellular processes ranging from membrane trafficking to Ca(2+) signaling, and defects in this activity result in the human disease Lowe syndrome. The 1.8 resolution structure of the inositol polyphosphate 5-phosphatase domain of SPsynaptojanin bound to Ca(2+) and inositol (1,4)-bisphosphate reveals a fold and an active site His and Asp pair resembling those of several Mg(2+)-dependent nucleases. Additional loops mediate specific inositol polyphosphate contacts. The 4-phosphate of inositol (1,4)-bisphosphate is misoriented by 4.6 compared to the reactive geometry observed in the apurinic/apyrimidinic endonuclease 1, explaining the dephosphorylation site selectivity of the 5-phosphatases. Based on the structure, a series of mutants are described that exhibit altered substrate specificity providing general determinants for substrate recognition.
肌醇多磷酸5-磷酸酶在从膜运输到Ca(2+)信号传导的细胞内过程中起着核心作用，这种活性的缺陷会导致人类疾病洛氏综合征。与Ca(2+)和肌醇(1,4)-二磷酸结合的突触素肌醇多磷酸5-磷酸酶结构域的1.8埃分辨率结构揭示了一种折叠以及一个活性位点组氨酸和天冬氨酸对，类似于几种Mg(2+)-依赖性核酸酶。额外的环介导特定的肌醇多磷酸接触。与无嘌呤/无嘧啶内切核酸酶1中观察到的反应几何结构相比，肌醇(1,4)-二磷酸的4-磷酸错位了4.6埃，这解释了5-磷酸酶的去磷酸化位点选择性。基于该结构，描述了一系列表现出改变的底物特异性的突变体，为底物识别提供了一般决定因素。
