The crystal structure of mammalian inositol 1,3,4,5,6-pentakisphosphate 2-kinase reveals a new zinc-binding site and key features for protein function.
The crystal structure of mammalian inositol 1,3,4,5,6-pentakisphosphate 2-kinase reveals a new zinc-binding site and key features for protein function.
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DOI：
10.1074/jbc.m117.780395
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发表时间：
2017-06-23
期刊：
影响因子：
--
通讯作者：
González B
中科院分区：
文献类型：
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作者：
Franco-Echevarría E;Sanz-Aparicio J;Brearley CA;González-Rubio JM;González B
肌醇1,3,4,5,6-五磷酸二激酶（IP5 2-Ks）是真核细胞中负责合成六磷酸肌醇（IP6）的酶家族的一部分。该蛋白及其产物IP6在细胞中发挥多种作用，参与mRNA输出、胚胎发育和细胞凋亡。我们以前报道过，拟南芥全长IP5 2-K是一个锌金属酶，包括两个分离的裂片（N-裂片和c -裂片）。我们还展示了IP5 2-K的构象变化，并确定了参与底物识别和催化的残基。然而，哺乳动物IP5 2-Ks的具体特征尚不清楚。为此，我们在此报告了小鼠IP5 2-K与ATP/IP5或IP6复合物的第一个结构。我们的结构发现表明，拟南藓的N-叶和c -叶的一般折叠在IP5 2-K中是保守的。c叶中的螺旋支架构成肌醇磷酸结合位点，与n叶的参与一起，赋予该蛋白高特异性。然而，我们也注意到这两个真核生物王国的同源物之间存在巨大的结构差异。这些差异包括一个新的锌结合位点和哺乳动物IP5 2-K特有的区域，作为蛋白质表面的一个意想不到的基本斑块。总之，我们的发现揭示了哺乳动物IP5 2-K的独特特征，并为研究蛋白质-蛋白质或蛋白质- rna相互作用对IP5 2-K功能和活性的重要作用奠定了基础。
Inositol 1,3,4,5,6-pentakisphosphate 2-kinases (IP5 2-Ks) are part of a family of enzymes in charge of synthesizing inositol hexakisphosphate (IP6) in eukaryotic cells. This protein and its product IP6 present many roles in cells, participating in mRNA export, embryonic development, and apoptosis. We reported previously that the full-length IP5 2-K from Arabidopsis thaliana is a zinc metallo-enzyme, including two separated lobes (the N- and C-lobes). We have also shown conformational changes in IP5 2-K and have identified the residues involved in substrate recognition and catalysis. However, the specific features of mammalian IP5 2-Ks remain unknown. To this end, we report here the first structure for a murine IP5 2-K in complex with ATP/IP5 or IP6. Our structural findings indicated that the general folding in N- and C-lobes is conserved with A. thaliana IP5 2-K. A helical scaffold in the C-lobe constitutes the inositol phosphate-binding site, which, along with the participation of the N-lobe, endows high specificity to this protein. However, we also noted large structural differences between the orthologues from these two eukaryotic kingdoms. These differences include a novel zinc-binding site and regions unique to the mammalian IP5 2-K, as an unexpected basic patch on the protein surface. In conclusion, our findings have uncovered distinct features of a mammalian IP5 2-K and set the stage for investigations into protein-protein or protein-RNA interactions important for IP5 2-K function and activity.