Dephosphorylation of 2,3-bisphosphoglycerate by MIPP expands the regulatory capacity of the Rapoport-Luebering glycolytic shunt
Dephosphorylation of 2,3-bisphosphoglycerate by MIPP expands the regulatory capacity of the Rapoport-Luebering glycolytic shunt
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DOI：
10.1073/pnas.0710980105
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发表时间：
2008-04-22
影响因子：
11.1
通讯作者：
Shears, Stephen B.
中科院分区：
文献类型：
--
作者：
Cho, Jaiesoon;King, Jason S.;Shears, Stephen B.
Rapoport-Luebering 糖酵解旁路包含进化上保守的反应，可生成 2,3-二磷酸甘油酸 (2,3-BPG) 并使其去磷酸化。 30 年来，这些反应一直被认为是由单一酶 2,3-BPG 合酶/2-磷酸酶 (BPGM) 负责。在这里，我们发现盘基网柄菌、鸟类和哺乳动物含有额外的 2,3-BPG 磷酸酶，与 BPGM 不同，它可以去除 3-磷酸。这一发现揭示了糖酵解途径可以绕过 3-磷酸甘油酸的形成，3-磷酸甘油酸是丝氨酸生物合成的前体和 AMP 激活蛋白激酶的激活剂。我们的 2,3-BPG 磷酸酶活性由先前鉴定的多种肌醇多磷酸磷酸酶 (MIPP11) 基因编码，现在我们证明该基因具有双底物特异性。通过对盘基网柄菌中的 Mlippl 表达进行基因操作，我们证明该酶对细胞 2,3-BPG 含量提供生理相关的调节。哺乳动物红细胞的 2,3-BPG 含量最高，它控制着氧与血红蛋白的结合。我们确定，37°C 下红细胞中的 MIPP11 总活性为每小时每升细胞水解 0.6 mmol 2,3-BPG，与之前发布的 BPGM 磷酸酶活性估计值相匹配。 MIPP11 在 4°C 时具有活性，这表明在输血储存红细胞期间，MIPP11 对 2,3-BPG 损失具有临床意义。人MIPP11水解2,3-BPG对生理性碱中毒敏感；当 pH 从 7.0 升至 7.4 时，活性降低 50%。这种现象提供了一种提高 2,3-BPG 水平的稳态机制，从而增强组织的氧气释放。我们的数据表明 Rapoport-Luebering 分流的生物学意义比之前认为的更大。
The Rapoport-Luebering glycolytic bypass comprises evolutionarily conserved reactions that generate and dephosphorylate 2,3-bisphosphoglycerate (2,3-BPG). For >30 years, these reactions have been considered the responsibility of a single enzyme, the 2,3-BPG synthase/2-phosphatase (BPGM). Here, we show that Dictyosteiium, birds, and mammals contain an additional 2,3-BPG phosphatase that, unlike BPGM, removes the 3-phosphate. This discovery reveals that the glycolytic pathway can bypass the formation of 3-phosphoglycerate, which is a precursor for serine biosynthesis and an activator of AMP-activated protein kinase. Our 2,3-BPG phosphatase activity is encoded by the previously identified gene for multiple inositol polyphosphate phosphatase (MIPP11), which we now show to have dual substrate specificity. By genetically manipulating Mlippl expression in Dictyostelium, we demonstrated that this enzyme provides physiologically relevant regulation of cellular 2,3-BPG content. Mammalian erythrocytes possess the highest content of 2,3-BPG, which controls oxygen binding to hemoglobin. We determined that total MIPP11 activity in erythrocytes at 37 degrees C is 0.6 mmol 2,3-BPG hydrolyzed per liter of cells per h, matching previously published estimates of the phosphatase activity of BPGM. MIPP11 is active at 4 degrees C, revealing a clinically significant contribution to 2,3-BPG loss during the storage of erythrocytes for transfusion. Hydrolysis of 2,3-BPG by human MIPP11 is sensitive to physiologic alkalosis; activity decreases 50% when pH rises from 7.0 to 7.4. This phenomenon provides a homeostatic mechanism for elevating 2,3-BPG levels, thereby enhancing oxygen release to tissues. our data indicate greater biological significance of the Rapoport-Luebering shunt than previously considered.