磷酸化模拟人细胞质支链转氨酶的晶体结构

IF 3.8 3区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Archives of biochemistry and biophysics Pub Date : 2025-05-23 DOI:10.1016/j.abb.2025.110479

Elizabeth S. Dare , Robert H. Newman , Myra E. Conway , Ming Dong

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引用次数: 0

摘要

绘制了丝裂原活化蛋白激酶(MAPK)/细胞外信号调节激酶2 （ERK2，也称为MAPK1）介导的人细胞质支链氨基转移酶（hBCATc）的磷酸化位点。测定了T33和T36位点磷酸化模拟物的晶体结构。对这些变异的转氨酶活性进行了分析。虽然在hBCAT的磷酸化模拟中没有主要的构象变化，但主要在突变体T33E中观察到域间环的区域构象变化。同样，当T33E和T36E突变体的催化转化率与野生型hBCATc相当时，KM比野生型显著下降，表明突变体的底物结合亲和力发生了变化。综上所述，这表明ERK2对hBCATc的磷酸化影响了hBCATc的转氨酶活性。

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Crystal structures of the phosphorylation mimics of human cytosolic branched chain aminotransferase

The phosphorylation sites of the human cytosolic Branched Chain Aminotransferase (hBCATc) mediated by mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated-kinase 2 (ERK2, also known as MAPK1) were mapped. The crystal structures of the phosphorylation mimics at T33 and T36 were determined. The modified transaminase activity of these variants was analyzed. Although there were no major conformational changes in the phosphorylation mimics of hBCAT, a regional conformational change at the interdomain loop was observed mainly in mutant T33E. Consistently, when the catalytic turnovers of the T33E and T36E mutants were comparable to the wild type of hBCATc, the K_M dropped significantly compared to the wild type, indicating a shift of the substrate binding affinity in the mutants. Taken together, this indicated the phosphorylation of hBCATc by ERK2 is affecting the hBCATc's transaminase activity.

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来源期刊

Archives of biochemistry and biophysics 生物-生化与分子生物学

CiteScore

7.40

自引率

0.00%

发文量

245

审稿时长

26 days

期刊介绍： Archives of Biochemistry and Biophysics publishes quality original articles and reviews in the developing areas of biochemistry and biophysics. Research Areas Include: • Enzyme and protein structure, function, regulation. Folding, turnover, and post-translational processing • Biological oxidations, free radical reactions, redox signaling, oxygenases, P450 reactions • Signal transduction, receptors, membrane transport, intracellular signals. Cellular and integrated metabolism.