Nitration of a critical tyrosine residue in the allosteric inhibitor site of muscle glycogen phosphorylase impairs its catalytic activity
Nitration of a critical tyrosine residue in the allosteric inhibitor site of muscle glycogen phosphorylase impairs its catalytic activity
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DOI：
10.1016/j.jmb.2007.07.011
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发表时间：
2007-09-28
影响因子：
5.6
通讯作者：
Rodrigues-Lima, Fernando
中科院分区：
文献类型：
--
作者：
Dairou, Julien;Pluvinage, Benjamin;Rodrigues-Lima, Fernando
肌糖原磷酸化酶（GP）是葡萄糖代谢的关键酶，其损伤可导致肌肉功能障碍。糖原磷酸化酶的酪氨酸硝化发生在衰老过程中，并已被认为与肌肉性能的进行性丧失有关。在这里，我们表明，GP（在其T和R形式）是不可逆的受损暴露于过氧亚硝酸盐，已知硝酸盐反应性酪氨酸残基的生物氮物种，并参与生理和病理过程。动力学和生物化学分析表明，过亚硝酸根对GP的不可逆失活是由于酶的一个独特的酪氨酸残基的快速硝化（k（inact）= 3 × 10（4）M-1 S-1）。内源性GP酪氨酸硝化和不可逆失活骨骼肌细胞暴露于过氧亚硝酸盐后，伴随损害糖原动员。使用纯化的GP的配体保护测定和质谱分析表明，过氧亚硝酸盐依赖性失活的酶可能是由于硝化的Tyr 613，一个关键的氨基酸的变构抑制剂位点的酶。我们的研究结果表明，GP功能可能是受酪氨酸硝化。(c)2007爱思唯尔有限公司保留所有权利。
Muscle glycogen phosphorylase (GP) is a key enzyme in glucose metabolism, and its impairment can lead to muscle dysfunction. Tyrosine nitration of glycogen phosphorylase occurs during aging and has been suggested to be involved in progressive loss of muscle performance. Here, we show that GP (in its T and R form) is irreversibly impaired by exposure to peroxynitrite, a biological nitrogen species known to nitrate reactive tyrosine residues, and to be involved in physiological and pathological processes. Kinetic and biochemical analysis indicated that irreversible inactivation of GP by peroxynitrite is due to the fast (k(inact) = 3 x 10(4) M-1 S-1) nitration of a unique tyrosine residue of the Enzyme. Endogenous GP was tyrosine nitrated and irreversibly inactivated in skeletal muscle cells upon exposure to peroxynitrite, with concomitant impairment of glycogen mobilization. Ligand protection assays and mass spectrometry analysis using purified GP suggested that the peroxynitrite-dependent inactivation of the enzyme could be due to the nitration of Tyr613, a key amino acid of the allosteric inhibitor site of the enzyme. Our findings suggest that GP functions may be regulated by tyrosine nitration. (c) 2007 Elsevier Ltd. All rights reserved.