Protein homocysteinylation: possible mechanism underlying pathological consequences of elevated homocysteine levels
Protein homocysteinylation: possible mechanism underlying pathological consequences of elevated homocysteine levels
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DOI：
10.1096/fasebj.13.15.2277
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发表时间：
1999-12-01
期刊：
影响因子：
4.8
通讯作者：
Jakubowski, H
中科院分区：
文献类型：
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作者：
Jakubowski, H
同型半胱氨酸硫内酯是一种环状硫酯，由某些氨酰-tRNA合成酶在编辑或校对反应中合成，阻止同型半胱氨酸翻译掺入蛋白质。虽然高半胱氨酸硫代内酯预期酰化蛋白质中的氨基，但实际上对硫代内酯的反应性一无所知。在这里，它表明，硫代内酯与蛋白质赖氨酸残基的反应在生理条件下是稳健的。在与同型半胱氨酸硫代内酯孵育的人血清中，蛋白质同型半胱氨酸化是可以用低至10 nM硫代内酯观察到的主要反应。单个蛋白质以与其赖氨酸含量成比例的速率同型半胱氨酸化。同型半胱氨酸化导致蛋白质损伤，表现为广泛修饰的蛋白质的多聚化和沉淀。同型半胱氨酰-tRNA合成酶和胰蛋白酶等模型酶被同型半胱氨酰化而失活，同型半胱氨酸向硫内酯的代谢转化、蛋白质同型半胱氨酰化以及由此产生的蛋白质损伤可能是Hey参与血管疾病病理过程的基础。
Homocysteine thiolactone, a cyclic thioester, is synthesized by certain aminoacyl-tRNA synthetases in editing or proofreading reactions that prevent translational incorporation of homocysteine into proteins. Although homocysteine thiolactone is expected to acylate amino groups in proteins, virtually nothing is known regarding reactivity of the thiolactone. Here it is shown that reactions of the thiolactone with protein lysine residues were robust under physiological conditions. In human serum incubated with homocysteine thiolactone, protein homocysteinylation was a major reaction that could be observed with as little as 10 nM thiolactone, Individual proteins were homocysteinylated at rates proportional to their lysine contents. Homocysteinylation led to protein damage, manifested as multimerization and precipitation of extensively modified proteins. Model enzymes, such as methionyl-tRNA synthetase and trypsin, were inactivated by homocysteinylation, Metabolic conversion of homocysteine to the thiolactone, protein homocysteinylation, and resulting protein damage may underlie involvement of Hey in the pathology of vascular disease.