Regulation of mitochondrial carbamoyl-phosphate synthetase 1 activity by active site fatty acylation
Regulation of mitochondrial carbamoyl-phosphate synthetase 1 activity by active site fatty acylation
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DOI：
10.1074/jbc.m102766200
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发表时间：
2001-12-07
影响因子：
4.8
通讯作者：
Berthiaume, LG
中科院分区：
文献类型：
--
作者：
Corvi, MM;Soltys, CLM;Berthiaume, LG
除了在信号转导蛋白的可逆膜定位中发挥作用外，蛋白质脂肪酰化还可以在线粒体代谢的调节中发挥作用。先前的研究表明，从 COS-7 细胞和大鼠肝脏中分离的线粒体中存在多种酰化蛋白。在这里，来自大鼠肝线粒体的一种重要的脂肪酰化 165 kDa 蛋白质被鉴定为氨基甲酰磷酸合成酶 1 (CPS 1)。共价连接的棕榈酸酯通过硫酯键与 CPS 1 连接，导致在生理浓度的棕榈酰辅酶 A 下抑制 CPS I 活性。这种抑制对应于 CPS 1 的不可逆失活，并以时间和浓度依赖性方式发生。通过与 N-乙基马来酰亚胺和 5'-对氟磺酰基苯甲酰基腺苷（一种与 CPS 1 活性位点半胱氨酸残基反应的 ATP 类似物）预孵育可防止 CPS 1 的脂肪酰化。我们的结果表明，CPS 1 的脂肪酰化对长链脂肪酰辅酶 A 具有特异性，并且很可能发生在至少一个抑制 CPS 1 催化活性的必需半胱氨酸残基上。长链脂肪酰辅酶 A 抑制 CPS 1 可以减少氨基酸降解和尿素分泌，从而有助于饥饿期间的氮节约。
In addition to its role in reversible membrane localization of signal-transducing proteins, protein fatty acylation could play a role in the regulation of mitochondrial metabolism. Previous studies have shown that several acylated proteins exist in mitochondria isolated from COS-7 cells and rat liver. Here, a prominent fatty-acylated 165-kDa protein from rat liver mitochondria was identified as carbamoyl-phosphate synthetase 1 (CPS 1). Covalently attached palmitate was linked to CPS 1 via a thioester bond resulting in an inhibition of CPS I activity at physiological concentrations of palmitoyl-CoA. This inhibition corresponds to irreversible inactivation of CPS 1 and occurred in a time- and concentration-dependent manner. Fatty acylation of CPS 1 was prevented by preincubation with N-ethylmaleimide and 5'-p-fluorosulfonylbenzoyladenosine, an ATP analog that reacts with CPS 1 active site cysteine residues. Our results suggest that fatty acylation of CPS 1 is specific for long-chain fatty acyl-CoA and very likely occurs on at least one of the essential cysteine residues inhibiting the catalytic activity of CPS 1. Inhibition of CPS 1 by long-chain fatty acyl-CoAs could reduce amino acid degradation and urea secretion, thereby contributing to nitrogen sparing during starvation.