β-Subunit myristoylation is the gatekeeper for initiating metabolic stress sensing by AMP-activated protein kinase (AMPK)
β-Subunit myristoylation is the gatekeeper for initiating metabolic stress sensing by AMP-activated protein kinase (AMPK)
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DOI：
10.1073/pnas.1009705107
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发表时间：
2010-11-09
影响因子：
11.1
通讯作者：
Kemp, Bruce E.
中科院分区：
文献类型：
--
作者：
Oakhill, Jonathan S.;Chen, Zhi-Ping;Kemp, Bruce E.
AMP激活的蛋白激酶（AMPK）是α β γ异源三聚体，其充当主代谢调节剂以在能量需求增加和AMP/ATP比率增加后维持细胞能量平衡。这种调节提供了能量代谢的动态控制，使能量供应与生物体的功能和生存所必需的需求相匹配。AMPK是无活性的，除非在α-催化亚基活化环中的Thr 172上被上游激酶（LKB 1或钙-钙调蛋白依赖性蛋白激酶激酶β）磷酸化。AMP水平的升高如何触发AMPK α-Thr 172磷酸化和激活尚不完全清楚。在这里，我们明确地证明，AMP直接刺激α-Thr 172磷酸化提供的AMPK β亚基豆蔻酰化。肉豆蔻酰基团的丧失消除AMP活化并降低α-Thr 172磷酸化的程度。一旦AMPK被磷酸化，AMP进一步变构激活，但这种激活不需要β亚基肉豆蔻酰化。AMP和葡萄糖剥夺也促进肉豆蔻酰化AMPK的膜缔合，指示肉豆蔻酰转换机制。我们的研究结果表明，AMP调节AMPK激活在初始磷酸化步骤，β-亚基豆蔻酰化是重要的代谢应激信号转导。
The AMP-activated protein kinase (AMPK) is an alpha beta gamma heterotrimer that acts as a master metabolic regulator to maintain cellular energy balance following increased energy demand and increases in the AMP/ATP ratio. This regulation provides dynamic control of energy metabolism, matching energy supply with demand that is essential for the function and survival of organisms. AMPK is inactive unless phosphorylated on Thr172 in the alpha-catalytic subunit activation loop by upstream kinases (LKB1 or calcium-calmodulin-dependent protein kinase kinase beta). How a rise in AMP levels triggers AMPK alpha-Thr172 phosphorylation and activation is incompletely understood. Here we demonstrate unequivocally that AMP directly stimulates alpha-Thr172 phosphorylation provided the AMPK beta-subunit is myristoylated. Loss of the myristoyl group abolishes AMP activation and reduces the extent of alpha-Thr172 phosphorylation. Once AMPK is phosphorylated, AMP further activates allosterically but this activation does not require beta-subunit myristoylation. AMP and glucose deprivation also promote membrane association of myristoylated AMPK, indicative of a myristoyl-switch mechanism. Our results show that AMP regulates AMPK activation at the initial phosphorylation step, and that beta-subunit myristoylation is important for transducing the metabolic stress signal.