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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Energetics and mechanisms of folding and flipping the myristoyl switch in the β-trefoil protein, hisactophilin
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Energetics and mechanisms of folding and flipping the myristoyl switch in the β-trefoil protein, hisactophilin

机译:β-三叶蛋白hisophilophilin中豆蔻酰开关折叠和翻转的能量学和机理

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摘要

Myristoylation, the covalent linkage of a saturated, C_(14) fatty acyl chain to the N-terminal glycine in a protein, plays a vital role in reversible membrane binding and signaling by the modified proteins. Currently, little is known about the effects of myristoylation on protein folding and stability, or about the energetics and molecular mechanisms of switching involving states with sequestered versus accessible myristoyl group. Our analysis of these effects in hisactophilin, a histidine-rich protein that binds cell membranes and actin in a pH-dependent manner, shows that myristoylation significantly increases hisactophilin stability, while also markedly increasing global protein folding and unfolding rates. The switching between sequestered and accessible states is pH dependent, with an apparent pK_(switch) of 6.95, and an apparent free energy change of 2.0 kcal-mol~(-1). The myristoyl switch is linked to the reversible uptake of ~1.5 protons, likely by histidine residues. This pH dependence of switching appears to be the physical basis of the sensitive, pH-dependent regulation of membrane binding observed in vivo. We conclude that an increase in protein stability upon modification and burial of the attached group is likely to occur in numerous proteins modified with fatty acyl or other hydro-phobic groups, and that the biophysical effects of such modification are likely to play an important role in their functional switches. In addition, the increased global dynamics caused by myristoylation of hisactophilin reveals a general mechanism whereby hydro-phobic moieties can make nonnative interactions or relieve strain in transition states, thereby increasing the rates of interconversion between different states.
机译:肉豆蔻酰基化是饱和的C_(14)脂肪酰基链与蛋白质N端甘氨酸的共价键,在修饰的蛋白质的可逆膜结合和信号传导中起着至关重要的作用。目前,关于肉豆蔻酰基化对蛋白质折叠和稳定性的影响,或者关于涉及具有螯合的肉豆蔻酰基与可接近的肉豆蔻酰基基团的状态的转换的能量学和分子机制知之甚少。我们对组织亲脂蛋白(一种富含组氨酸的蛋白,以pH依赖性方式结合细胞膜和肌动蛋白)中这些作用的分析表明,肉豆蔻酰化显着提高了组织亲脂蛋白的稳定性,同时还显着提高了整体蛋白折叠和解折叠速率。螯合状态和可及状态之间的切换取决于pH,表观pK_(switch)为6.95,表观自由能变化为2.0 kcal-mol〜(-1)。肉豆蔻酰开关与〜1.5质子的可逆摄取有关,可能是组氨酸残基引起的。转换的这种pH依赖性似乎是体内观察到的敏感的,pH依赖性的膜结合调节的物理基础。我们得出的结论是,修饰和掩埋连接基团后,蛋白质稳定性可能会在许多用脂肪酰基或其他疏水基团修饰的蛋白质中发生,并且这种修饰的生物物理作用可能在其中发挥重要作用。他们的功能开关。另外,由组脂蛋白的肉豆蔻酰化作用引起的整体动力学的增加揭示了一种普遍的机制,其中疏水性部分可以在过渡态中产生非天然相互作用或缓解应变,从而提高了不同状态之间的相互转化率。

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  • 作者单位

    Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1;

    Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1,Nuclear Magnetic Resonance Centre, University of Guelph, Guelph, ON,Canada N1G 2W1;

    Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1;

    Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1,Institute of Technology Assessment, Massachusetts General Hospital,Harvard Medical School, Boston, MA 02114;

    Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    thermodynamic cycle; switch dynamics; switch energetics;

    机译:热力学循环切换动态;开关能量学;

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