From the Chair of Biomolecular NMR Spectroscopy, Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
the Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, Alberta T2N 1N4, Canada, and.
J Biol Chem. 2019 Apr 26;294(17):7098-7112. doi: 10.1074/jbc.RA119.007653. Epub 2019 Mar 13.
The Ser/Thr protein kinase ataxia telangiectasia mutated (ATM) plays an important role in the DNA damage response, signaling in response to redox signals, the control of metabolic processes, and mitochondrial homeostasis. ATM localizes to the nucleus and at the plasma membrane, mitochondria, peroxisomes, and other cytoplasmic vesicular structures. It has been shown that the C-terminal FATC domain of human ATM (hATMfatc) can interact with a range of membrane mimetics and may thereby act as a membrane-anchoring unit. Here, NMR structural and N relaxation data, NMR data using spin-labeled micelles, and MD simulations of micelle-associated hATMfatc revealed that it binds the micelle by a dynamic assembly of three helices with many residues of hATMfatc located in the headgroup region. We observed that none of the three helices penetrates the micelle deeply or makes significant tertiary contacts to the other helices. NMR-monitored interaction experiments with hATMfatc variants in which two conserved aromatic residues (Phe and Trp) were either individually or both replaced by alanine disclosed that the double substitution does not abrogate the interaction with micelles and bicelles at the high concentrations at which these aggregates are typically used, but impairs interactions with small unilamellar vesicles, usually used at much lower lipid concentrations and considered a better mimetic for natural membranes. We conclude that the observed dynamic structure of micelle-associated hATMfatc may enable it to interact with differently composed membranes or membrane-associated interaction partners and thereby regulate ATM's kinase activity. Moreover, the FATC domain of ATM may function as a membrane-anchoring unit for other biomolecules.
丝氨酸/苏氨酸蛋白激酶共济失调毛细血管扩张突变（ATM）在 DNA 损伤反应、氧化还原信号转导、代谢过程控制和线粒体稳态中发挥重要作用。ATM 定位于细胞核和质膜、线粒体、过氧化物酶体和其他细胞质囊泡结构。已经表明，人 ATM 的 C 端 FATC 结构域（hATMfatc）可以与一系列膜模拟物相互作用，因此可能充当膜锚定单元。在这里，NMR 结构和 N 弛豫数据、使用自旋标记胶束的 NMR 数据以及胶束相关 hATMfatc 的 MD 模拟表明，它通过三个螺旋的动态组装与胶束结合，hATMfatc 的许多残基位于头部区域。我们观察到，这三个螺旋都没有深入穿透胶束，也没有与其他螺旋形成显著的三级接触。用 hATMfatc 变体进行的 NMR 监测相互作用实验中，两个保守的芳香族残基（苯丙氨酸和色氨酸）单独或同时被丙氨酸取代，结果表明，双取代不会在这些聚集物通常使用的高浓度下消除与胶束和双胶束的相互作用，但会损害与小单层囊泡的相互作用，小单层囊泡通常在低得多的脂质浓度下使用，并被认为是天然膜的更好模拟物。我们得出结论，观察到的胶束相关 hATMfatc 的动态结构可能使其能够与不同组成的膜或膜相关的相互作用伙伴相互作用，从而调节 ATM 的激酶活性。此外，ATM 的 FATC 结构域可能作为其他生物分子的膜锚定单元发挥作用。
