Apolipoprotein E4 has extensive conformational heterogeneity in lipid-free and lipid-bound forms.
Apolipoprotein E4 has extensive conformational heterogeneity in lipid-free and lipid-bound forms.
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DOI：
10.1073/pnas.2215371120
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发表时间：
2023-02-14
影响因子：
11.1
通讯作者：
Soranno, Andrea
中科院分区：
文献类型：
--
作者：
Stuchell-Brereton, Melissa D.;Zimmerman, Maxwell I.;Miller, Justin J.;Mallimadugula, Upasana L.;Incicco, J. Jeremias;Roy, Debjit;Smith, Louis G.;Cubuk, Jasmine;Baban, Berevan;DeKoster, Gregory T.;Frieden, Carl;Bowman, Gregory R.;Soranno, Andrea
尽管早在20多年前就被确定为阿尔茨海默病的最大遗传风险因素，但载脂蛋白E(ApoE)的生化特性与其在疾病中的作用之间的联系仍然难以捉摸。这在很大程度上是由于致病和非致病变异体中蛋白质采用的不同形式(单体、二聚体、四聚体和脂结合)的结构信息有限。在这里，我们提供了在存在和不存在脂类的情况下以单体形式的全长致病ApoE4的特征。我们证明，该蛋白质不是采用单一的结构，而是多种不同的构象，这影响了对载脂蛋白E结构-功能机制的解释。载脂蛋白E(ApoE4)的ε4等位基因变异是阿尔茨海默病最强的遗传风险因素，尽管它与其中性等位基因ApoE3只有一个氨基酸替代。虽然载脂蛋白E4影响斑块和神经原纤维缠结的形成，但由于结构信息有限，致病性的结构决定因素仍未确定。以前的研究已经导致了C-末端区域相对于N-末端结构域跨异构体定位的相互矛盾的模型，主要是因为数据可能被多相低聚物的存在所混淆。在这里，我们应用单分子光谱学和分子动力学模拟相结合的方法，构建了单体ApoE4的原子详细模型，并探讨了脂质缔合的影响。重要的是，我们的方法克服了以前的限制，允许我们在只有单体存在的皮摩尔浓度下工作。我们的数据显示，载脂蛋白E4比之前认为的更加无序和延长，并在结合脂类后保持了显著的构象异质性。比较三种主要异构体(ApoE4、ApoE3和APOE2)的N-末端和C-末端结构域的接近程度表明，所有异构体都以单体形式保持不同的构象，而APOE2采用了稍微更紧凑的系综。总体而言，这些数据为理解ApoE4与非致病性和保护性蛋白质变体的不同之处提供了基础。
Despite being identified as the strongest genetic risk factor for Alzheimer’s disease more than 20 years ago, a connection between the biochemical properties of apolipoprotein E (ApoE) and its role in the disease remains elusive. This is largely due to the limited structural information available for the different forms adopted by the protein (monomer, dimer, tetramer, and lipid bound) across pathogenic and nonpathogenic variants. Here, we provide the characterization of the full-length pathogenic ApoE4 in its monomeric form both in the presence and absence of lipids. We demonstrate that the protein does not adopt a single structure, but a multiplicity of different conformations, which impacts the interpretation of the structure-function mechanism of ApoE. The ε4-allele variant of apolipoprotein E (ApoE4) is the strongest genetic risk factor for Alzheimer’s disease, although it only differs from its neutral counterpart ApoE3 by a single amino acid substitution. While ApoE4 influences the formation of plaques and neurofibrillary tangles, the structural determinants of pathogenicity remain undetermined due to limited structural information. Previous studies have led to conflicting models of the C-terminal region positioning with respect to the N-terminal domain across isoforms largely because the data are potentially confounded by the presence of heterogeneous oligomers. Here, we apply a combination of single-molecule spectroscopy and molecular dynamics simulations to construct an atomically detailed model of monomeric ApoE4 and probe the effect of lipid association. Importantly, our approach overcomes previous limitations by allowing us to work at picomolar concentrations where only the monomer is present. Our data reveal that ApoE4 is far more disordered and extended than previously thought and retains significant conformational heterogeneity after binding lipids. Comparing the proximity of the N- and C-terminal domains across the three major isoforms (ApoE4, ApoE3, and ApoE2) suggests that all maintain heterogeneous conformations in their monomeric form, with ApoE2 adopting a slightly more compact ensemble. Overall, these data provide a foundation for understanding how ApoE4 differs from nonpathogenic and protective variants of the protein.
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DOI：
10.1016/j.bbapap.2020.140535
发表时间：
2020-12-01
影响因子：
3.2
作者：
Dolai, Subhrajyoti;Cherakara, Sreelakshmi;Garai, Kanchan
通讯作者：
Garai, Kanchan
影响因子：
4.6
作者：
Dashti, Monireh;Kulik, Willem;Hoek, Frans;Veerman, Enno C.;Peppelenbosch, Maikel P.;Rezaee, Farhad
通讯作者：
Rezaee, Farhad
影响因子：
2.9
作者：
Garai, Kanchan;Baban, Berevan;Frieden, Carl
通讯作者：
Frieden, Carl
影响因子：
11.4
作者：
Gallop, Jennifer L.;Jao, Christine C.;T McMahon, Harvey
通讯作者：
T McMahon, Harvey
影响因子：
11.8
作者：
Miller, Sharon E.;Mathiasen, Signe;Bright, Nicholas A.;Pierre, Fabienne;Kelly, Bernard T.;Kladt, Nikolay;Schauss, Astrid;Merrifield, Christien J.;Stamou, Dimitrios;Hoening, Stefan;Owen, David J.
通讯作者：
Owen, David J.