使用非变性聚丙烯酰胺凝胶电泳人的MxA多亚基蛋白复合物的表征
Summary
This article describes a simple and rapid protocol to evaluate the oligomeric state of the dynamin-like GTPase MxA protein from lysates of human cells using a combination of non-denaturing PAGE with western blot analysis.
Abstract
The formation of oligomeric complexes is a crucial prerequisite for the proper structure and function of many proteins. The interferon-induced antiviral effector protein MxA exerts a broad antiviral activity against many viruses. MxA is a dynamin-like GTPase and has the capacity to form oligomeric structures of higher order. However, whether oligomerization of MxA is required for its antiviral activity is an issue of debate. We describe here a simple protocol to assess the oligomeric state of endogenously or ectopically expressed MxA in the cytoplasmic fraction of human cell lines by non-denaturing polyacrylamide gel electrophoresis (PAGE) in combination with Western blot analysis. A critical step of the protocol is the choice of detergents to prevent aggregation and/or precipitation of proteins particularly associated with cellular membranes such as MxA, without interfering with its enzymatic activity. Another crucial aspect of the protocol is the irreversible protection of the free thiol groups of cysteine residues by iodoacetamide to prevent artificial interactions of the protein. This protocol is suitable for a simple assessment of the oligomeric state of MxA and furthermore allows a direct correlation of the antiviral activity of MxA interface mutants with their respective oligomeric states.
Introduction
蛋白质的四级结构起着许多细胞过程至关重要的作用。信号通路，基因表达，和酶的激活/停用所有依赖蛋白复合物1-4的正确组装。这个过程也被称为均聚物或杂低聚是由于不可逆的共价的或可逆的静电和疏水蛋白 – 蛋白相互作用。低聚不仅多样化的不同的细胞过程，而不增加基因组的大小，而且还提供了策略蛋白质来构建稳定的复合物是对变性和降解5更耐。在低聚缺陷对蛋白质的功能产生影响，并可能导致疾病的发展。例如，酶苯丙氨酸羟化酶形成四聚体复合物。蛋白质复合物内的一些突变可以削弱四聚体的形成，并导致该疾病苯丙酮尿症6。
<p class ="“jove_content”">人MxA蛋白是干扰素（IFN）诱导的抗病毒效应蛋白施加对抗各种RNA的一个广泛的抗病毒活性以及DNA病毒7。它属于dynamin上样大GTP酶超家族，并具有在体外形成8个大寡聚结构的能力。齐聚已建议，以保护从MxA蛋白快速降解9,10。尽管许多研究小组加紧努力，作用的分子机制在很大程度上仍然难以捉摸和的MxA为它的抗病毒功能齐聚国家的作用正在辩论9,11,12。在这方面，高和同事提出，其中的MxA通过在大环状寡聚结构11的形式的病毒核蛋白相互作用而发挥其抗病毒活性的模型。然而，最近，我们证明了MxA蛋白二聚体具有抗病毒活性，流感病毒12的核蛋白进行交互。乙ASED上的MxA的晶体结构，高和同事鉴定在这对于其在体外低聚和其抗病毒功能11,13临界界面区域几个氨基酸残基。因此，为了阐明它的MxA的寡聚状态发挥抗病毒活性，我们试图建立一个简单的协议，以快速地确定在人类细胞中表达以及内源的MxAIFNα刺激之后表达的MxA界面突变体的oligmeric状态。虽然有通常用于研究蛋白质之间的相互作用，如分割绿色荧光蛋白的许多技术（分割-GFP）互补实验14，表面等离子体共振15和荧光共振能量转移（FRET）16，它们不提供寡聚蛋白复合物的精确化学计量的信息。此特定方面的调查，技术如多角度光散射（MALS）17和分析超速离心18是非常有用的。通常，使用这些方法分析的蛋白质是纯化的蛋白质。低聚方法还可能依赖于其他细胞因子。如果这些因素都是未知的，所述分析是比较困难的。此外，一些蛋白质难以在大肠杆菌表达大肠杆菌和净化。因此，这些方法都没有来分析在蜂窝环境蛋白低聚的最佳选择。此外，这些技术需要昂贵的仪器这是不容易获得的。
非变性聚丙烯酰胺凝胶电泳（PAGE），大小排阻层析或化学交联，随后通过常规的十二烷基硫酸钠（SDS）-PAGE是用于从细胞裂解物2,19,20形成低聚物的特征的有用工具。这些方法不需要专门的设备，并且可以是容易的performed在标准实验室。我们最初评价为不变地导致非特异性聚集和MxA蛋白的沉淀的各种化学交联的协议。因此，我们接下来要测试的非变性PAGE协议。非变性PAGE中排除使用SDS，和蛋白质的迁移取决于其天然电荷。蓝变性PAGE使用考马斯亮蓝G250加载蛋白质具有整体负电荷，类似于SDS，但不使蛋白质变性21。不幸的是，考马斯在高盐和通常包括在裂解缓冲液的二价阳离子（ 如 Mg 2+离子 ）的存在下艳蓝沉淀。根据所使用的缓冲液中，可能难以分析未经可能对所述寡聚蛋白复合物的作用的步骤进一步优化的样本。
在这里，我们提出了基于以前出版的方法22来确定齐聚一个简单的协议使用非变性PAGE蜂窝裂解物衍生的人MxA蛋白。
Protocol
Representative Results
Discussion
在这里，我们描述一个简单的方法，它允许通过非变性PAGE，随后通过Western印迹分析在哺乳动物细胞中表达的蛋白质的寡聚状态的快速测定。这种方法的主要优点是，一个给定的蛋白的寡聚状态可以从没有事先的蛋白质纯化全细胞裂解物来确定。这可能是对于低聚或发挥它们的相关联功能的辅助因子蛋白重要。此外，该蛋白仍然在其天然状态，如果进一步从凝胶中提取，酶活性或其它蛋白质的功?…
Divulgations
The authors have nothing to disclose.
Acknowledgements
This work was funded by a Grant from the Swiss National Science foundation (Grant nr. 31003A_143834) to JP.
Materials
| Slide-A-Lyzer MINI Dialysis Units, 10K MWCO, 0.5 mL | Thermo Fisher Scientific | 69570 | Pre-equilibrate in dialysis buffer ( if Glycerol removal is desired) Can be self-made according to Fiala et al. 2011 |
| 4–15% Mini-PROTEAN TGX Precast Protein Gels, 10-well, | Bio-Rad | 456-1083 | Pre-run in running buffer to adjust buffer system |
| cOmplete, Mini, EDTA-free | Roche | 11836170001 | use 1 tablet per 50 ml |
| PBS, pH 7.4 bottle a 500ml Gibco | Thermo Fisher Scientific | 14190-094 | |
| Ponceau S solution | Sigma-Aldrich | P7170 | toxic! wear gloves and protect eyes! |
| NativeMark Unstained Protein Standard 50ul | Invitrogen | P/N 57030 | load 5 ul/well |
| A549 cells | ATCC | ATCC CCL185 | Grow in growth medium (see Table 1) |
| Vero cells | ATCC | ATCC CCL81 | Grow in growth medium (see Table 1) |
| anti-Mx1 antibody | Novus Biologicals | H00004599_D01P | Use at a 1:1000 dilution |
| ECL Anti-rabbit IgG, Horseradish Peroxidase linked whole antibody (from donkey) | GE-Healthcare | NA934V | Use at a 1:10000 dilution |
| 0.5% Trypsin-EDTA (1x) Life Technologies | Thermo Fisher | 15400-054 | |
| Iodoacetamide 5g | Sigma-Aldrich | I-6125 | stock 100mM |
| Bromphenolblue | Sigma-Aldrich | B0126-25G | |
| DMEM +4.5g/l Gluc,+L-Glut,+Pyruvate life technologies | Thermo Fisher Scientific | 41966-029 | |
| Pen Strep 100 x 100ml life technologies | Thermo Fisher Scientific | 15140 – 130 | |
| Glutamax 100xStock, 100ml life technologies | Thermo Fisher Scientific | 350500-038 | |
| Fetal Bovine Serum, Dialyzed , US Origin 500ml Gibco Lot:42G9552K | Thermo Fisher Scientific | 10270-106 | |
| Cellulose filter paper | Bio-Rad | 1703965 | |
| PVDV blotting membrane | GE-Healthcare | 10600022 | |
| Tris(hydroxymethyl)aminomethane | Biosolve | 0020092391BS | |
| sodium fluoride (NaF) | Sigma Aldrich | S-7920 | |
| NP-40 | Calbiochem | 492015 | |
| cOmplete, Mini, EDTA-free | Roche | 11836170001 | |
| Tween 20 | Calbiochem | 6555204 | |
| CHAPS 10% solution | Amresco | N907 | |
| DL-Dithiothreitol (DTT) | Sigma Aldrich | 43819 | |
| Glycine | Biosolve | 0007132391BS | |
| sodium orthovanadate (Na3VO4) | Sigma Aldrich | 450243 | |
| Glycerol | Sigma Aldrich | G7757 | |
| b-Glycerophospate | Sigma Aldrich | G9422 | |
| Milk powder | Migros/Switzerland | ||
| Methanol | Millipore | 1.06009 | |
| sodium cloride (NaCl) | Sigma Aldrich | 71380 | |
| magnesium chloride (MgCl2) | Amresco | 288 | |
| Sodium dodecyl sulphate (SDS) | Sigma Aldrich | L4509 | |
| sodium hydroxide (NaOH) | Sigma Aldrich | S-8045 |
References
- Baisamy, L., Jurisch, N., Diviani, D. Leucine zipper-mediated homo-oligomerization regulates the Rho-GEF activity of AKAP-Lbc. J Biol Chem. 280, 15405-15412 (2005).
- Chen, C. P., Posy, S., Ben-Shaul, A., Shapiro, L., Honig, B. H. Specificity of cell-cell adhesion by classical cadherins: Critical role for low-affinity dimerization through beta-strand swapping. Proc Natl Acad Sci U S A. 102, 8531-8536 (2005).
- Jackson-Fisher, A. J., Chitikila, C., Mitra, M., Pugh, B. F. A role for TBP dimerization in preventing unregulated gene expression. Mol Cell. 3, 717-727 (1999).
- Torshin, I. Activating oligomerization as intermediate level of signal transduction: analysis of protein-protein contacts and active sites in several glycolytic enzymes. Front Biosci. 4, 557-570 (1999).
- Goodsell, D. S., Olson, A. J. Structural symmetry and protein function. Annu Rev Biophys Biomol Struct. 29, 105-153 (2000).
- Flydal, M. I., Martinez, A. Phenylalanine hydroxylase: function, structure, and regulation. IUBMB Life. 65, 341-349 (2013).
- Haller, O., Kochs, G. Human MxA protein: an interferon-induced dynamin-like GTPase with broad antiviral activity. J Interferon Cytokine Res. 31, 79-87 (2011).
- Haller, O., Staeheli, P., Schwemmle, M., Kochs, G. Mx GTPases: dynamin-like antiviral machines of innate immunity. Trends Microbiol. 23, 154-163 (2015).
- Di Paolo, C., Hefti, H. P., Meli, M., Landis, H., Pavlovic, J. Intramolecular backfolding of the carboxyl-terminal end of MxA protein is a prerequisite for its oligomerization. J Biol Chem. 274, 32071-32078 (1999).
- Janzen, C., Kochs, G., Haller, O. A monomeric GTPase-negative MxA mutant with antiviral activity. J Virol. 74, 8202-8206 (2000).
- Gao, S., et al. Structure of myxovirus resistance protein a reveals intra- and intermolecular domain interactions required for the antiviral function. Immunity. 35, 514-525 (2011).
- Nigg, P. E., Pavlovic, J. Oligomerization and GTP-binding Requirements of MxA for Viral Target Recognition and Antiviral Activity against Influenza A Virus. J Biol Chem. 290, 29893-29906 (2015).
- Gao, S., et al. Structural basis of oligomerization in the stalk region of dynamin-like MxA. Nature. 465, 502-506 (2010).
- Ghosh, I., Hamilton, A. D., Regan, L. Antiparallel leucine zipper-directed protein reassembly: Application to the green fluorescent protein. J Am Chem Soc. 122, 5658-5659 (2000).
- Patching, S. G. Surface plasmon resonance spectroscopy for characterisation of membrane protein-ligand interactions and its potential for drug discovery. Biochim Biophys Acta. 1838, 43-55 (2014).
- Kenworthy, A. K. Imaging protein-protein interactions using fluorescence resonance energy transfer microscopy. Methods. 24, 289-296 (2001).
- Wyatt, P. J. Light-Scattering and the Absolute Characterization of Macromolecules. Analytica Chimica Acta. 272 (93), 1-40 (1993).
- Howlett, G. J., Minton, A. P., Rivas, G. Analytical ultracentrifugation for the study of protein association and assembly. Curr Opin Chem Biol. 10, 430-436 (2006).
- Fiala, G. J., Schamel, W. W., Blumenthal, B. Blue native polyacrylamide gel electrophoresis (BN-PAGE) for analysis of multiprotein complexes from cellular lysates. J Vis Exp. , (2011).
- Zou, H., Li, Y., Liu, X., Wang, X. An APAF-1.cytochrome c multimeric complex is a functional apoptosome that activates procaspase-9. J Biol Chem. 274, 11549-11556 (1999).
- Schagger, H., Cramer, W. A., von Jagow, G. Analysis of molecular masses and oligomeric states of protein complexes by blue native electrophoresis and isolation of membrane protein complexes by two-dimensional native electrophoresis. Anal Biochem. 217, 220-230 (1994).
- Walker, J. M. Nondenaturing polyacrylamide gel electrophoresis of proteins. Methods Mol Biol. 32, 17-22 (1994).
- Stoscheck, C. M. Quantitation of protein. Methods Enzymol. 182, 50-68 (1990).
- Wisskirchen, C., Ludersdorfer, T. H., Muller, D. A., Moritz, E., Pavlovic, J. Interferon-induced antiviral protein MxA interacts with the cellular RNA helicases UAP56 and URH49. J Biol Chem. 286, 34743-34751 (2011).
- Stertz, S., et al. Interferon-induced, antiviral human MxA protein localizes to a distinct subcompartment of the smooth endoplasmic reticulum. J Interferon Cytokine Res. 26, 650-660 (2006).
- Seddon, A. M., Curnow, P., Booth, P. J. Membrane proteins, lipids and detergents: not just a soap opera. Biochim Biophys Acta. 1666, 105-117 (2004).
- Kochs, G., Haener, M., Aebi, U., Haller, O. Self-assembly of human MxA GTPase into highly ordered dynamin-like oligomers. J Biol Chem. 277, 14172-14176 (2002).
- Kochs, G., Haller, O. GTP-bound human MxA protein interacts with the nucleocapsids of Thogoto virus (Orthomyxoviridae). J Biol Chem. 274, 4370-4376 (1999).
- Reichelt, M., Stertz, S., Krijnse-Locker, J., Haller, O., Kochs, G. Missorting of LaCrosse virus nucleocapsid protein by the interferon-induced MxA GTPase involves smooth ER membranes. Traffic. 5, 772-784 (2004).
- Wisskirchen, C., Ludersdorfer, T. H., Muller, D. A., Moritz, E., Pavlovic, J. The cellular RNA helicase UAP56 is required for prevention of double-stranded RNA formation during influenza A virus infection. J Virol. 85, 8646-8655 (2011).
