RNA催化剂作为记者为筛选药物对RNA编辑在锥虫
Summary
A highly sensitive ribozyme-based assay, applicable to high-throughput screening of chemicals targeting the unique process of RNA editing in trypanosomatid pathogens, is described in this paper. Inhibitors can be used as tools for hypothesis-driven analysis of the RNA editing process and ultimately as therapeutics.
Abstract
实质性的进展已经取得了确定的线粒体RNA编辑在锥虫的机制。同样，相当大的进展已经取得了识别editosome络合物的催化RNA编辑的组件。但是，目前还不清楚这些蛋白质是如何协同工作。从对editosome高通量筛选获得的化学化合物可以阻止或影响在编辑周期的一个或多个步骤。因此，新化合物的鉴定将产生有价值的分子探针解剖editosome功能和组装。在以前的研究中， 在体外测定法的编辑进行了使用放射性标记的RNA。这些测定法是耗时，低效和不适合于高通量的目的。在这里，均匀的荧光为基础的“混合和计量”锤头状核酶体外记者分析监测RNA编辑，呈现。仅作为RNA编辑的结果锤头状核酶荧光共振能量转移（FRET）寡基板发生裂解。这反过来导致荧光团与猝灭剂，从而产生一个信号分离。与此相反，当editosome功能受到抑制，荧光信号会被淬灭。这是一个高度敏感和简单的分析，应该是普遍适用于体外 RNA编辑或化学物质，可以抑制editosome功能的高通量筛选监控。
Introduction
RNA编辑，转录后修饰的mRNA的过程中，首先被锥虫1发现。从那时起，大量的工作已经在后面学习中的RNA编辑布氏锥虫 2,3机制进行的。在一系列的酶反应中，editosome，约20蛋白核心复合物，产生成熟的mRNA线粒体的能量产生的氧化磷酸化系统的多个组件。催化事件的顺序是信使核糖核酸，尿苷酸（U）增加或删除，并结扎，所决定的指导的RNA（gRNAs）4。
除了 核心editosome复杂的蛋白质，一些辅助因子也已确定5-7。这些蛋白质大多见于分组独立的复合物。然而，蛋白质装配在芯editosome复杂的顺序和核心复合物与该配件的交互模式配合物尚未确定。针对RNA编辑的过程中锥虫可提供化学解剖，援助在研究editosome复杂的装配和功能。此外，在几个editosome蛋白质功能的研究表明在不同人生阶段的必要性，指出其潜在的药物靶点8-12。因此，editosome的发现抑制剂也可作为对锥虫的先导化合物。这是及时的，因为目前市面上所引致的锥虫病的药物是有毒的，低效和昂贵13,14。
一个高效，便捷的体外试验要探索的化学宇宙，阻止RNA编辑特异性抑制剂。三个实验已经开发并用于监视editosome活动：（a）全轮体外 RNA编辑分析15（二）预切割体外 RNA编辑实验16,17，一ND（三）锤头状核酶（HHR）为基础的检测18。前两个实验依靠编辑的产品（ATP酶6基因）与放射性的帮助下直接观察。该HHR基测定法使用了被建模的行为作为经编辑的核酶的ATP酶6 mRNA的修改版本。功能核酶则特异性切割放射性标记的RNA底物，作为一名记者。最近，MOSHIRI 等人开发了一种“混合，并测量”HHR-基于体外报告基因分析来监测RNA编辑其中的放射性标记的RNA底物被替换为荧光共振能量转移（FRET）底物19。该测定法的原理的优点是：（a）它是一种快速和方便的混合和测定法的测量类型，为生产活性核酶和底物裂解的同时出现在同一试管中低体积（ 即 20微升），（二）它避免了使用放射性标记的物质，（C）的灵敏度是一个通过荧光仪在微滴定板格式，以及（d）一个高信噪比fforded。使用这种测定法，对纯化的editosome已知的RNA编辑连接酶抑制剂的作用被证实19。这个实验验证了分析的快速鉴定RNA编辑酶抑制剂，主要针对来自T.整个editosomes 布氏 。
图1是一个详细的一步一步的示意性的基于荧光的体外 RNA编辑测定。这个协议可以被用于监测在体外 RNA编辑或很容易地适应用于筛选各种比例的化合物库。
Protocol
Representative Results
Discussion
一种新型的高通量筛选方法来确定对锥虫的RNA编辑复杂的抑制剂已提交，为药物发现的新工具来对抗引起的锥虫病。基于FRET的核酶法已被广泛地用于不同的用途20-22;然而，我们动用的体外监测RNA编辑活动19 FRET为基础的核酶分析的能力。该测定可能适用于其他类型的RNA编辑在真核生物，如哺乳动物23的核编码的RNA的核苷酸替换编辑。
该测定中的?…
Declarações
The authors have nothing to disclose.
Acknowledgements
Najmeh Nikpour and Fiona Alum provided suggestions and edited this manuscript. Department of Biochemistry at McGill University supported HM and VM with the CIHR Training Initiative in Chemical Biology. This work was supported by Canadian Institute of Health Research (CIHR) grant 119464 (to R. S.).
Materials
| Name of Material/ Equipment | Company | Catalog Number | Comments/Description |
| SDM-79 Medium | Gibco by life technologies | ||
| Fetal Bovine Serum | life technologies | 12483-020 | heat inactivation at 550C for 1 h |
| Hemin, minimum 80% | Sigma | H5533-10G | |
| Penicillin-Streptomycin Sollution | Fisher Scientific | MT-30-002-CI | |
| Dnase 1 recombinant, Rnase Free | Roche | 4716728001 | |
| T7 RiboMax Express Large scale RNA production system | Promega | P1320 | |
| Kimble Kontes Dounce Tissue Grinders | Fisher Scientific | K885300-0040 | |
| Gradient Master, ver 5.25 | Biocomp | 107-201M | |
| Ultra Clear Tube, 13.2ML | Beckman Coulter | 344059 | |
| Optima L-100XP Ultracentrifuge | Beckman Coulter | 392052 | |
| SW 41 Ti ROTOR | Beckman Coulter | 331336 | |
| MicroSeal 'B' Seal, Seals | Biorad | MSB1001 | |
| CFX 384 Touch Real-Time PCR Detection System | Biorad | 185-5484 | |
| Acryl/Bis solution (19: 1), 40% (w/v) | Bio Basic | A0006-500ML | |
| Urea, Molecular biology grade, 1Kg | life technologies | AM9902 |
Referências
- Benne, R., et al. transcript of the frameshifted coxII gene from trypanosome mitochondria contains four nucleotides that are not encoded in the DNA. Cell. 46, 819-826 (1986).
- Hajduk, S., Ochsenreiter, T. RNA editing in kinetoplastids. RNA biology. 7, 229-236 (2010).
- Aphasizhev, R., Aphasizheva, I. Uridine insertion/deletion editing in trypanosomes: a playground for RNA-guided information transfer. Wiley interdisciplinary reviews RNA. 2, 669-685 (2011).
- Seiwert, S. D., Stuart, K. RNA editing: transfer of genetic information from gRNA to precursor mRNA in vitro. Science. 266, 114-117 (1994).
- Weng, J., et al. Guide RNA-binding complex from mitochondria of trypanosomatids. Molecular. 32, 198-209 (2008).
- Hashimi, H., Zikova, A., Panigrahi, A. K., Stuart, K. D., Lukes, J. TbRGG1, an essential protein involved in kinetoplastid RNA metabolism that is associated with a novel multiprotein complex. RNA. 14, 970-980 (2008).
- Ammerman, M. L., et al. Architecture of the trypanosome RNA editing accessory complex, MRB1. Nucleic Acids Res. 40, 5637-5650 (2012).
- Huang, C. E., O’Hearn, S. F., Sollner-Webb, B. Assembly and function of the RNA editing complex in Trypanosoma brucei requires band III protein. Molecular and cellular biology. 22, 3194-3203 (2002).
- Carnes, J., Trotter, J. R., Peltan, A., Fleck, M., Stuart, K. RNA editing in Trypanosoma brucei requires three different editosomes. Molecular and cellular biology. 28, 122-130 (2008).
- Hearn, S. F., Huang, C. E., Hemann, M., Zhelonkina, A., Sollner-Webb, B. Trypanosoma brucei RNA editing complex: band II is structurally critical and maintains band V ligase, which is nonessential. Molecular and cellular biology. 23, 7909-7919 (2003).
- Schnaufer, A., et al. An RNA ligase essential for RNA editing and survival of the bloodstream form of Trypanosoma brucei. Science. 291, 2159-2162 (2001).
- Tarun, S. Z., et al. KREPA6 is an RNA-binding protein essential for editosome integrity and survival of Trypanosoma brucei. RNA. 14, 347-358 (2008).
- Croft, S. L., Barrett, M. P., Urbina, J. A. Chemotherapy of trypanosomiases and leishmaniasis. Trends in parasitology. 21, 508-512 (2005).
- Denise, H., Barrett, M. P. Uptake and mode of action of drugs used against sleeping sickness. Biochemical pharmacology. 61, 1-5 (2001).
- Seiwert, S. D., Heidmann, S., Stuart, K. Direct visualization of uridylate deletion in vitro suggests a mechanism for kinetoplastid RNA editing. Cell. 84, 831-841 (1996).
- Igo, R. P., Palazzo, S. S., Burgess, M. L., Panigrahi, A. K., Stuart, K. Uridylate addition and RNA ligation contribute to the specificity of kinetoplastid insertion RNA editing. Molecular and cellular biology. 20, 8447-8457 (2000).
- Igo, R. P., et al. Role of uridylate-specific exoribonuclease activity in Trypanosoma brucei RNA editing. Eukaryotic cell. 1, 112-118 (2002).
- Wang, B., Salavati, R., Heidmann, S., Stuart, K. A hammerhead ribozyme substrate and reporter for in vitro kinetoplastid RNA editing. RNA. 8, 548-554 (2002).
- Moshiri, H., Salavati, R. A fluorescence-based reporter substrate for monitoring RNA editing in trypanosomatid pathogens. Nucleic Acids Res. 38, e138 (2010).
- Jenne, A., et al. Rapid identification and characterization of hammerhead-ribozyme inhibitors using fluorescence-based technology. Nature. 19, 56-61 (2001).
- Hartig, J. S., et al. Protein-dependent ribozymes report molecular interactions in real time. Nature. 20, 717-722 (2002).
- Famulok, M. Allosteric aptamers and aptazymes as probes for screening approaches. Current opinion in molecular therapeutics. 7, 137-143 (2005).
- Teng, B., Burant, C. F., Davidson, N. O. Molecular cloning of an apolipoprotein B messenger RNA editing protein. Science. 260, 1816-1819 (1993).
- Jurica, M. S. Searching for a wrench to throw into the splicing machine. Nature chemical biology. 4, 3-6 (2008).
- Spahn, C., Prescott, C. Throwing a spanner in the works: antibiotics and the translation apparatus. Journal of molecular medicine. 74, 423-439 (1996).
