1
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Yıldırım Akdeniz G, Timuçin AC. Structure based computational RNA design towards MafA transcriptional repressor implicated in multiple myeloma. J Mol Graph Model 2024; 132:108839. [PMID: 39096645 DOI: 10.1016/j.jmgm.2024.108839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 07/24/2024] [Accepted: 07/29/2024] [Indexed: 08/05/2024]
Abstract
Multiple myeloma is recognized as the second most common hematological cancer. MafA transcriptional repressor is an established mediator of myelomagenesis. While there are multitude of drugs available for targeting various effectors in multiple myeloma, current literature lacks a candidate RNA based MafA modulator. Thus, using the structure of MafA homodimer-consensus target DNA, a computational effort was implemented to design a novel RNA based chemical modulator against MafA. First, available MafA-consensus DNA structure was employed to generate an RNA library. This library was further subjected to global docking to select the most plausible RNA candidates, preferring to bind DNA binding region of MafA. Following global docking, MD-ready complexes that were prepared via local docking program, were subjected to 500 ns of MD simulations. First, each of these MD simulations were analyzed for relative binding free energy through MM-PBSA method, which pointed towards a strong RNA based MafA binder, RNA1. Second, through a detailed MD analysis, RNA1 was shown to prefer binding to a single monomer of the dimeric DNA binding domain of MafA using higher number of hydrophobic interactions compared with positive control MafA-DNA complex. At the final phase, a principal component analyses was conducted, which led us to identify the actual interaction region of RNA1 and MafA monomer. Overall, to our knowledge, this is the first computational study that presents an RNA molecule capable of potentially targeting MafA protein. Furthermore, limitations of our study together with possible future implications of RNA1 in multiple myeloma were also discussed.
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Affiliation(s)
- Güneş Yıldırım Akdeniz
- Department of Molecular Biology, Genetics and Bioengineering, Faculty of Engineering and Natural Sciences, Sabancı University, 34956, Tuzla, İstanbul, Turkey.
| | - Ahmet Can Timuçin
- Department of Molecular Biology and Genetics, Faculty of Engineering and Natural Sciences, Acıbadem Mehmet Ali Aydınlar University, 34752, Ataşehir, İstanbul, Turkey.
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2
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Huang YJ, Chen JY, Yan M, Davis AG, Miyauchi S, Chen L, Hao Y, Katz S, Bejar R, Abdel-Wahab O, Fu XD, Zhang DE. RUNX1 deficiency cooperates with SRSF2 mutation to induce multilineage hematopoietic defects characteristic of MDS. Blood Adv 2022; 6:6078-6092. [PMID: 36206200 PMCID: PMC9772487 DOI: 10.1182/bloodadvances.2022007804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 08/15/2022] [Accepted: 09/13/2022] [Indexed: 12/15/2022] Open
Abstract
Myelodysplastic syndromes (MDSs) are a heterogeneous group of hematologic malignancies with a propensity to progress to acute myeloid leukemia. Causal mutations in multiple classes of genes have been identified in patients with MDS with some patients harboring more than 1 mutation. Interestingly, double mutations tend to occur in different classes rather than the same class of genes, as exemplified by frequent cooccurring mutations in the transcription factor RUNX1 and the splicing factor SRSF2. This prototypic double mutant provides an opportunity to understand how their divergent functions in transcription and posttranscriptional regulation may be altered to jointly promote MDS. Here, we report a mouse model in which Runx1 knockout was combined with the Srsf2 P95H mutation to cause multilineage hematopoietic defects. Besides their additive and synergistic effects, we also unexpectedly noted a degree of antagonizing activity of single mutations in specific hematopoietic progenitors. To uncover the mechanism, we further developed a cellular model using human K562 cells and performed parallel gene expression and splicing analyses in both human and murine contexts. Strikingly, although RUNX1 deficiency was responsible for altered transcription in both single and double mutants, it also induced dramatic changes in global splicing, as seen with mutant SRSF2, and only their combination induced missplicing of genes selectively enriched in the DNA damage response and cell cycle checkpoint pathways. Collectively, these data reveal the convergent impact of a prototypic MDS-associated double mutant on RNA processing and suggest that aberrant DNA damage repair and cell cycle regulation critically contribute to MDS development.
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Affiliation(s)
- Yi-Jou Huang
- Moores Cancer Center, UC San Diego (UCSD), La Jolla, CA
- Department of Molecular Biology, UCSD, La Jolla, CA
| | - Jia-Yu Chen
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA
| | - Ming Yan
- Moores Cancer Center, UC San Diego (UCSD), La Jolla, CA
| | - Amanda G. Davis
- Moores Cancer Center, UC San Diego (UCSD), La Jolla, CA
- Department of Molecular Biology, UCSD, La Jolla, CA
| | | | - Liang Chen
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA
| | - Yajing Hao
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA
| | - Sigrid Katz
- Moores Cancer Center, UC San Diego (UCSD), La Jolla, CA
| | - Rafael Bejar
- Moores Cancer Center, UC San Diego (UCSD), La Jolla, CA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Xiang-Dong Fu
- Moores Cancer Center, UC San Diego (UCSD), La Jolla, CA
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA
| | - Dong-Er Zhang
- Moores Cancer Center, UC San Diego (UCSD), La Jolla, CA
- Department of Molecular Biology, UCSD, La Jolla, CA
- Department of Pathology, UC San Diego, La Jolla, CA
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3
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Amundarain A, Pastor F, Prósper F, Agirre X. Aptamers, a New Therapeutic Opportunity for the Treatment of Multiple Myeloma. Cancers (Basel) 2022; 14:5471. [PMID: 36358889 PMCID: PMC9657029 DOI: 10.3390/cancers14215471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 10/31/2022] [Accepted: 11/04/2022] [Indexed: 08/30/2023] Open
Abstract
Multiple Myeloma (MM) remains an incurable disease due to high relapse rates and fast development of drug resistances. The introduction of monoclonal antibodies (mAb) has caused a paradigm shift in MM treatment, paving the way for targeted approaches with increased efficacy and reduced toxicities. Nevertheless, antibody-based therapies face several difficulties such as high immunogenicity, high production costs and limited conjugation capacity, which we believe could be overcome by the introduction of nucleic acid aptamers. Similar to antibodies, aptamers can bind to their targets with great affinity and specificity. However, their chemical nature reduces their immunogenicity and production costs, while it enables their conjugation to a wide variety of cargoes for their use as delivery agents. In this review, we summarize several aptamers that have been tested against MM specific targets with promising results, establishing the rationale for the further development of aptamer-based strategies against MM. In this direction, we believe that the study of novel plasma cell surface markers, the development of intracellular aptamers and further research on aptamers as building blocks for complex nanomedicines will lead to the generation of next-generation targeted approaches that will undoubtedly contribute to improve the management and life quality of MM patients.
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Affiliation(s)
- Ane Amundarain
- Center for Applied Medical Research (CIMA), IDISNA, University of Navarra, 31008 Pamplona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), 31008 Pamplona, Spain
| | - Fernando Pastor
- Center for Applied Medical Research (CIMA), IDISNA, University of Navarra, 31008 Pamplona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), 31008 Pamplona, Spain
| | - Felipe Prósper
- Center for Applied Medical Research (CIMA), IDISNA, University of Navarra, 31008 Pamplona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), 31008 Pamplona, Spain
- Hematology Department, Clínica Universidad de Navarra, CCUN, University of Navarra, 31008 Pamplona, Spain
| | - Xabier Agirre
- Center for Applied Medical Research (CIMA), IDISNA, University of Navarra, 31008 Pamplona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), 31008 Pamplona, Spain
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4
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Yuhan J, Zhu L, Zhu L, Huang K, He X, Xu W. Cell-specific aptamers as potential drugs in therapeutic applications: A review of current progress. J Control Release 2022; 346:405-420. [PMID: 35489545 DOI: 10.1016/j.jconrel.2022.04.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/23/2022] [Accepted: 04/24/2022] [Indexed: 12/23/2022]
Abstract
Cell-specific aptamers are a promising emerging player in the field of disease therapy. This paper reviews the multidimensional research progress made in terms of their classification, modification, and application. Based on the target location of cell-specific aptamers, it is defined and classified cell-specific aptamers into three groups including aptamers for cell surface markers, aptamers for intracellular components, and aptamers for extracellular components. Moreover, the modification methods of aptamers to achieve improved stability and affinity are concluded. In addition, recent advances in the application of cell-specific aptamers are discussed, mainly focusing on the increasing research attraction of cell state improving helpers and cell recruitment mediators in the improvement of cellular microenvironments to achieve successful disease therapy. This review also highlights 11 types of clinical aptamer drugs. Finally, the challenges and future directions of potential clinical applications are presented. In summary, we believe that cell-specific aptamers are promising drugs in disease therapy.
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Affiliation(s)
- Jieyu Yuhan
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100083, China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Liye Zhu
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100083, China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Longjiao Zhu
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100083, China
| | - Kunlun Huang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Xiaoyun He
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Wentao Xu
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100083, China.
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5
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Fukunaga J, Nomura Y, Tanaka Y, Torigoe H, Nakamura Y, Sakamoto T, Kozu T. A G-quadruplex-forming RNA aptamer binds to the MTG8 TAFH domain and dissociates the leukemic AML1-MTG8 fusion protein from DNA. FEBS Lett 2020; 594:3477-3489. [PMID: 32870501 DOI: 10.1002/1873-3468.13914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/10/2020] [Accepted: 08/12/2020] [Indexed: 11/11/2022]
Abstract
MTG8 (RUNX1T1) is a fusion partner of AML1 (RUNX1) in the leukemic chromosome translocation t(8;21). The AML1-MTG8 fusion gene encodes a chimeric transcription factor. One of the highly conserved domains of MTG8 is TAFH which possesses homology with human TAF4 [TATA-box binding protein-associated factor]. To obtain specific inhibitors of the AML1-MTG8 fusion protein, we isolated RNA aptamers against the MTG8 TAFH domain using systematic evolution of ligands by exponential enrichment. All TAF aptamers contained guanine-rich sequences. Analyses of a TAF aptamer by NMR, CD, and mutagenesis revealed that it forms a parallel G-quadruplex structure in the presence of K+ . Furthermore, the aptamer could bind to the AML1-MTG8 fusion protein and dissociate the AML1-MTG8/DNA complex, suggesting that it can inhibit the dominant negative effects of AML1-MTG8 against normal AML1 function and serve as a potential therapeutic agent for leukemia.
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Affiliation(s)
- Junichi Fukunaga
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Japan
| | - Yusuke Nomura
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, Narashino, Japan.,Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Shinjuku-ku, Japan
| | - Yoichiro Tanaka
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Japan.,Facility for RI Research and Education, Instrumental Analysis Center, Research Initiatives and Promotion Organization, Yokohama National University, Hodogaya-ku, Japan
| | - Hidetaka Torigoe
- Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Shinjuku-ku, Japan
| | - Yoshikazu Nakamura
- Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo, Minato-ku, Japan.,Ribomic Inc., Minato-ku, Japan
| | - Taiichi Sakamoto
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, Narashino, Japan
| | - Tomoko Kozu
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Japan
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6
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Yoon S, Rossi JJ. Aptamers: Uptake mechanisms and intracellular applications. Adv Drug Deliv Rev 2018; 134:22-35. [PMID: 29981799 PMCID: PMC7126894 DOI: 10.1016/j.addr.2018.07.003] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 06/06/2018] [Accepted: 07/04/2018] [Indexed: 01/10/2023]
Abstract
The structural flexibility and small size of aptamers enable precise recognition of cellular elements for imaging and therapeutic applications. The process by which aptamers are taken into cells depends on their targets but is typically clathrin-mediated endocytosis or macropinocytosis. After internalization, most aptamers are transported to endosomes, lysosomes, endoplasmic reticulum, Golgi apparatus, and occasionally mitochondria and autophagosomes. Intracellular aptamers, or “intramers,” have versatile functions ranging from intracellular RNA imaging, gene regulation, and therapeutics to allosteric modulation, which we discuss in this review. Immune responses to therapeutic aptamers and the effects of G-quadruplex structure on aptamer function are also discussed.
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7
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Takada K, Amano R, Nomura Y, Tanaka Y, Sugiyama S, Nagata T, Katahira M, Nakamura Y, Kozu T, Sakamoto T. Characterisation of an aptamer against the Runt domain of AML1 (RUNX1) by NMR and mutational analyses. FEBS Open Bio 2018; 8:264-270. [PMID: 29435416 PMCID: PMC5794459 DOI: 10.1002/2211-5463.12368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/20/2017] [Accepted: 12/02/2017] [Indexed: 01/15/2023] Open
Abstract
Since the invention of systematic evolution of ligands by exponential enrichment, many short oligonucleotides (or aptamers) have been reported that can bind to a wide range of target molecules with high affinity and specificity. Previously, we reported an RNA aptamer that shows high affinity to the Runt domain (RD) of the AML1 protein, a transcription factor with roles in haematopoiesis and immune function. From kinetic and thermodynamic studies, it was suggested that the aptamer recognises a large surface area of the RD, using numerous weak interactions. In this study, we identified the secondary structure by nuclear magnetic resonance spectroscopy and performed a mutational study to reveal the residue critical for binding to the RD. It was suggested that the large contact area was formed by a DNA‐mimicking motif and a multibranched loop, which confers the high affinity and specificity of binding.
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Affiliation(s)
- Kenta Takada
- Department of Life and Environmental Sciences Faculty of Engineering Chiba Institute of Technology Narashino Japan
| | - Ryo Amano
- Department of Life and Environmental Sciences Faculty of Engineering Chiba Institute of Technology Narashino Japan
| | - Yusuke Nomura
- Division of Medical Devices National Institute of Health Sciences Tokyo Japan
| | - Yoichiro Tanaka
- Facility for RI Research and Education Instrumental Analysis Center Yokohama National University Japan
| | | | | | | | - Yoshikazu Nakamura
- RIBOMIC Inc.Tokyo Japan.,Department of Basic Medical Sciences Institute of Medical Science University of Tokyo Japan
| | - Tomoko Kozu
- Research Institute for Clinical Oncology Saitama Cancer CenterIna Japan
| | - Taiichi Sakamoto
- Department of Life and Environmental Sciences Faculty of Engineering Chiba Institute of Technology Narashino Japan
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8
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Dickey TH, Pyle AM. The SMAD3 transcription factor binds complex RNA structures with high affinity. Nucleic Acids Res 2017; 45:11980-11988. [PMID: 29036649 PMCID: PMC5714123 DOI: 10.1093/nar/gkx846] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 09/19/2017] [Indexed: 01/12/2023] Open
Abstract
Several members of the SMAD family of transcription factors have been reported to bind RNA in addition to their canonical double-stranded DNA (dsDNA) ligand. RNA binding by SMAD has the potential to affect numerous cellular functions that involve RNA. However, the affinity and specificity of this RNA binding activity has not been well characterized, which limits the ability to validate and extrapolate functional implications of this activity. Here we perform quantitative binding experiments in vitro to determine the ligand requirements for RNA binding by SMAD3. We find that SMAD3 binds poorly to single- and double-stranded RNA, regardless of sequence. However, SMAD3 binds RNA with large internal loops or bulges with high apparent affinity. This apparent affinity matches that for its canonical dsDNA ligand, suggesting a biological role for RNA binding by SMAD3.
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Affiliation(s)
- Thayne H Dickey
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Anna M Pyle
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA.,Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.,Department of Chemistry, Yale University, New Haven, CT 06511, USA
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9
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Amano R, Takada K, Tanaka Y, Nakamura Y, Kawai G, Kozu T, Sakamoto T. Kinetic and Thermodynamic Analyses of Interaction between a High-Affinity RNA Aptamer and Its Target Protein. Biochemistry 2016; 55:6221-6229. [PMID: 27766833 DOI: 10.1021/acs.biochem.6b00748] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AML1 (RUNX1) protein is an essential transcription factor involved in the development of hematopoietic cells. Several genetic aberrations that disrupt the function of AML1 have been frequently observed in human leukemia. AML1 contains a DNA-binding domain known as the Runt domain (RD), which recognizes the RD-binding double-stranded DNA element of target genes. In this study, we identified high-affinity RNA aptamers that bind to RD by systematic evolution of ligands by exponential enrichment. The binding assay using surface plasmon resonance indicated that a shortened aptamer retained the ability to bind to RD when 1 M potassium acetate was used. A thermodynamic study using isothermal titration calorimetry (ITC) showed that the aptamer-RD interaction is driven by a large enthalpy change, and its unfavorable entropy change is compensated by a favorable enthalpy change. Furthermore, the binding heat capacity change was identified from the ITC data at various temperatures. The aptamer binding showed a large negative heat capacity change, which suggests that a large apolar surface is buried upon such binding. Thus, we proposed that the aptamer binds to RD with long-range electrostatic force in the early stage of the association and then changes its conformation and recognizes a large surface area of RD. These findings about the biophysics of aptamer binding should be useful for understanding the mechanism of RNA-protein interaction and optimizing and modifying RNA aptamers.
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Affiliation(s)
- Ryo Amano
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology , 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Kenta Takada
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology , 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Yoichiro Tanaka
- Facility for RI Research and Education, Instrumental Analysis Center, Yokohama National University , 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Yoshikazu Nakamura
- Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo , Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.,Ribomic Inc. , 3-16-13 Shirokanedai, Minato-ku, Tokyo 108-0071, Japan
| | - Gota Kawai
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology , 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Tomoko Kozu
- Research Institute for Clinical Oncology , Saitama Cancer Center, Ina, Saitama 362-0806, Japan
| | - Taiichi Sakamoto
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology , 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
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10
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Espah Borujeni A, Mishler DM, Wang J, Huso W, Salis HM. Automated physics-based design of synthetic riboswitches from diverse RNA aptamers. Nucleic Acids Res 2016; 44:1-13. [PMID: 26621913 PMCID: PMC4705656 DOI: 10.1093/nar/gkv1289] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/30/2015] [Accepted: 11/05/2015] [Indexed: 01/31/2023] Open
Abstract
Riboswitches are shape-changing regulatory RNAs that bind chemicals and regulate gene expression, directly coupling sensing to cellular actuation. However, it remains unclear how their sequence controls the physics of riboswitch switching and activation, particularly when changing the ligand-binding aptamer domain. We report the development of a statistical thermodynamic model that predicts the sequence-structure-function relationship for translation-regulating riboswitches that activate gene expression, characterized inside cells and within cell-free transcription-translation assays. Using the model, we carried out automated computational design of 62 synthetic riboswitches that used six different RNA aptamers to sense diverse chemicals (theophylline, tetramethylrosamine, fluoride, dopamine, thyroxine, 2,4-dinitrotoluene) and activated gene expression by up to 383-fold. The model explains how aptamer structure, ligand affinity, switching free energy and macromolecular crowding collectively control riboswitch activation. Our model-based approach for engineering riboswitches quantitatively confirms several physical mechanisms governing ligand-induced RNA shape-change and enables the development of cell-free and bacterial sensors for diverse applications.
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Affiliation(s)
- Amin Espah Borujeni
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Dennis M Mishler
- Department of Biological Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Jingzhi Wang
- Department of Biological Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Walker Huso
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Howard M Salis
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA Department of Chemistry, Emory University, Atlanta, GA 30322, USA
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11
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Mondragón E, Maher LJ. Anti-Transcription Factor RNA Aptamers as Potential Therapeutics. Nucleic Acid Ther 2015; 26:29-43. [PMID: 26509637 PMCID: PMC4753637 DOI: 10.1089/nat.2015.0566] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Transcription factors (TFs) are DNA-binding proteins that play critical roles in regulating gene expression. These proteins control all major cellular processes, including growth, development, and homeostasis. Because of their pivotal role, cells depend on proper TF function. It is, therefore, not surprising that TF deregulation is linked to disease. The therapeutic drug targeting of TFs has been proposed as a frontier in medicine. RNA aptamers make interesting candidates for TF modulation because of their unique characteristics. The products of in vitro selection, aptamers are short nucleic acids (DNA or RNA) that bind their targets with high affinity and specificity. Aptamers can be expressed on demand from transgenes and are intrinsically amenable to recognition by nucleic acid-binding proteins such as TFs. In this study, we review several natural prokaryotic and eukaryotic examples of RNAs that modulate the activity of TFs. These examples include 5S RNA, 6S RNA, 7SK, hepatitis delta virus-RNA (HDV-RNA), neuron restrictive silencer element (NRSE)-RNA, growth arrest-specific 5 (Gas5), steroid receptor RNA activator (SRA), trophoblast STAT utron (TSU), the 3' untranslated region of caudal mRNA, and heat shock RNA-1 (HSR1). We then review examples of unnatural RNA aptamers selected to inhibit TFs nuclear factor-kappaB (NF-κB), TATA-binding protein (TBP), heat shock factor 1 (HSF1), and runt-related transcription factor 1 (RUNX1). The field of RNA aptamers for DNA-binding proteins continues to show promise.
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Affiliation(s)
- Estefanía Mondragón
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - Louis James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine , Rochester, Minnesota
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12
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Cabezas-Wallscheid N, Eichwald V, de Graaf J, Löwer M, Lehr HA, Kreft A, Eshkind L, Hildebrandt A, Abassi Y, Heck R, Dehof AK, Ohngemach S, Sprengel R, Wörtge S, Schmitt S, Lotz J, Meyer C, Kindler T, Zhang DE, Kaina B, Castle JC, Trumpp A, Sahin U, Bockamp E. Instruction of haematopoietic lineage choices, evolution of transcriptional landscapes and cancer stem cell hierarchies derived from an AML1-ETO mouse model. EMBO Mol Med 2013; 5:1804-20. [PMID: 24124051 PMCID: PMC3914523 DOI: 10.1002/emmm.201302661] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 08/28/2013] [Accepted: 08/28/2013] [Indexed: 11/11/2022] Open
Abstract
The t(8;21) chromosomal translocation activates aberrant expression of the AML1-ETO (AE) fusion protein and is commonly associated with core binding factor acute myeloid leukaemia (CBF AML). Combining a conditional mouse model that closely resembles the slow evolution and the mosaic AE expression pattern of human t(8;21) CBF AML with global transcriptome sequencing, we find that disease progression was characterized by two principal pathogenic mechanisms. Initially, AE expression modified the lineage potential of haematopoietic stem cells (HSCs), resulting in the selective expansion of the myeloid compartment at the expense of normal erythro- and lymphopoiesis. This lineage skewing was followed by a second substantial rewiring of transcriptional networks occurring in the trajectory to manifest leukaemia. We also find that both HSC and lineage-restricted granulocyte macrophage progenitors (GMPs) acquired leukaemic stem cell (LSC) potential being capable of initiating and maintaining the disease. Finally, our data demonstrate that long-term expression of AE induces an indolent myeloproliferative disease (MPD)-like myeloid leukaemia phenotype with complete penetrance and that acute inactivation of AE function is a potential novel therapeutic option.
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Affiliation(s)
- Nina Cabezas-Wallscheid
- Medical Center of the Johannes Gutenberg-University Mainz, Department of Internal Medicine III, Division of Translational and Experimental Oncology, Mainz, Germany; German Cancer Research Center, Department of Stem Cells and Cancer, Heidelberg, Germany; Medical Center of the Johannes Gutenberg-University Mainz, Institute for Toxicology, Mainz, Germany
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13
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Fukunaga J, Nomura Y, Tanaka Y, Amano R, Tanaka T, Nakamura Y, Kawai G, Sakamoto T, Kozu T. The Runt domain of AML1 (RUNX1) binds a sequence-conserved RNA motif that mimics a DNA element. RNA (NEW YORK, N.Y.) 2013; 19:927-936. [PMID: 23709277 PMCID: PMC3683927 DOI: 10.1261/rna.037879.112] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/28/2013] [Indexed: 06/02/2023]
Abstract
AML1 (RUNX1) is a key transcription factor for hematopoiesis that binds to the Runt-binding double-stranded DNA element (RDE) of target genes through its N-terminal Runt domain. Aberrations in the AML1 gene are frequently found in human leukemia. To better understand AML1 and its potential utility for diagnosis and therapy, we obtained RNA aptamers that bind specifically to the AML1 Runt domain. Enzymatic probing and NMR analyses revealed that Apt1-S, which is a truncated variant of one of the aptamers, has a CACG tetraloop and two stem regions separated by an internal loop. All the isolated aptamers were found to contain the conserved sequence motif 5'-NNCCAC-3' and 5'-GCGMGN'N'-3' (M:A or C; N and N' form Watson-Crick base pairs). The motif contains one AC mismatch and one base bulged out. Mutational analysis of Apt1-S showed that three guanines of the motif are important for Runt binding as are the three guanines of RDE, which are directly recognized by three arginine residues of the Runt domain. Mutational analyses of the Runt domain revealed that the amino acid residues used for Apt1-S binding were similar to those used for RDE binding. Furthermore, the aptamer competed with RDE for binding to the Runt domain in vitro. These results demonstrated that the Runt domain of the AML1 protein binds to the motif of the aptamer that mimics DNA. Our findings should provide new insights into RNA function and utility in both basic and applied sciences.
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Affiliation(s)
- Junichi Fukunaga
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Saitama 362-0806, Japan
- CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan
| | - Yusuke Nomura
- CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
- Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Yoichiro Tanaka
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Saitama 362-0806, Japan
- CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan
- Facility for RI Research and Education, Instrumental Analysis Center, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
| | - Ryo Amano
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Taku Tanaka
- CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Yoshikazu Nakamura
- CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan
- Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Gota Kawai
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Taiichi Sakamoto
- CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Tomoko Kozu
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Saitama 362-0806, Japan
- CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan
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14
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Witham J, Ouboussad L, Lefevre PF. A NF-κB-dependent dual promoter-enhancer initiates the lipopolysaccharide-mediated transcriptional activation of the chicken lysozyme in macrophages. PLoS One 2013; 8:e59389. [PMID: 23533622 PMCID: PMC3606415 DOI: 10.1371/journal.pone.0059389] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 02/14/2013] [Indexed: 02/06/2023] Open
Abstract
The transcriptional activation of the chicken lysozyme gene (cLys) by lipopolysaccharide (LPS) in macrophages is dependent on transcription of a LPS-Inducible Non-Coding RNA (LINoCR) triggering eviction of the CCCTC-binding factor (CTCF) from a negative regulatory element upstream of the lysozyme transcription start site. LINoCR is transcribed from a promoter originally characterized as a hormone response enhancer in the oviduct. Herein, we report the characterization of this cis-regulatory element (CRE). In activated macrophages, a 60 bp region bound by NF-κB, AP1 and C/EBPβ controls this CRE, which is strictly dependent on NF-κB binding for its activity in luciferase assays. Moreover, the serine/threonine kinase IKKα, known to be recruited by NF-κB to NF-κB-dependent genes is found at the CRE and within the transcribing regions of both cLys and LINoCR. Such repartition suggests a simultaneous promoter and enhancer activity of this CRE, initiating cLys transcriptional activation and driving CTCF eviction. This recruitment was transient despite persistence of both cLys transcription and NF-κB binding to the CRE. Finally, comparing cLys with other LPS-inducible genes indicates that IKKα detection within transcribing regions can be correlated with the presence of the elongating form of RNA polymerase II or concentrated in the 3′ end of the gene.
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Affiliation(s)
- James Witham
- Section of Experimental Haematology, Leeds Institute of Molecular Medicine, University of Leeds, Wellcome Trust Brenner Building, St. James’s University Hospital, Leeds, United Kingdom
| | - Lylia Ouboussad
- Section of Experimental Haematology, Leeds Institute of Molecular Medicine, University of Leeds, Wellcome Trust Brenner Building, St. James’s University Hospital, Leeds, United Kingdom
| | - Pascal F. Lefevre
- Section of Experimental Haematology, Leeds Institute of Molecular Medicine, University of Leeds, Wellcome Trust Brenner Building, St. James’s University Hospital, Leeds, United Kingdom
- * E-mail:
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15
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Derbyshire N, White SJ, Bunka DHJ, Song L, Stead S, Tarbin J, Sharman M, Zhou D, Stockley PG. Toggled RNA aptamers against aminoglycosides allowing facile detection of antibiotics using gold nanoparticle assays. Anal Chem 2012; 84:6595-602. [PMID: 22793869 PMCID: PMC3413241 DOI: 10.1021/ac300815c] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 07/12/2012] [Indexed: 11/28/2022]
Abstract
We have used systematic evolution of ligands by exponential enrichment (SELEX) to isolate RNA aptamers against aminoglycoside antibiotics. The SELEX rounds were toggled against four pairs of aminoglycosides with the goal of isolating reagents that recognize conserved structural features. The resulting aptamers bind both of their selection targets with nanomolar affinities. They also bind the less structurally related targets, although they show clear specificity for this class of antibiotics. We show that this lack of aminoglycoside specificity is a common property of aptamers previously selected against single compounds and described as "specific". Broad target specificity aptamers would be ideal for sensors detecting the entire class of aminoglycosides. We have used ligand-induced aggregation of gold-nanoparticles coated with our aptamers as a rapid and sensitive assay for these compounds. In contrast to DNA aptamers, unmodified RNA aptamers cannot be used as the recognition ligand in this assay, whereas 2'-fluoro-pyrimidine derivatives work reliably. We discuss the possible application of these reagents as sensors for drug residues and the challenges for understanding the structural basis of aminoglycoside-aptamer recognition highlighted by the SELEX results.
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Affiliation(s)
- Nicola Derbyshire
- Astbury
Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds, LS2 9JT,
United Kingdom
| | - Simon J. White
- Astbury
Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds, LS2 9JT,
United Kingdom
| | - David H. J. Bunka
- Astbury
Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds, LS2 9JT,
United Kingdom
| | - Lei Song
- Astbury
Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds, LS2 9JT,
United Kingdom
| | - Sara Stead
- The Food and Environmental
Research Agency, Sand Hutton, Yorkshire, YO41 1LZ, United
Kingdom
| | - Jonathan Tarbin
- The Food and Environmental
Research Agency, Sand Hutton, Yorkshire, YO41 1LZ, United
Kingdom
| | - Matthew Sharman
- The Food and Environmental
Research Agency, Sand Hutton, Yorkshire, YO41 1LZ, United
Kingdom
| | - Dejian Zhou
- Astbury
Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds, LS2 9JT,
United Kingdom
| | - Peter G. Stockley
- Astbury
Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds, LS2 9JT,
United Kingdom
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16
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Blaum BS, Wünsche W, Benie AJ, Kusov Y, Peters H, Gauss-Müller V, Peters T, Sczakiel G. Functional binding of hexanucleotides to 3C protease of hepatitis A virus. Nucleic Acids Res 2012; 40:3042-55. [PMID: 22156376 PMCID: PMC3326307 DOI: 10.1093/nar/gkr1152] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 11/09/2011] [Accepted: 11/10/2011] [Indexed: 12/01/2022] Open
Abstract
Oligonucleotides as short as 6 nt in length have been shown to bind specifically and tightly to proteins and affect their biological function. Yet, sparse structural data are available for corresponding complexes. Employing a recently developed hexanucleotide array, we identified hexadeoxyribonucleotides that bind specifically to the 3C protease of hepatitis A virus (HAV 3C(pro)). Inhibition assays in vitro identified the hexanucleotide 5'-GGGGGT-3' (G(5)T) as a 3C(pro) protease inhibitor. Using (1)H NMR spectroscopy, G(5)T was found to form a G-quadruplex, which might be considered as a minimal aptamer. With the help of (1)H, (15)N-HSQC experiments the binding site for G(5)T was located to the C-terminal β-barrel of HAV 3C(pro). Importantly, the highly conserved KFRDI motif, which has previously been identified as putative viral RNA binding site, is not part of the G(5)T-binding site, nor does G(5)T interfere with the binding of viral RNA. Our findings demonstrate that sequence-specific nucleic acid-protein interactions occur with oligonucleotides as small as hexanucleotides and suggest that these compounds may be of pharmaceutical relevance.
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Affiliation(s)
- Bärbel S. Blaum
- Institute of Chemistry, Institute of Molecular Medicine, Institute for Virology and Cell Biology and Institute for Biochemistry, University of Luebeck, Center for Structural and Cell Biology in Medicine (CSCM), Ratzeburger Allee 160, D-23538 Luebeck, Germany
| | - Winfried Wünsche
- Institute of Chemistry, Institute of Molecular Medicine, Institute for Virology and Cell Biology and Institute for Biochemistry, University of Luebeck, Center for Structural and Cell Biology in Medicine (CSCM), Ratzeburger Allee 160, D-23538 Luebeck, Germany
| | - Andrew J. Benie
- Institute of Chemistry, Institute of Molecular Medicine, Institute for Virology and Cell Biology and Institute for Biochemistry, University of Luebeck, Center for Structural and Cell Biology in Medicine (CSCM), Ratzeburger Allee 160, D-23538 Luebeck, Germany
| | - Yuri Kusov
- Institute of Chemistry, Institute of Molecular Medicine, Institute for Virology and Cell Biology and Institute for Biochemistry, University of Luebeck, Center for Structural and Cell Biology in Medicine (CSCM), Ratzeburger Allee 160, D-23538 Luebeck, Germany
| | - Hannelore Peters
- Institute of Chemistry, Institute of Molecular Medicine, Institute for Virology and Cell Biology and Institute for Biochemistry, University of Luebeck, Center for Structural and Cell Biology in Medicine (CSCM), Ratzeburger Allee 160, D-23538 Luebeck, Germany
| | - Verena Gauss-Müller
- Institute of Chemistry, Institute of Molecular Medicine, Institute for Virology and Cell Biology and Institute for Biochemistry, University of Luebeck, Center for Structural and Cell Biology in Medicine (CSCM), Ratzeburger Allee 160, D-23538 Luebeck, Germany
| | - Thomas Peters
- Institute of Chemistry, Institute of Molecular Medicine, Institute for Virology and Cell Biology and Institute for Biochemistry, University of Luebeck, Center for Structural and Cell Biology in Medicine (CSCM), Ratzeburger Allee 160, D-23538 Luebeck, Germany
| | - Georg Sczakiel
- Institute of Chemistry, Institute of Molecular Medicine, Institute for Virology and Cell Biology and Institute for Biochemistry, University of Luebeck, Center for Structural and Cell Biology in Medicine (CSCM), Ratzeburger Allee 160, D-23538 Luebeck, Germany
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17
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Feng H, Beck J, Nassal M, Hu KH. A SELEX-screened aptamer of human hepatitis B virus RNA encapsidation signal suppresses viral replication. PLoS One 2011; 6:e27862. [PMID: 22125633 PMCID: PMC3220704 DOI: 10.1371/journal.pone.0027862] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 10/26/2011] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND The specific interaction between hepatitis B virus (HBV) polymerase (P protein) and the ε RNA stem-loop on pregenomic (pg) RNA is crucial for viral replication. It triggers both pgRNA packaging and reverse transcription and thus represents an attractive antiviral target. RNA decoys mimicking ε in P protein binding but not supporting replication might represent novel HBV inhibitors. However, because generation of recombinant enzymatically active HBV polymerase is notoriously difficult, such decoys have as yet not been identified. METHODOLOGY/PRINCIPAL FINDINGS Here we used a SELEX approach, based on a new in vitro reconstitution system exploiting a recombinant truncated HBV P protein (miniP), to identify potential ε decoys in two large ε RNA pools with randomized upper stem. Selection of strongly P protein binding RNAs correlated with an unexpected strong enrichment of A residues. Two aptamers, S6 and S9, displayed particularly high affinity and specificity for miniP in vitro, yet did not support viral replication when part of a complete HBV genome. Introducing S9 RNA into transiently HBV producing HepG2 cells strongly suppressed pgRNA packaging and DNA synthesis, indicating the S9 RNA can indeed act as an ε decoy that competitively inhibits P protein binding to the authentic ε signal on pgRNA. CONCLUSIONS/SIGNIFICANCE This study demonstrates the first successful identification of human HBV ε aptamers by an in vitro SELEX approach. Effective suppression of HBV replication by the S9 aptamer provides proof-of-principle for the ability of ε decoy RNAs to interfere with viral P-ε complex formation and suggests that S9-like RNAs may further be developed into useful therapeutics against chronic hepatitis B.
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Affiliation(s)
- Hui Feng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Jürgen Beck
- University Hospital Freiburg, Internal Medicine II/Molecular Biology, Freiburg, Germany
| | - Michael Nassal
- University Hospital Freiburg, Internal Medicine II/Molecular Biology, Freiburg, Germany
| | - Kang-hong Hu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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18
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Bunka DHJ, Lane SW, Lane CL, Dykeman EC, Ford RJ, Barker AM, Twarock R, Phillips SEV, Stockley PG. Degenerate RNA packaging signals in the genome of Satellite Tobacco Necrosis Virus: implications for the assembly of a T=1 capsid. J Mol Biol 2011; 413:51-65. [PMID: 21839093 DOI: 10.1016/j.jmb.2011.07.063] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 07/20/2011] [Accepted: 07/26/2011] [Indexed: 11/26/2022]
Abstract
Using a recombinant, T=1 Satellite Tobacco Necrosis Virus (STNV)-like particle expressed in Escherichia coli, we have established conditions for in vitro disassembly and reassembly of the viral capsid. In vivo assembly is dependent on the presence of the coat protein (CP) N-terminal region, and in vitro assembly requires RNA. Using immobilised CP monomers under reassembly conditions with "free" CP subunits, we have prepared a range of partially assembled CP species for RNA aptamer selection. SELEX directed against the RNA-binding face of the STNV CP resulted in the isolation of several clones, one of which (B3) matches the STNV-1 genome in 16 out of 25 nucleotide positions, including across a statistically significant 10/10 stretch. This 10-base region folds into a stem-loop displaying the motif ACAA and has been shown to bind to STNV CP. Analysis of the other aptamer sequences reveals that the majority can be folded into stem-loops displaying versions of this motif. Using a sequence and secondary structure search motif to analyse the genomic sequence of STNV-1, we identified 30 stem-loops displaying the sequence motif AxxA. The implication is that there are many stem-loops in the genome carrying essential recognition features for binding STNV CP. Secondary structure predictions of the genomic RNA using Mfold showed that only 8 out of 30 of these stem-loops would be formed in the lowest-energy structure. These results are consistent with an assembly mechanism based on kinetically driven folding of the RNA.
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Affiliation(s)
- David H J Bunka
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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