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] [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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Kumagai K, Okubo H, Amano R, Kozu T, Ochiai M, Horiuchi M, Sakamoto T. Selection of aptamers using β-1,3-glucan recognition protein-tagged proteins and curdlan beads. J Biochem 2023; 174:433-440. [PMID: 37500079 DOI: 10.1093/jb/mvad059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/22/2023] [Accepted: 07/26/2023] [Indexed: 07/29/2023] Open
Abstract
RNA aptamersare nucleic acids that are obtained using the systematic evolution of ligands by exponential enrichment (SELEX) method. When using conventional selection methods to immobilize target proteins on matrix beads using protein tags, sequences are obtained that bind not only to the target proteins but also to the protein tags and matrix beads. In this study, we performed SELEX using β-1,3-glucan recognition protein (GRP)-tags and curdlan beads to immobilize the acute myeloid leukaemia 1 (AML1) Runt domain (RD) and analysed the enrichment of aptamers using high-throughput sequencing. Comparison of aptamer enrichment using the GRP-tag and His-tag suggested that aptamers were enriched using the GRP-tag as well as using the His-tag. Furthermore, surface plasmon resonance analysis revealed that the aptamer did not bind to the GRP-tag and that the conjugation of the GRP-tag to RD weakened the interaction between the aptamer and RD. The GRP-tag could have acted as a competitor to reduce weakly bound RNAs. Therefore, the affinity system of the GRP-tagged proteins and curdlan beads is suitable for obtaining specific aptamers using SELEX.
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Key Words
- SELEX.Abbreviations:
AML1, acute myeloid leukaemia 1; βGRP, β-1,3-glucan recognition protein; GST, glutathione S-transferase; His-tag, poly histidine tag; HTS, high-throughput sequencing; MBP, maltose-binding protein; RD, Runt domain; RUNX1, RUNX family transcription factor 1; SELEX, systematic evolution of ligands by exponential enrichment; SPR, surface plasmon resonance
- aptamer
- curdlan
- βGRP
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Affiliation(s)
- Kazuyuki Kumagai
- Department of Life Science, Faculty of Advanced Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Hiroki Okubo
- Department of Life Science, Faculty of Advanced Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Ryo Amano
- Department of Life Science, Faculty of Advanced Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Tomoko Kozu
- Research Institute for Clinical Oncology, Saitama Cancer Center, 780 Komuro, Ina, Kitaadachi, Saitama 362-0806, Japan
| | - Masanori Ochiai
- Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo 060-0819, Japan
| | - Masataka Horiuchi
- Faculty of Pharmaceutical Science, Health Sciences University of Hokkaido, 1757 Kanazawa, Toubetsu, Ishikari, Hokkaido 061-0293, Japan
| | - Taiichi Sakamoto
- Department of Life Science, Faculty of Advanced Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
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3
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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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4
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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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5
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Nomura Y, Yamazaki K, Amano R, Takada K, Nagata T, Kobayashi N, Tanaka Y, Fukunaga J, Katahira M, Kozu T, Nakamura Y, Haishima Y, Torigoe H, Sakamoto T. Conjugation of two RNA aptamers improves binding affinity to AML1 Runt domain. J Biochem 2017; 162:431-436. [PMID: 28992043 DOI: 10.1093/jb/mvx049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 06/19/2017] [Indexed: 12/22/2022] Open
Abstract
To develop a high-affinity aptamer against AML1 Runt domain, two aptamers were conjugated based on their structural information. The newly designed aptamer Apt14 was generated by the conjugation of two RNA aptamers (Apt1 and Apt4) obtained by SELEX against AML1 Runt domain, resulting in improvement in its binding performance. The residues of AML1 Runt domain in contact with Apt14 were predicted in silico and confirmed by mutation and NMR analyses. It was suggested that the conjugated internal loop renders additional contacts and is responsible for the enhancement in the binding affinity. Conjugation of two aptamers that bind to different sites of the target protein is a facile and robust strategy to develop an aptamer with higher performance.
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Affiliation(s)
- Yusuke Nomura
- Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku 162-8601, Tokyo, Japan.,Division of Medical Devices, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Kaori Yamazaki
- Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku 162-8601, Tokyo, 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
| | - Kenta Takada
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Takashi Nagata
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Naohiro Kobayashi
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoichiro Tanaka
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Saitama 362-0806, Japan
| | - Junichi Fukunaga
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Saitama 362-0806, Japan
| | - Masato Katahira
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Tomoko Kozu
- Research Institute for Clinical Oncology, Saitama Cancer Center, Ina, Saitama 362-0806, Japan
| | - Yoshikazu Nakamura
- RIBOMIC Inc, 3-16-13 Shirokanedai, Minato-ku, Tokyo 108-0071, Japan.,Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Yuji Haishima
- Division of Medical Devices, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Hidetaka Torigoe
- Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku 162-8601, Tokyo, 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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6
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Amano R, Aoki K, Miyakawa S, Nakamura Y, Kozu T, Kawai G, Sakamoto T. NMR monitoring of the SELEX process to confirm enrichment of structured RNA. Sci Rep 2017; 7:283. [PMID: 28325909 PMCID: PMC5428055 DOI: 10.1038/s41598-017-00273-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/15/2017] [Indexed: 01/20/2023] Open
Abstract
RNA aptamers are RNA molecules that bind to a target molecule with high affinity and specificity using uniquely-folded tertiary structures. RNA aptamers are selected from an RNA pool typically comprising up to 1015 different sequences generated by iterative steps of selection and amplification known as Systematic Evolution of Ligands by EXponential enrichment (SELEX). Over several rounds of SELEX, the diversity of the RNA pool decreases and the aptamers are enriched. Hence, monitoring of the enrichment of these RNA pools is critical for the successful selection of aptamers, and several methods for monitoring them have been developed. In this study, we measured one-dimensional imino proton NMR spectra of RNA pools during SELEX. The spectrum of the initial RNA pool indicates that the RNAs adopt tertiary structures. The structural diversity of the RNA pools was shown to depend highly on the design of the primer-binding sequence. Furthermore, we demonstrate that enrichment of RNA aptamers can be monitored using NMR. The RNA pools can be recovered from the NMR tube after measurement of NMR spectra. We also can monitor target binding in the NMR tubes. Thus, we propose using NMR to monitor the enrichment of structured aptamers during the SELEX process.
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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
| | - Kazuteru Aoki
- Ribomic Inc., 3-16-13 Shirokanedai, Minato-ku, Tokyo, 108-0071, Japan
| | - Shin Miyakawa
- Ribomic Inc., 3-16-13 Shirokanedai, Minato-ku, Tokyo, 108-0071, Japan
| | - Yoshikazu Nakamura
- Ribomic Inc., 3-16-13 Shirokanedai, Minato-ku, Tokyo, 108-0071, Japan
- Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108-8639, Japan
| | - Tomoko Kozu
- Research Institute for Clinical Oncology, Saitama Cancer Center, 818 Komuro, Ina, Kitaadachi-gun, Saitama, 362-0806, 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
- 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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7
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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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8
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Bjerregaard N, Andreasen PA, Dupont DM. Expected and unexpected features of protein-binding RNA aptamers. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:744-757. [PMID: 27173731 DOI: 10.1002/wrna.1360] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 04/03/2016] [Accepted: 04/04/2016] [Indexed: 12/28/2022]
Abstract
RNA molecules with high affinity to specific proteins can be isolated from libraries of up to 1016 different RNA sequences by systematic evolution of ligands by exponential enrichment (SELEX). These so-called protein-binding RNA aptamers are often interesting, e.g., as modulators of protein function for therapeutic use, for probing the conformations of proteins, for studies of basic aspects of nucleic acid-protein interactions, etc. Studies on the interactions between RNA aptamers and proteins display a number of expected and unexpected features, including the chemical nature of the interacting RNA-protein surfaces, the conformation of protein-bound aptamer versus free aptamer, the conformation of aptamer-bound protein versus free protein, and the effects of aptamers on protein function. Here, we review current insights into the details of RNA aptamer-protein interactions. WIREs RNA 2016, 7:744-757. doi: 10.1002/wrna.1360 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Nils Bjerregaard
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Peter A Andreasen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Daniel M Dupont
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
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9
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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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10
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Mondragón E, Maher LJ. RNA aptamer inhibitors of a restriction endonuclease. Nucleic Acids Res 2015; 43:7544-55. [PMID: 26184872 PMCID: PMC4551934 DOI: 10.1093/nar/gkv702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 06/29/2015] [Indexed: 11/18/2022] Open
Abstract
Restriction endonucleases (REases) recognize and cleave short palindromic DNA sequences, protecting bacterial cells against bacteriophage infection by attacking foreign DNA. We are interested in the potential of folded RNA to mimic DNA, a concept that might be applied to inhibition of DNA-binding proteins. As a model system, we sought RNA aptamers against the REases BamHI, PacI and KpnI using systematic evolution of ligands by exponential enrichment (SELEX). After 20 rounds of selection under different stringent conditions, we identified the 10 most enriched RNA aptamers for each REase. Aptamers were screened for binding and specificity, and assayed for REase inhibition. We obtained eight high-affinity (Kd ∼12-30 nM) selective competitive inhibitors (IC50 ∼20-150 nM) for KpnI. Predicted RNA secondary structures were confirmed by in-line attack assay and a 38-nt derivative of the best anti-KpnI aptamer was sufficient for inhibition. These competitive inhibitors presumably act as KpnI binding site analogs, but lack the primary consensus KpnI cleavage sequence and are not cleaved by KpnI, making their potential mode of DNA mimicry fascinating. Anti-REase RNA aptamers could have value in studies of REase mechanism and may give clues to a code for designing RNAs that competitively inhibit DNA binding proteins including transcription factors.
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Affiliation(s)
- Estefanía Mondragón
- Neurobiology of Disease track, Mayo Graduate School, 200 First St SW, Rochester, MN 55905, USA
| | - L James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905, USA
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