1
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Singh G, Monga V. Peptide Nucleic Acids: Recent Developments in the Synthesis and Backbone Modifications. Bioorg Chem 2023; 141:106860. [PMID: 37748328 DOI: 10.1016/j.bioorg.2023.106860] [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: 04/12/2023] [Revised: 09/07/2023] [Accepted: 09/09/2023] [Indexed: 09/27/2023]
Abstract
Nucleic acid represents the ideal drug candidate for protein targets that are hard to target or against which drug development is not easy. Peptide nucleic acids (PNAs) are synthesized by attaching modified peptide backbones generally derived from repetitive N-2-aminoethyl glycine units in place of the regular phosphodiester backbone and represent synthetic impersonator of nucleic acids that offers an exciting research field due to their fascinating spectrum of biotechnological, diagnostic and potential therapeutic applications. The semi-rigid peptide nucleic acid backbone serves as a nearly-perfect template for attaching complimentary base pairs on DNA or RNA in a sequence-dependent manner as described by Watson-Crick models. PNAs and their analogues are endowed with exceptionally high affinity and specificity for receptor sites, essentially due to their polyamide backbone's uncharged and flexible nature. The present review compiled various strategies to modify the polypeptide backbone for improving the target selectivity and stability of the PNAs in the body. The investigated biological activities carried out on PNAs have also been summarized in the present review.
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Affiliation(s)
- Gurpreet Singh
- Department of Pharmaceutical Chemistry, ISF College of Pharmacy, GT Road, Ghal Kalan, Moga 142001, Punjab, India
| | - Vikramdeep Monga
- Department of Pharmaceutical Sciences and Natural Products, Central University of Punjab, VPO-Ghudda, Bathinda 151401, Punjab, India.
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2
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Talbott JM, Tessier BR, Harding EE, Walby GD, Hess KJ, Baskevics V, Katkevics M, Rozners E, MacKay JA. Improved Triplex-Forming Isoorotamide PNA Nucleobases for A-U Recognition of RNA Duplexes. Chemistry 2023; 29:e202302390. [PMID: 37647091 DOI: 10.1002/chem.202302390] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/24/2023] [Accepted: 08/30/2023] [Indexed: 09/01/2023]
Abstract
Four new isoorotamide (Io)-containing PNA nucleobases have been designed for A-U recognition of double helical RNA. New PNA monomers were prepared efficiently and incorporated into PNA nonamers for binding A-U in a PNA:RNA2 triplex. Isothermal titration calorimetry and UV thermal melting experiments revealed slightly improved binding affinity for singly modified PNA compared to known A-binding nucleobases. Molecular dynamics simulations provided further insights into binding of Io bases in the triple helix. Together, the data revealed interesting insights into binding modes including the notion that three Hoogsteen hydrogen bonds are unnecessary for strong selective binding of an extended nucleobase. Cationic monomer Io8 additionally gave the highest affinity observed for an A-binding nucleobase to date. These results will help inform future nucleobase design toward the goal of recognizing any sequence of double helical RNA.
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Affiliation(s)
- John M Talbott
- Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, PA 17022, USA
| | - Brandon R Tessier
- Department of Chemistry, Binghamton University, Binghamton, NY 13902, USA
| | - Emily E Harding
- Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, PA 17022, USA
| | - Grant D Walby
- Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, PA 17022, USA
| | - Kyle J Hess
- Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, PA 17022, USA
| | | | - Martins Katkevics
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, Binghamton, NY 13902, USA
| | - James A MacKay
- Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, PA 17022, USA
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3
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Mikame Y, Yamayoshi A. Recent Advancements in Development and Therapeutic Applications of Genome-Targeting Triplex-Forming Oligonucleotides and Peptide Nucleic Acids. Pharmaceutics 2023; 15:2515. [PMID: 37896275 PMCID: PMC10609763 DOI: 10.3390/pharmaceutics15102515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/15/2023] [Accepted: 10/19/2023] [Indexed: 10/29/2023] Open
Abstract
Recent developments in artificial nucleic acid and drug delivery systems present possibilities for the symbiotic engineering of therapeutic oligonucleotides, such as antisense oligonucleotides (ASOs) and small interfering ribonucleic acids (siRNAs). Employing these technologies, triplex-forming oligonucleotides (TFOs) or peptide nucleic acids (PNAs) can be applied to the development of symbiotic genome-targeting tools as well as a new class of oligonucleotide drugs, which offer conceptual advantages over antisense as the antigene target generally comprises two gene copies per cell rather than multiple copies of mRNA that are being continually transcribed. Further, genome editing by TFOs or PNAs induces permanent changes in the pathological genes, thus facilitating the complete cure of diseases. Nuclease-based gene-editing tools, such as zinc fingers, CRISPR-Cas9, and TALENs, are being explored for therapeutic applications, although their potential off-target, cytotoxic, and/or immunogenic effects may hinder their in vivo applications. Therefore, this review is aimed at describing the ongoing progress in TFO and PNA technologies, which can be symbiotic genome-targeting tools that will cause a near-future paradigm shift in drug development.
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Affiliation(s)
- Yu Mikame
- Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyomachi, Nagasaki 852-8521, Japan
| | - Asako Yamayoshi
- Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyomachi, Nagasaki 852-8521, Japan
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4
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López-Tena M, Chen SK, Winssinger N. Supernatural: Artificial Nucleobases and Backbones to Program Hybridization-Based Assemblies and Circuits. Bioconjug Chem 2023; 34:111-123. [PMID: 35856656 DOI: 10.1021/acs.bioconjchem.2c00292] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The specificity and predictability of hybridization make oligonucleotides a powerful platform to program assemblies and networks with logic-gated responses, an area of research which has grown into a field of its own. While the field has capitalized on the commercial availability of DNA oligomers with its four canonical nucleobases, there are opportunities to extend the capabilities of the hardware with unnatural nucleobases and other backbones. This Topical Review highlights nucleobases that favor hybridizations that are empowering for assemblies and networks as well as two chiral XNAs than enable orthogonal hybridization networks.
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Affiliation(s)
- Miguel López-Tena
- University of Geneva, Department of Organic Chemistry, Faculty of Science, NCCR Chemical Biology, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland
| | - Si-Kai Chen
- University of Geneva, Department of Organic Chemistry, Faculty of Science, NCCR Chemical Biology, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland
| | - Nicolas Winssinger
- University of Geneva, Department of Organic Chemistry, Faculty of Science, NCCR Chemical Biology, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland
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5
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Ryan CA, Baskevics V, Katkevics M, Rozners E. 2-Guanidyl pyridine PNA nucleobase for triple-helical Hoogsteen recognition of cytosine in double-stranded RNA. Chem Commun (Camb) 2022; 58:7148-7151. [PMID: 35666682 DOI: 10.1039/d2cc02615e] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In triplex-forming peptide nucleic acid, a novel 2-guanidyl pyridine nucleobase (V) enables recognition of up to two cytosine interruptions in polypurine tracts of dsRNA by engaging the entire Hoogsteen face of C-G base pair. Ab initio and molecular dynamics simulations provided insights into H-bonding interactions that stabilized V·C-G triplets. Our results provided insights for future design of improved nucleobases, which is an important step towards the ultimate goal of recognition of any sequence of dsRNA.
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Affiliation(s)
- Christopher A Ryan
- Department of Chemistry, Binghamton University, Binghamton, NY 13902, USA.
| | | | - Martins Katkevics
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, Binghamton, NY 13902, USA.
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6
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Sato Y, Miura H, Tanabe T, Okeke CU, Kikuchi A, Nishizawa S. Fluorescence Sensing of the Panhandle Structure of the Influenza A Virus RNA Promoter by Thiazole Orange Base Surrogate-Carrying Peptide Nucleic Acid Conjugated with Small Molecule. Anal Chem 2022; 94:7814-7822. [PMID: 35604144 DOI: 10.1021/acs.analchem.1c05488] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have developed a new class of triplex-forming peptide nucleic acid (PNA)-based fluorogenic probes for sensing of the panhandle structure of the influenza A virus (IAV) RNA promoter region. Here, a small molecule (DPQ) capable of selectively binding to the internal loop structure was conjugated with triplex-forming forced intercalation of the thiazole orange (tFIT) probe with natural PNA nucleobases. The resulting conjugate, tFIT-DPQ, showed a significant light-up response (83-fold) upon strong (Kd = 107 nM) and structure-selective binding to the IAV RNA promoter region under physiological conditions (pH 7.0, 100 mM NaCl). We demonstrated the conjugation of these two units through the suitable spacer was key to show useful binding and fluorogenic signaling functions. tFIT-DPQ facilitated the sensitive and selective detection of IAV RNA based on its binding to the promoter region. Furthermore, we found that tFIT-DPQ could work as a sensitive indicator for screening of test compounds targeting the IAV RNA promoter region in the fluorescence indicator displacement assay.
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Affiliation(s)
- Yusuke Sato
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Hiromasa Miura
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Takaaki Tanabe
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Chioma Uche Okeke
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Akiko Kikuchi
- Department of Kampo and Integrative Medicine, Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan
| | - Seiichi Nishizawa
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
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7
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NISHIZAWA S, SATO T, LEE ETT, SAKAMOTO N, CHIBA T, TANABE T, YOSHINO Y, TAKAHASHI Y, SATO Y. Triplex-Forming Peptide Nucleic Acid Probes Having Cyanine Base Surrogates for Fluorogenic Sensing of Double-Stranded RNA. BUNSEKI KAGAKU 2022. [DOI: 10.2116/bunsekikagaku.71.133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Seiichi NISHIZAWA
- Department of Chemistry, Graduate School of Science, Tohoku University
| | - Takaya SATO
- Department of Chemistry, Graduate School of Science, Tohoku University
| | | | - Naonari SAKAMOTO
- Department of Chemistry, Graduate School of Science, Tohoku University
| | - Toshiki CHIBA
- Department of Chemistry, Graduate School of Science, Tohoku University
| | - Takaaki TANABE
- Department of Chemistry, Graduate School of Science, Tohoku University
| | - Yukina YOSHINO
- Department of Chemistry, Graduate School of Science, Tohoku University
| | - Yuki TAKAHASHI
- Department of Chemistry, Graduate School of Science, Tohoku University
| | - Yusuke SATO
- Department of Chemistry, Graduate School of Science, Tohoku University
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8
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NISHIZAWA S, LEE ETT, YOSHINO Y, YAJIMA S, ROKUGAWA M, SATO Y. Molecular Design of Fluorogenic Probes for Targeting rRNA: Indicator in FID Assay and Dye for Imaging of Nucleolar RNA in Living Cells. BUNSEKI KAGAKU 2021. [DOI: 10.2116/bunsekikagaku.70.703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Seiichi NISHIZAWA
- Department of Chemistry, Graduate School of Sciences, Tohoku University
| | | | - Yukina YOSHINO
- Department of Chemistry, Graduate School of Sciences, Tohoku University
| | - Sayaka YAJIMA
- Department of Chemistry, Graduate School of Sciences, Tohoku University
| | - Masafumi ROKUGAWA
- Department of Chemistry, Graduate School of Sciences, Tohoku University
| | - Yusuke SATO
- Department of Chemistry, Graduate School of Sciences, Tohoku University
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9
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Zhan X, Deng L, Chen G. Mechanisms and applications of peptide nucleic acids selectively binding to double-stranded RNA. Biopolymers 2021; 113:e23476. [PMID: 34581432 DOI: 10.1002/bip.23476] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 12/11/2022]
Abstract
RNAs form secondary structures containing double-stranded base paired regions and single-stranded regions. Probing, detecting and modulating RNA structures and dynamics requires the development of molecular sensors that can differentiate the sequence and structure of RNAs present in viruses and cells, as well as in extracellular space. In this review, we summarize the recent progress on the development of chemically modified peptide nucleic acids (PNAs) for the selective recognition of double-stranded RNA (dsRNA) sequences over both single-stranded RNA (ssRNA) and double-stranded DNA (dsDNA) sequences. We also briefly discuss the applications of sequence-specific dsRNA-binding PNAs in sensing and stabilizing dsRNA structures and inhibiting dsRNA-protein interactions.
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Affiliation(s)
- Xuan Zhan
- School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, China
| | - Liping Deng
- School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, China
| | - Gang Chen
- School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen, China
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10
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Sato T, Sato Y, Nishizawa S. Spectroscopic, thermodynamic and kinetic analysis of selective triplex formation by peptide nucleic acid with double-stranded RNA over its DNA counterpart. Biopolymers 2021; 113:e23474. [PMID: 34478151 DOI: 10.1002/bip.23474] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 07/11/2021] [Accepted: 08/17/2021] [Indexed: 12/27/2022]
Abstract
Unlike conventional triplex-forming oligonucleotide (TFO), triplex-forming peptide nucleic acid (PNA) can tightly bind with double-stranded RNA (dsRNA) than double-stranded DNA (dsDNA). Here, we performed spectroscopic, thermodynamic and kinetic experiments for triplex formation by PNA to examine different binding behaviors between PNA - dsRNA and PNA - dsDNA triplexes. We found 9-mer PNA (cytosine content of 66%) formed the thermally stable triplex with dsRNA compared to dsDNA over a wide range of pH (5.5-8.0), salt concentration (50-500 mM NaCl). Both the calorimetric binding constant and the association rate constant for dsRNA were larger than those for dsDNA, indicating the favorable association process for the PNA - dsRNA triplex formation. Comparison with the DNA/RNA heteroduplexes revealed that the DNA strand was detrimental to the triplex stability for PNA, a contrasting result for conventional TFO. The keys underlying the difference in the triplex formation of PNA with different duplexes appear to be the conformational adoptability and the geometric compatibility of PNA to fit the deep, narrow major groove of dsRNA and the helical rigidity difference of the duplexes. Our results emphasize the importance of both the sugar puckering of the duplex and the appropriate conformational flexibility of PNA for the triplex formation.
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Affiliation(s)
- Takaya Sato
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Yusuke Sato
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Seiichi Nishizawa
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
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11
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Brodyagin N, Katkevics M, Kotikam V, Ryan CA, Rozners E. Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications. Beilstein J Org Chem 2021; 17:1641-1688. [PMID: 34367346 PMCID: PMC8313981 DOI: 10.3762/bjoc.17.116] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/28/2021] [Indexed: 12/23/2022] Open
Abstract
Peptide nucleic acid (PNA) is arguably one of the most successful DNA mimics, despite a most dramatic departure from the native structure of DNA. The present review summarizes 30 years of research on PNA's chemistry, optimization of structure and function, applications as probes and diagnostics, and attempts to develop new PNA therapeutics. The discussion starts with a brief review of PNA's binding modes and structural features, followed by the most impactful chemical modifications, PNA enabled assays and diagnostics, and discussion of the current state of development of PNA therapeutics. While many modifications have improved on PNA's binding affinity and specificity, solubility and other biophysical properties, the original PNA is still most frequently used in diagnostic and other in vitro applications. Development of therapeutics and other in vivo applications of PNA has notably lagged behind and is still limited by insufficient bioavailability and difficulties with tissue specific delivery. Relatively high doses are required to overcome poor cellular uptake and endosomal entrapment, which increases the risk of toxicity. These limitations remain unsolved problems waiting for innovative chemistry and biology to unlock the full potential of PNA in biomedical applications.
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Affiliation(s)
- Nikita Brodyagin
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Martins Katkevics
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia
| | - Venubabu Kotikam
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Christopher A Ryan
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
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12
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Sugimoto N, Endoh T, Takahashi S, Tateishi-Karimata H. Chemical Biology of Double Helical and Non-Double Helical Nucleic Acids: “To B or Not To B, That Is the Question”. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210131] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 17-1-20 Minatojima-minamimachi, Kobe, Hyogo 650-0047, Japan
- Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, 17-1-20 Minatojima-minamimachi, Kobe, Hyogo 650-0047, Japan
| | - Tamaki Endoh
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 17-1-20 Minatojima-minamimachi, Kobe, Hyogo 650-0047, Japan
| | - Shuntaro Takahashi
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 17-1-20 Minatojima-minamimachi, Kobe, Hyogo 650-0047, Japan
| | - Hisae Tateishi-Karimata
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 17-1-20 Minatojima-minamimachi, Kobe, Hyogo 650-0047, Japan
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13
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Perera JDR, Carufe KEW, Glazer PM. Peptide nucleic acids and their role in gene regulation and editing. Biopolymers 2021; 112:e23460. [PMID: 34129732 DOI: 10.1002/bip.23460] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 05/27/2021] [Accepted: 06/01/2021] [Indexed: 12/19/2022]
Abstract
The unique properties of peptide nucleic acid (PNA) makes it a desirable candidate to be used in therapeutic and biotechnological interventions. It has been broadly utilized for numerous applications, with a major focus in regulation of gene expression, and more recently in gene editing. While the classic PNA design has mainly been employed to date, chemical modifications of the PNA backbone and nucleobases provide an avenue to advance the technology further. This review aims to discuss the recent developments in PNA based gene manipulation techniques and the use of novel chemical modifications to improve the current state of PNA mediated gene targeting.
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Affiliation(s)
- J Dinithi R Perera
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Kelly E W Carufe
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Peter M Glazer
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
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14
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Liang X, Liu M, Komiyama M. Recognition of Target Site in Various Forms of DNA and RNA by Peptide Nucleic Acid (PNA): From Fundamentals to Practical Applications. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210086] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Xingguo Liang
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, P. R. China
- Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, P. R. China
| | - Mengqin Liu
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, P. R. China
| | - Makoto Komiyama
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, P. R. China
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15
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Ryan CA, Brodyagin N, Lok J, Rozners E. The 2-Aminopyridine Nucleobase Improves Triple-Helical Recognition of RNA and DNA When Used Instead of Pseudoisocytosine in Peptide Nucleic Acids. Biochemistry 2021; 60:1919-1925. [PMID: 34097400 DOI: 10.1021/acs.biochem.1c00275] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Pseudoisocytosine (J), a neutral analogue of protonated cytosine, is currently the gold standard modified nucleobase in peptide nucleic acids (PNAs) for the formation of J·G-C triplets that are stable at physiological pH. This study shows that triple-helical recognition of RNA and DNA is significantly improved by using 2-aminopyridine (M) instead of J. The positively charged M forms 3-fold stronger M+·G-C triplets than J with uncompromised sequence selectivity. Replacement of six Js with Ms in a PNA 9-mer increased its binding affinity by ∼2 orders of magnitude. M-modified PNAs prefer binding double-stranded RNA over DNA and disfavor off-target binding to single-stranded nucleic acids. Taken together, the results show that M is a promising modified nucleobase that significantly improves triplex-forming PNAs and may provide breakthrough developments for therapeutic and biotechnology applications.
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Affiliation(s)
- Christopher A Ryan
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Nikita Brodyagin
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Justin Lok
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
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16
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Brodyagin N, Kumpina I, Applegate J, Katkevics M, Rozners E. Pyridazine Nucleobase in Triplex-Forming PNA Improves Recognition of Cytosine Interruptions of Polypurine Tracts in RNA. ACS Chem Biol 2021; 16:872-881. [PMID: 33881836 DOI: 10.1021/acschembio.1c00044] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Sequence specific recognition of regulatory noncoding RNAs would open new possibilities for fundamental science and medicine. However, molecular recognition of such complex double-stranded RNA (dsRNA) structures remains a formidable problem. Recently, we discovered that peptide nucleic acids (PNAs) form an unusually stable and sequence-specific triple helix with dsRNA. Triplex-forming PNAs could become universal tools for recognition of noncoding dsRNAs but are limited by the requirement of polypurine tracts in target RNAs as only purines form stable Hoogsteen hydrogen bonded base triplets. Herein, we systematically surveyed simple nitrogen heterocycles PN as modified nucleobases for recognition of cytosine in PN*C-G triplets. We found that a 3-pyridazinyl nucleobase formed significantly more stable PN*C-G triplets than other heterocycles including the pyrimidin-2-one previously used by us and others for recognition of cytosine interruptions in polypurine tracts of PNA-dsRNA triplexes. Our results improve triple helical recognition of dsRNA and provide insights for future development of new nucleobases to expand the sequence scope of noncoding dsRNAs that can be targeted by triplex-forming PNAs.
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Affiliation(s)
- Nikita Brodyagin
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Ilze Kumpina
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia
| | - Justin Applegate
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Martins Katkevics
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
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17
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Topham CM, Smith JC. Peptide nucleic acid Hoogsteen strand linker design for major groove recognition of DNA thymine bases. J Comput Aided Mol Des 2021; 35:355-369. [PMID: 33624202 DOI: 10.1007/s10822-021-00375-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 02/03/2021] [Indexed: 10/22/2022]
Abstract
Sequence-specific targeting of double-stranded DNA and non-coding RNA via triple-helix-forming peptide nucleic acids (PNAs) has attracted considerable attention in therapeutic, diagnostic and nanotechnological fields. An E-base (3-oxo-2,3-dihydropyridazine), attached to the polyamide backbone of a PNA Hoogsteen strand by a side-chain linker molecule, is typically used in the hydrogen bond recognition of the 4-oxo group of thymine and uracil nucleic acid bases in the major groove. We report on the application of quantum chemical computational methods, in conjunction with spatial constraints derived from the experimental structure of a homopyrimidine PNA·DNA-PNA hetero-triplex, to investigate the influence of linker flexibility on binding interactions of the E-base with thymine and uracil bases in geometry-optimised model systems. Hydrogen bond formation between the N2 E-base atom and target pyrimidine base 4-oxo groups in model systems containing a β-alanine linker (J Am Chem Soc 119:11116, 1997) was found to incur significant internal strain energy and the potential disruption of intra-stand aromatic base stacking interactions in an oligomeric context. In geometry-optimised model systems containing a 3-trans olefin linker (Bioorg Med Chem Lett 14:1551, 2004) the E-base swung out away from the target pyrimidine bases into the solvent. These findings are in qualitative agreement with calorimetric measurements in hybridisation experiments at T-A and U-A inversion sites. In contrast, calculations on a novel 2-cis olefin linker design indicate that it could permit simultaneous E-base hydrogen bonding with the thymine 4-oxo group, circumvention and solvent screening of the thymine 5-methyl group, and maintenance of triplex intra-stand base stacking interactions.
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Affiliation(s)
- Christopher M Topham
- Molecular Forces Consulting, 24 Avenue Jacques Besse, 81500, Lavaur, France.
- Computational Molecular Biophysics, IWR Der Universität Heidelberg, Im Neuenheimer Feld 368, 69120, Heidelberg, Germany.
- Center for Molecular Biophysics, University of Tennessee / Oak Ridge National Laboratory, P.O.Box 2008, Oak Ridge, TN, 37831-6309, USA.
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, TN, 37996, USA.
| | - Jeremy C Smith
- Computational Molecular Biophysics, IWR Der Universität Heidelberg, Im Neuenheimer Feld 368, 69120, Heidelberg, Germany
- Center for Molecular Biophysics, University of Tennessee / Oak Ridge National Laboratory, P.O.Box 2008, Oak Ridge, TN, 37831-6309, USA
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, TN, 37996, USA
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18
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Brodyagin N, Maryniak AL, Kumpina I, Talbott JM, Katkevics M, Rozners E, MacKay JA. Extended Peptide Nucleic Acid Nucleobases Based on Isoorotic Acid for the Recognition of A-U Base Pairs in Double-Stranded RNA. Chemistry 2021; 27:4332-4335. [PMID: 33439519 DOI: 10.1002/chem.202005401] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/12/2021] [Indexed: 02/06/2023]
Abstract
Peptide nucleic acids (PNA) with extended isoorotamide containing nucleobases (Io ) were designed for binding A-U base pairs in double-stranded RNA. Isothermal titration calorimetry and UV thermal melting experiments revealed improved affinity for A-U using the Io scaffold in PNA. PNAs having four sequential Io extended nucleobases maintained high binding affinity.
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Affiliation(s)
- Nikita Brodyagin
- Department of Chemistry, Binghamton University, Binghamton, New York, 13902, USA
| | - Aubrey L Maryniak
- Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, Pennsylvania, 17022, USA
| | - Ilze Kumpina
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia
| | - John M Talbott
- Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, Pennsylvania, 17022, USA
| | - Martins Katkevics
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga, LV-1006, Latvia
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, Binghamton, New York, 13902, USA
| | - James A MacKay
- Department of Chemistry and Biochemistry, Elizabethtown College, Elizabethtown, Pennsylvania, 17022, USA
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19
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Nucleobase-Modified Triplex-Forming Peptide Nucleic Acids for Sequence-Specific Recognition of Double-Stranded RNA. Methods Mol Biol 2021; 2105:157-172. [PMID: 32088869 DOI: 10.1007/978-1-0716-0243-0_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Because of the important roles noncoding RNAs play in gene expression, their sequence-specific recognition is important for both fundamental science and the pharmaceutical industry. However, most noncoding RNAs fold in complex helical structures that are challenging problems for molecular recognition. Herein, we describe a method for sequence-specific recognition of double-stranded RNA using peptide nucleic acids (PNAs) that form triple helices in the major grove of RNA under physiologically relevant conditions. We also outline methods for solid-phase conjugation of PNA with cell-penetrating peptides and fluorescent dyes. Protocols for PNA preparation and binding studies using isothermal titration calorimetry are described in detail.
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20
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Miao S, Liang Y, Rundell S, Bhunia D, Devari S, Munyaradzi O, Bong D. Unnatural bases for recognition of noncoding nucleic acid interfaces. Biopolymers 2021; 112:e23399. [PMID: 32969496 PMCID: PMC7855516 DOI: 10.1002/bip.23399] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/14/2020] [Accepted: 08/25/2020] [Indexed: 12/20/2022]
Abstract
The notion of using synthetic heterocycles instead of the native bases to interface with DNA and RNA has been explored for nearly 60 years. Unnatural bases compatible with the DNA/RNA coding interface have the potential to expand the genetic code and co-opt the machinery of biology to access new macromolecular function; accordingly, this body of research is core to synthetic biology. While much of the literature on artificial bases focuses on code expansion, there is a significant and growing effort on docking synthetic heterocycles to noncoding nucleic acid interfaces; this approach seeks to illuminate major processes of nucleic acids, including regulation of transcription, translation, transport, and transcript lifetimes. These major avenues of research at the coding and noncoding interfaces have in common fundamental principles in molecular recognition. Herein, we provide an overview of foundational literature in biophysics of base recognition and unnatural bases in coding to provide context for the developing area of targeting noncoding nucleic acid interfaces with synthetic bases, with a focus on systems developed through iterative design and biophysical study.
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Affiliation(s)
- Shiqin Miao
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Yufeng Liang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Sarah Rundell
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Debmalya Bhunia
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Shekar Devari
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Oliver Munyaradzi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Dennis Bong
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
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21
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Kumar V, Brodyagin N, Rozners E. Triplex-Forming Peptide Nucleic Acids with Extended Backbones. Chembiochem 2020; 21:3410-3416. [PMID: 32697857 PMCID: PMC7783598 DOI: 10.1002/cbic.202000432] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/20/2020] [Indexed: 01/15/2023]
Abstract
Peptide nucleic acid (PNA) forms a triple helix with double-stranded RNA (dsRNA) stabilized by a hydrogen-bonding zipper formed by PNA's backbone amides (N-H) interacting with RNA phosphate oxygens. This hydrogen-bonding pattern is enabled by the matching ∼5.7 Å spacing (typical for A-form dsRNA) between PNA's backbone amides and RNA phosphate oxygens. We hypothesized that extending the PNA's backbone by one -CH2 - group might bring the distance between PNA amide groups closer to 7 Å, which is favourable for hydrogen bonding to the B-form dsDNA phosphate oxygens. Extension of the PNA backbone was expected to selectively stabilize PNA-DNA triplexes compared to PNA-RNA. To test this hypothesis, we synthesized triplex-forming PNAs that had the pseudopeptide backbones extended by an additional -CH2 - group in three different positions. Isothermal titration calorimetry measurements of the binding affinity of these extended PNA analogues for the matched dsDNA and dsRNA showed that, contrary to our structural reasoning, extending the PNA backbone at any position had a strong negative effect on triplex stability. Our results suggest that PNAs might have an inherent preference for A-form-like conformations when binding double-stranded nucleic acids. It appears that the original six-atom-long PNA backbone is an almost perfect fit for binding to A-form nucleic acids.
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Affiliation(s)
- Vipin Kumar
- Department of Chemistry, Binghamton University Binghamton, New York, 13902, USA
| | - Nikita Brodyagin
- Department of Chemistry, Binghamton University Binghamton, New York, 13902, USA
| | - Eriks Rozners
- Department of Chemistry, Binghamton University Binghamton, New York, 13902, USA
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22
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Moccia M, Mercurio FA, Langella E, Piacenti V, Leone M, Adamo MFA, Saviano M. Structural Insights on Tiny Peptide Nucleic Acid (PNA) Analogues of miRNA-34a: An in silico and Experimental Integrated Approach. Front Chem 2020; 8:568575. [PMID: 33330358 PMCID: PMC7719796 DOI: 10.3389/fchem.2020.568575] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 11/02/2020] [Indexed: 11/17/2022] Open
Abstract
In the present work, structural features of the interaction between peptide nucleic acid (PNA)-based analogs of the tumor-suppressor microRNA-34a with both its binding sites on MYCN mRNA were investigated. In particular, the region from base 1 to 8 ("seed" region) of miR-34a was reproduced in the form of an 8-mer PNA fragment (tiny PNA), and binding to target 3'UTR MYCN mRNA, was studied by a seldom reported and detailed NMR characterization, providing evidence for the formation of anti-parallel duplexes with a well-organized structural core. The formation of PNA-3'UTR duplexes was also confirmed by Circular Dichroism, and their melting curves were measured by UV spectroscopy. Nevertheless, this study offered a valuable comparison between molecular dynamics predictions and experimental evidence, which showed great correlation. Preliminary uptake assays were carried out in Neuroblastoma Kelly cells, using short peptide conjugates as carriers and FITC fluorescent tag for subcellular localization. Moderate internalization was observed without the use of transfecting agents. The reported results corroborate the interest toward the design and development of chimeric PNA/RNA sequences as effective RNA-targeting agents.
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Affiliation(s)
- Maria Moccia
- Institute of Crystallography, National Research Council, Department of Chemical Sciences and Materials Technologies, Bari, Italy
| | - Flavia Anna Mercurio
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Emma Langella
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Valerio Piacenti
- Royal College of Surgeons in Ireland, Department of Pharmaceutical and Medicinal Chemistry, Dublin, Ireland
| | - Marilisa Leone
- Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy
| | - Mauro F. A. Adamo
- Royal College of Surgeons in Ireland, Department of Pharmaceutical and Medicinal Chemistry, Dublin, Ireland
| | - Michele Saviano
- Institute of Crystallography, National Research Council, Department of Chemical Sciences and Materials Technologies, Bari, Italy
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23
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Lee ETT, Sato Y, Nishizawa S. Small molecule-PNA oligomer conjugates for rRNA A-site at neutral pH for FID assays. Chem Commun (Camb) 2020; 56:14976-14979. [PMID: 33174546 DOI: 10.1039/d0cc06084d] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A triplex-forming PNA oligomer conjugated with a naphthyridine derivative (ATMND-C2-NH2) showed high selectivity and strong binding for the bacterial rRNA A-site at pH 7.0 (Kd = 190 ± 72 nM), which was accompanied by fluorogenic signaling that allowed the potential use of this conjugate probe in fluorescent indicator displacement assays.
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Affiliation(s)
- En Ting Tabitha Lee
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
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24
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Ryan C, Rozners E. Impact of Chirality and Position of Lysine Conjugation in Triplex-Forming Peptide Nucleic Acids. ACS OMEGA 2020; 5:28722-28729. [PMID: 33195925 PMCID: PMC7659144 DOI: 10.1021/acsomega.0c04021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
Conjugation with cationic lysine residues improves the biophysical and biological properties of peptide nucleic acids (PNAs). A single lysine is routinely used to improve the solubility and prevent aggregation of the neutral and hydrophobic amide backbone of PNA. Literature precedents include the attachment of lysine at either the N- or the C-terminus. Moreover, conjugation with short lysine peptides (four to eight residues) improves the cellular uptake of PNA akin to more complex cell-penetrating peptides. Herein, we report a systematic study of the effect of lysine location (N- vs C-terminus) and chirality (d- vs l-) on triple-helical binding of PNA to double-stranded RNA and DNA (dsRNA and dsDNA). The results confirmed our earlier findings that conjugation with lysine significantly increased the stability of PNA-dsRNA and PNA-dsDNA triplexes and that PNA affinity for dsRNA was about an order of magnitude higher than for the same sequence of dsDNA. In contrast, conjugation of PNA with noncharged amino acids decreased the affinity of PNA. Surprisingly, neither the location nor the chirality of lysine had significant impact on PNA affinity for either dsRNA or dsDNA. The results are consistent with the lack of chiral preorganization of single-stranded PNAs, even after conjugation with four d- or l-amino acids. Instead, the positive charge of lysine appears to be the main driving force behind the increased affinity.
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Affiliation(s)
- Christopher
A. Ryan
- Department of Chemistry, Binghamton University, The State University
of New York, Binghamton, New York 13902, United
States
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, The State University
of New York, Binghamton, New York 13902, United
States
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25
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Antibacterial Peptide Nucleic Acids-Facts and Perspectives. Molecules 2020; 25:molecules25030559. [PMID: 32012929 PMCID: PMC7038079 DOI: 10.3390/molecules25030559] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 12/13/2022] Open
Abstract
Antibiotic resistance is an escalating, worldwide problem. Due to excessive use of antibiotics, multidrug-resistant bacteria have become a serious threat and a major global healthcare problem of the 21st century. This fact creates an urgent need for new and effective antimicrobials. The common strategies for antibiotic discovery are based on either modifying existing antibiotics or screening compound libraries, but these strategies have not been successful in recent decades. An alternative approach could be to use gene-specific oligonucleotides, such as peptide nucleic acid (PNA) oligomers, that can specifically target any single pathogen. This approach broadens the range of potential targets to any gene with a known sequence in any bacterium, and could significantly reduce the time required to discover new antimicrobials or their redesign, if resistance arises. We review the potential of PNA as an antibacterial molecule. First, we describe the physicochemical properties of PNA and modifications of the PNA backbone and nucleobases. Second, we review the carriers used to transport PNA to bacterial cells. Furthermore, we discuss the PNA targets in antibacterial studies focusing on antisense PNA targeting bacterial mRNA and rRNA.
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26
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Kurosaki F, Chiba J, Oda Y, Hino A, Inouye M. 2-Aminopyridine as a Nucleobase Substitute for Adenine in DNA-like Architectures: Synthesis of Alkynyl C-Nucleotides and Their Hybridization Characteristics. J Org Chem 2020; 85:2666-2671. [PMID: 31875396 DOI: 10.1021/acs.joc.9b02750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Halogenated 2-aminopyridine was attached to the acetylene terminal of ethynyl C-2-deoxy-β-d-ribofuranoside as a nucleobase substitute, and then, the C-nucleoside was incorporated into natural DNAs. The resulting chimeric DNA constructed double helical structures with the complementary chimeric DNA. In the duplex, 2-aminopyridine functioned as an adenine analogue that formed a base pair with a non-natural thymine isostere. Artificial homooligomers were also prepared only from the adenine-type C-nucleoside and proven to form completely artificial double helices with the corresponding artificial thymine-type homooligomers.
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Affiliation(s)
- Fumihiro Kurosaki
- Graduate School of Pharmaceutical Sciences , University of Toyama , Toyama 930-0194 , Japan
| | - Junya Chiba
- Graduate School of Pharmaceutical Sciences , University of Toyama , Toyama 930-0194 , Japan
| | - Yutaro Oda
- Graduate School of Pharmaceutical Sciences , University of Toyama , Toyama 930-0194 , Japan
| | - Airi Hino
- Graduate School of Pharmaceutical Sciences , University of Toyama , Toyama 930-0194 , Japan
| | - Masahiko Inouye
- Graduate School of Pharmaceutical Sciences , University of Toyama , Toyama 930-0194 , Japan
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27
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Kumpina I, Brodyagin N, MacKay JA, Kennedy SD, Katkevics M, Rozners E. Synthesis and RNA-Binding Properties of Extended Nucleobases for Triplex-Forming Peptide Nucleic Acids. J Org Chem 2019; 84:13276-13298. [PMID: 31538780 DOI: 10.1021/acs.joc.9b01133] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Triple-helix formation, using Hoogsteen hydrogen bonding of triplex-forming oligonucleotides, represents an attractive method for sequence-specific recognition of double-stranded nucleic acids. However, practical applications using triple-helix-forming oligonucleotides and their analogues are limited to long homopurine sequences. The key problem for recognition of pyrimidines is that they present only one hydrogen-bond acceptor or donor group in the major groove. Herein, we report our first attempt to overcome this problem by using peptide nucleic acids (PNAs) modified with extended nucleobases that form three hydrogen bonds along the entire Hoogsteen edge of the Watson-Crick base pair. New nucleobase triples (five) were designed, and their hydrogen bonding feasibility was confirmed by ab initio calculations. PNA monomers carrying the modified nucleobases were synthesized and incorporated in short model PNA sequences. Isothermal titration calorimetry showed that these nucleobases had a modest binding affinity for their double-stranded RNA (dsRNA) targets. Finally, molecular modeling of the modified triples in PNA-dsRNA helix suggested that the modest binding affinity was caused by subtle structural deviations from ideal hydrogen-bonding arrangements or disrupted π-stacking of the extended nucleobase scaffolds.
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Affiliation(s)
- Ilze Kumpina
- Latvian Institute of Organic Synthesis , Aizkraukles 21 , Riga LV-1006 , Latvia
| | - Nikita Brodyagin
- Department of Chemistry , Binghamton University, State University of New York , Binghamton , New York 13902 , United States
| | - James A MacKay
- Department of Chemistry and Biochemistry , Elizabethtown College , Elizabethtown , Pennsylvania 17022 , United States
| | - Scott D Kennedy
- Department of Biochemistry and Biophysics , University of Rochester School of Medicine and Dentistry , Rochester , New York 14642 , United States
| | - Martins Katkevics
- Latvian Institute of Organic Synthesis , Aizkraukles 21 , Riga LV-1006 , Latvia
| | - Eriks Rozners
- Department of Chemistry , Binghamton University, State University of New York , Binghamton , New York 13902 , United States
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28
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Krishna MS, Wang Z, Zheng L, Bowry J, Ong AAL, Mu Y, Prabakaran M, Chen G. Incorporating G-C Pair-Recognizing Guanidinium into PNAs for Sequence and Structure Specific Recognition of dsRNAs over dsDNAs and ssRNAs. Biochemistry 2019; 58:3777-3788. [PMID: 31424191 DOI: 10.1021/acs.biochem.9b00608] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Recognition of RNAs under physiological conditions is important for the development of chemical probes and therapeutic ligands. Nucleobase-modified dsRNA-binding PNAs (dbPNAs) are promising for the recognition of dsRNAs in a sequence and structure specific manner under near-physiological conditions. Guanidinium is often present in proteins and small molecules for the recognition of G bases in nucleic acids, in cell-penetrating carriers, and in bioactive drug molecules, which might be due to the fact that guanidinium is amphiphilic and has unique hydrogen bonding and stacking properties. We hypothesized that a simple guanidinium moiety can be directly incorporated into PNAs to facilitate enhanced molecular recognition of G-C pairs in dsRNAs and improved bioactivity. We grafted a guanidinium moiety directly into a PNA monomer (designated as R) using a two-carbon linker as guided by computational modeling studies. The synthetic scheme of the PNA R monomer is relatively simple compared to that of the previously reported L monomer. We incorporated the R residue into various dbPNAs for binding studies. dbPNAs incorporated with R residues are excellent in sequence specifically recognizing G-C pairs in dsRNAs over dsDNA and ssRNAs. We demonstrated that the R residue is compatible with unmodified T and C and previously developed modified L and Q residues in dbPNAs for targeting model dsRNAs, the influenza A viral panhandle duplex structure, and the HIV-1 frameshift site RNA hairpin. Furthermore, R residues enhance the cellular uptake of PNAs.
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Affiliation(s)
- Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Zhenzhang Wang
- Temasek Life Science Laboratory, 1 Research Link, National University of Singapore , Singapore 117604
| | - Liangzhen Zheng
- School of Biological Sciences , Nanyang Technological University , Singapore 637551
| | - Jogesh Bowry
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371.,Department of Chemistry , University of Southampton , Southampton SO17 1BJ , U.K
| | - Alan Ann Lerk Ong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Yuguang Mu
- School of Biological Sciences , Nanyang Technological University , Singapore 637551
| | - Mookkan Prabakaran
- Temasek Life Science Laboratory, 1 Research Link, National University of Singapore , Singapore 117604
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
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29
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Ong AAL, Toh DFK, Krishna MS, Patil KM, Okamura K, Chen G. Incorporating 2-Thiouracil into Short Double-Stranded RNA-Binding Peptide Nucleic Acids for Enhanced Recognition of A-U Pairs and for Targeting a MicroRNA Hairpin Precursor. Biochemistry 2019; 58:3444-3453. [PMID: 31318532 DOI: 10.1021/acs.biochem.9b00521] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chemically modified short peptide nucleic acids (PNAs) recognize RNA duplexes under near physiological conditions by major-groove PNA·RNA-RNA triplex formation and show great promise for the development of RNA-targeting probes and therapeutics. Thymine (T) and uracil (U) are often incorporated into PNAs to recognize A-U pairs through major-groove T·A-U and U·A-U base triple formation. Incorporation of a modified nucleobase, 2-thiouracil (s2U), into triplex-forming oligonucleotides stabilizes both DNA and RNA triplexes. Thiolation of uracil causes a decrease in the dehydration energy penalty for triplex formation as well as a decrease in the pKa of the N3 atom, which may result in improved hydrogen bonding in addition to enhanced base stacking interactions, similar to the previously reported thiolation effect of pseudoisocytosine (J to L substitution). Here, we incorporated s2U into short PNAs, followed by binding studies of a series of s2U-modified PNAs. We demonstrated by nondenaturing polyacrylamide gel electrophoresis and thermal melting experiments that s2U and L incorporated into dsRNA-binding PNAs (dbPNAs) enhance the recognition of A-U and G-C pairs, respectively, in RNA duplexes in a position-independent manner, with no appreciable binding to the DNA duplex. Combining s2U and L modifications in dbPNAs facilitates enhanced recognition of dsRNAs and maintains selective binding to dsRNAs over ssRNAs. We further demonstrated through a cell-free assay the application of the s2U- and L-modified dbPNAs (8-mer, with a molecular mass of ∼2.3 kDa) in the inhibition of the pre-microRNA-198 maturation in a substrate-specific manner. Thus, s2U-modified dbPNAs may be generally useful for the enhanced and selective recognition of RNA duplexes and for the regulation of RNA functions.
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Affiliation(s)
- Alan Ann Lerk Ong
- NTU Institute for Health Technologies (HeathTech NTU), Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Drive , Singapore 637553.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Katsutomo Okamura
- Division of Biological Sciences , Nara Institute of Science and Technology , 8916-5 Takayama , Ikoma , Nara 630-0192 , Japan
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
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30
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Abstract
While <2% of DNA encodes for functional proteins, >70% is transcribed into RNA. Although the function of most RNA transcripts is unknown, such non-coding RNAs are attractive targets for molecular recognition because of the potentially important roles they play in regulation of gene expression and development of disease. In this chapter, we describe peptide nucleic acids (PNAs) that form sequence-specific triple helices with double-stranded RNA (dsRNA). We provide protocols for sequence design and biophysical characterization of PNAs and discuss first examples where such PNAs have been used for functional modulation of dsRNA. The triplex-forming PNAs represent a new approach for RNA recognition that may find future applications in fundamental science, biotechnology and medicine.
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