1
|
Brown A, Brill J, Amini R, Nurmi C, Li Y. Development of Better Aptamers: Structured Library Approaches, Selection Methods, and Chemical Modifications. Angew Chem Int Ed Engl 2024; 63:e202318665. [PMID: 38253971 DOI: 10.1002/anie.202318665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/22/2024] [Accepted: 01/22/2024] [Indexed: 01/24/2024]
Abstract
Systematic evolution of ligands by exponential enrichment (SELEX) has been used to discover thousands of aptamers since its development in 1990. Aptamers are short single-stranded oligonucleotides capable of binding to targets with high specificity and selectivity through structural recognition. While aptamers offer advantages over other molecular recognition elements such as their ease of production, smaller size, extended shelf-life, and lower immunogenicity, they have yet to show significant success in real-world applications. By analyzing the importance of structured library designs, reviewing different SELEX methodologies, and the effects of chemical modifications, we provide a comprehensive overview on the production of aptamers for applications in drug delivery systems, therapeutics, diagnostics, and molecular imaging.
Collapse
Affiliation(s)
- Alex Brown
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4 K1, Canada
| | - Jake Brill
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4 K1, Canada
| | - Ryan Amini
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4 K1, Canada
| | - Connor Nurmi
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4 K1, Canada
| | - Yingfu Li
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4 K1, Canada
| |
Collapse
|
2
|
Escamilla-Gutiérrez A, Córdova-Espinoza MG, Sánchez-Monciváis A, Tecuatzi-Cadena B, Regalado-García AG, Medina-Quero K. In silico selection of aptamers for bacterial toxins detection. J Biomol Struct Dyn 2023; 41:10909-10918. [PMID: 36546716 DOI: 10.1080/07391102.2022.2159529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 12/10/2022] [Indexed: 12/24/2022]
Abstract
The most commonly used toxins in biological warfare are staphylococcal enterotoxin B (3SEB), cholera toxin (1XTC), and botulinum toxin (3BTA). Uncovering novel strategies for identifying these toxins is paramount; therefore, aptamers are used for this purpose. Aptamers are single-stranded DNA or RNA oligonucleotides selected via Systematic Evolution of Ligands by Exponential Enrichment (SELEX) with high binding affinity and specificity against target molecules. However, SELEX in vitro is tedious; hence, adopting alternative in silico molecular docking approaches is necessary. We aimed to conduct molecular docking with accessible tools and obtain RNA aptamers. First, 4,820,095 sequences obtained from an initial library of 9.5 × 109 Python script sequences were used. The GraphClust program was used to create representative groups or clusters, and the DoGSiteScorer (https://proteins.plus/) was used to conduct binding site detection of the proteins: 5DO4 (thrombin), 3SEB, 1XTC, and 3BTA. rDock, HDock, and PatchDock were adopted, combining different docking program results (consensus scoring), to improve receptor-ligand prediction. An analysis of the poses and root mean square deviation (RMSD) was performed, and 468 structurally different aptamers were obtained. The DoGSiteScorer program predicted the binding site of each protein to direct the interaction with the aptamer. Candidate aptamers for 3SEB, 1XTC, and 3BTA were selected according to the pose value considering the closeness of the interaction with a lower mean of 45.923 Å, 45.854 Å, and 72.490 Å, respectively.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Alejandro Escamilla-Gutiérrez
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México
- Hospital General, Instituto Mexicano del Seguro Social IMSS, Ciudad de México, México
| | - María Guadalupe Córdova-Espinoza
- Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México
- Laboratorio de Inmunología, Escuela Militar de Graduados de Sanidad, Secretaría de la Defensa Nacional, Ciudad de México, México
| | - Anahí Sánchez-Monciváis
- Laboratorio de Inmunología, Escuela Militar de Graduados de Sanidad, Secretaría de la Defensa Nacional, Ciudad de México, México
| | - Brenda Tecuatzi-Cadena
- Laboratorio de Inmunología, Escuela Militar de Graduados de Sanidad, Secretaría de la Defensa Nacional, Ciudad de México, México
| | - Ana Gabriela Regalado-García
- Laboratorio de Inmunología, Escuela Militar de Graduados de Sanidad, Secretaría de la Defensa Nacional, Ciudad de México, México
| | - Karen Medina-Quero
- Laboratorio de Inmunología, Escuela Militar de Graduados de Sanidad, Secretaría de la Defensa Nacional, Ciudad de México, México
| |
Collapse
|
3
|
Yang LF, Ling M, Kacherovsky N, Pun SH. Aptamers 101: aptamer discovery and in vitro applications in biosensors and separations. Chem Sci 2023; 14:4961-4978. [PMID: 37206388 PMCID: PMC10189874 DOI: 10.1039/d3sc00439b] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 04/14/2023] [Indexed: 05/21/2023] Open
Abstract
Aptamers are single-stranded nucleic acids that bind and recognize targets much like antibodies. Recently, aptamers have garnered increased interest due to their unique properties, including inexpensive production, simple chemical modification, and long-term stability. At the same time, aptamers possess similar binding affinity and specificity as their protein counterpart. In this review, we discuss the aptamer discovery process as well as aptamer applications to biosensors and separations. In the discovery section, we describe the major steps of the library selection process for aptamers, called systematic evolution of ligands by exponential enrichment (SELEX). We highlight common approaches and emerging strategies in SELEX, from starting library selection to aptamer-target binding characterization. In the applications section, we first evaluate recently developed aptamer biosensors for SARS-CoV-2 virus detection, including electrochemical aptamer-based sensors and lateral flow assays. Then we discuss aptamer-based separations for partitioning different molecules or cell types, especially for purifying T cell subsets for therapeutic applications. Overall, aptamers are promising biomolecular tools and the aptamer field is primed for expansion in biosensing and cell separation.
Collapse
Affiliation(s)
- Lucy F Yang
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington Seattle Washington USA
| | - Melissa Ling
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington Seattle Washington USA
| | - Nataly Kacherovsky
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington Seattle Washington USA
| | - Suzie H Pun
- Department of Bioengineering and Molecular Engineering and Sciences Institute, University of Washington Seattle Washington USA
| |
Collapse
|
4
|
Liu X, Hu J, Ning Y, Xu H, Cai H, Yang A, Shi Z, Li Z. Aptamer Technology and Its Applications in Bone Diseases. Cell Transplant 2023; 32:9636897221144949. [PMID: 36591965 PMCID: PMC9811309 DOI: 10.1177/09636897221144949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Aptamers are single-stranded nucleic acids (DNA, short RNA, or other artificial molecules) produced by the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) technology, which can be tightly and specifically combined with desired targets. As a comparable alternative to antibodies, aptamers have many advantages over traditional antibodies such as a strong chemical stability and rapid bulk production. In addition, aptamers can bind targets in various ways, and are not limited like the antigen-antibody combination. Studies have shown that aptamers have tremendous potential to diagnose and treat clinical diseases. However, only a few aptamer-based drugs have been used because of limitations of the aptamers and SELEX technology. To promote the development and applications of aptamers, we present a review of the methods optimizing the SELEX technology and modifying aptamers to boost the selection success rate and improve aptamer characteristics. In addition, we review the application of aptamers to treat bone diseases.
Collapse
Affiliation(s)
- Xiangzhong Liu
- Department of Orthopaedics, Wuhan Third
Hospital, Tongren Hospital of Wuhan University, Wuhan, China
| | - Jing Hu
- Wuhan Children’s Hospital, Tongji
Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Yu Ning
- Department of Orthopaedics, Xiangyang
Hospital of Traditional Chinese Medicine Affiliated to Hubei University of Chinese
Medicine, Xiangyang, China
| | - Haijia Xu
- Department of Orthopaedics, Wuhan Third
Hospital, Tongren Hospital of Wuhan University, Wuhan, China
| | - Hantao Cai
- Department of Orthopaedics, Wenling
First People’s Hospital, Taizhou, China
| | - Aofei Yang
- Department of Orthopaedics, Hubei
Hospital of Traditional Chinese Medicine, Wuhan, China
| | - Zhengshuai Shi
- Department of Orthopaedics, Wuhan
Sports University, Wuhan, China
| | - Zhanghua Li
- Department of Orthopaedics, Wuhan Third
Hospital, Tongren Hospital of Wuhan University, Wuhan, China,Zhanghua Li, Department of Orthopaedics,
Wuhan Third Hospital, Tongren Hospital of Wuhan University, No. 216, Guanshan
Avenue, Hongshan District, Wuhan 430074, Hubei Province, China.
| |
Collapse
|
5
|
Jerome CA, Hoshika S, Bradley KM, Benner SA, Biondi E. In vitro evolution of ribonucleases from expanded genetic alphabets. Proc Natl Acad Sci U S A 2022; 119. [PMID: 36279447 PMCID: PMC9636917 DOI: 10.1073/pnas.2208261119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability of nucleic acids to catalyze reactions (as well as store and transmit information) is important for both basic and applied science, the first in the context of molecular evolution and the origin of life and the second for biomedical applications. However, the catalytic power of standard nucleic acids (NAs) assembled from just four nucleotide building blocks is limited when compared with that of proteins. Here, we assess the evolutionary potential of libraries of nucleic acids with six nucleotide building blocks as reservoirs for catalysis. We compare the outcomes of in vitro selection experiments toward RNA-cleavage activity of two nucleic acid libraries: one built from the standard four independently replicable nucleotides and the other from six, with the two added nucleotides coming from an artificially expanded genetic information system (AEGIS). Results from comparative experiments suggest that DNA libraries with increased chemical diversity, higher information density, and larger searchable sequence spaces are one order of magnitude richer reservoirs of molecules that catalyze the cleavage of a phosphodiester bond in RNA than DNA libraries built from a standard four-nucleotide alphabet. Evolved AEGISzymes with nitro-carrying nucleobase Z appear to exploit a general acid–base catalytic mechanism to cleave that bond, analogous to the mechanism of the ribonuclease A family of protein enzymes and heavily modified DNAzymes. The AEGISzyme described here represents a new type of catalysts evolved from libraries built from expanded genetic alphabets.
Collapse
|
6
|
Wu Y, Zhu L, Li S, Chu H, Wang X, Xu W. High content design of riboswitch biosensors: All-around rational module-by-module design. Biosens Bioelectron 2022; 220:114887. [DOI: 10.1016/j.bios.2022.114887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/27/2022] [Accepted: 11/03/2022] [Indexed: 11/11/2022]
|
7
|
Kohlberger M, Gadermaier G. SELEX: Critical factors and optimization strategies for successful aptamer selection. Biotechnol Appl Biochem 2022; 69:1771-1792. [PMID: 34427974 PMCID: PMC9788027 DOI: 10.1002/bab.2244] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 08/22/2021] [Indexed: 12/30/2022]
Abstract
Within the last decade, the application range of aptamers in biochemistry and medicine has expanded rapidly. More than just a replacement for antibodies, these intrinsically structured RNA- or DNA-oligonucleotides show great potential for utilization in diagnostics, specific drug delivery, and treatment of certain medical conditions. However, what is analyzed less frequently is the process of aptamer identification known as systematic evolution of ligands by exponential enrichment (SELEX) and the functional mechanisms that lie at its core. SELEX involves numerous singular processes, each of which contributes to the success or failure of aptamer generation. In this review, critical steps during aptamer selection are discussed in-depth, and specific problems are presented along with potential solutions. The discussed aspects include the size and molecule type of the selected target, the nature and stringency of the selection process, the amplification step with its possible PCR bias, the efficient regeneration of RNA or single-stranded DNA, and the different sequencing procedures and screening assays currently available. Finally, useful quality control steps and their role within SELEX are presented. By understanding the mechanisms through which aptamer selection is influenced, the design of more efficient SELEX procedures leading to a higher success rate in aptamer identification is enabled.
Collapse
Affiliation(s)
- Michael Kohlberger
- Department of BiosciencesParis Lodron University SalzburgSalzburgAustria,Christian Doppler Laboratory for Biosimilar CharacterizationParis Lodron University SalzburgSalzburgAustria
| | - Gabriele Gadermaier
- Department of BiosciencesParis Lodron University SalzburgSalzburgAustria,Christian Doppler Laboratory for Biosimilar CharacterizationParis Lodron University SalzburgSalzburgAustria
| |
Collapse
|
8
|
Liu F, Zhang C, Duan Y, Ma J, Wang Y, Chen G. In vitro selection and characterization of a DNA aptamer targeted to Prorocentrum minimum-A common harmful algae. Sci Total Environ 2022; 830:154771. [PMID: 35339548 DOI: 10.1016/j.scitotenv.2022.154771] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/08/2022] [Accepted: 03/19/2022] [Indexed: 06/14/2023]
Abstract
Prorocentrum minimum is a common diarrhetic shellfish toxins-producing marine microalga that may seriously endanger marine resources and cause great economic losses. The development of a novel rapid detection technique is of great importance for the prevention and control of the damage caused by P. minimum. In this study, the aptamer against P. minimum was for the first time generated from an artificially synthesized single-stranded DNA library by systematic evolution of ligand by exponential enrichment (SELEX), using P. minimum and P. minimum-related species, including Prorocentrum donghaiense, Prorocentrum lima and Prorocentrum micans as target and counter-screening species, respectively. The aptamer library was successfully obtained at the end of 18 rounds of SELEX-screening by continuously monitoring the binding ratio of the resultant ssDNA from each round. Three sequences (Apt 1, Apt 2 and Apt 3) with the highest frequency in the aptamer library resulted from high-throughput sequencing were first selected as candidate aptamers. The secondary structure of these sequences was predicted and analyzed. In addition, the specificity and affinity of these candidate aptamers were determined by flow cytometry analysis. The results indicated that these aptamers had high specificity and affinity, with a KD of (224.6 ± 8.8) nM (Apt 1), (286.6 ± 13.9) nM (Apt 2) and (388.5 ± 44.6) nM (Apt 3), respectively. Apt 1 was therefore chosen as the best aptamer against P. minimum. Finally, the fluorescence microscopic examination further confirmed that Apt 1 can well bind to P. minimum. In summary, Apt 1 may be promising for being used as a novel molecular recognition element for P. minimum.
Collapse
Affiliation(s)
- Fuguo Liu
- School of Marine Science and Technology, Harbin Institute of Technology (Weihai), Weihai 264209, PR China; School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Chunyun Zhang
- School of Marine Science and Technology, Harbin Institute of Technology (Weihai), Weihai 264209, PR China; School of Marine Sciences, Ningbo University, Ningbo 315211, PR China
| | - Yu Duan
- School of Marine Science and Technology, Harbin Institute of Technology (Weihai), Weihai 264209, PR China
| | - Jinju Ma
- School of Marine Science and Technology, Harbin Institute of Technology (Weihai), Weihai 264209, PR China
| | - Yuanyuan Wang
- School of Marine Science and Technology, Harbin Institute of Technology (Weihai), Weihai 264209, PR China
| | - Guofu Chen
- School of Marine Science and Technology, Harbin Institute of Technology (Weihai), Weihai 264209, PR China.
| |
Collapse
|
9
|
Qi S, Duan N, Khan IM, Dong X, Zhang Y, Wu S, Wang Z. Strategies to manipulate the performance of aptamers in SELEX, post-SELEX and microenvironment. Biotechnol Adv 2022; 55:107902. [DOI: 10.1016/j.biotechadv.2021.107902] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/21/2021] [Accepted: 12/30/2021] [Indexed: 02/07/2023]
|
10
|
Yu H, Alkhamis O, Canoura J, Liu Y, Xiao Y. Advances and Challenges in Small‐Molecule DNA Aptamer Isolation, Characterization, and Sensor Development. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202008663] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Haixiang Yu
- Department of Chemistry and Biochemistry Florida International University 11200 SW 8th Street Miami FL 33199 USA
| | - Obtin Alkhamis
- Department of Chemistry and Biochemistry Florida International University 11200 SW 8th Street Miami FL 33199 USA
| | - Juan Canoura
- Department of Chemistry and Biochemistry Florida International University 11200 SW 8th Street Miami FL 33199 USA
| | - Yingzhu Liu
- Department of Chemistry and Biochemistry Florida International University 11200 SW 8th Street Miami FL 33199 USA
| | - Yi Xiao
- Department of Chemistry and Biochemistry Florida International University 11200 SW 8th Street Miami FL 33199 USA
| |
Collapse
|
11
|
Yu H, Alkhamis O, Canoura J, Liu Y, Xiao Y. Advances and Challenges in Small-Molecule DNA Aptamer Isolation, Characterization, and Sensor Development. Angew Chem Int Ed Engl 2021; 60:16800-16823. [PMID: 33559947 PMCID: PMC8292151 DOI: 10.1002/anie.202008663] [Citation(s) in RCA: 144] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 11/16/2021] [Indexed: 12/12/2022]
Abstract
Aptamers are short oligonucleotides isolated in vitro from randomized libraries that can bind to specific molecules with high affinity, and offer a number of advantages relative to antibodies as biorecognition elements in biosensors. However, it remains difficult and labor-intensive to develop aptamer-based sensors for small-molecule detection. Here, we review the challenges and advances in the isolation and characterization of small-molecule-binding DNA aptamers and their use in sensors. First, we discuss in vitro methodologies for the isolation of aptamers, and provide guidance on selecting the appropriate strategy for generating aptamers with optimal binding properties for a given application. We next examine techniques for characterizing aptamer-target binding and structure. Afterwards, we discuss various small-molecule sensing platforms based on original or engineered aptamers, and their detection applications. Finally, we conclude with a general workflow to develop aptamer-based small-molecule sensors for real-world applications.
Collapse
Affiliation(s)
- Haixiang Yu
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA
| | - Obtin Alkhamis
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA
| | - Juan Canoura
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA
| | - Yingzhu Liu
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA
| | - Yi Xiao
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA
| |
Collapse
|
12
|
Bashir A, Yang Q, Wang J, Hoyer S, Chou W, McLean C, Davis G, Gong Q, Armstrong Z, Jang J, Kang H, Pawlosky A, Scott A, Dahl GE, Berndl M, Dimon M, Ferguson BS. Machine learning guided aptamer refinement and discovery. Nat Commun 2021; 12:2366. [PMID: 33888692 PMCID: PMC8062585 DOI: 10.1038/s41467-021-22555-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/18/2021] [Indexed: 02/07/2023] Open
Abstract
Aptamers are single-stranded nucleic acid ligands that bind to target molecules with high affinity and specificity. They are typically discovered by searching large libraries for sequences with desirable binding properties. These libraries, however, are practically constrained to a fraction of the theoretical sequence space. Machine learning provides an opportunity to intelligently navigate this space to identify high-performing aptamers. Here, we propose an approach that employs particle display (PD) to partition a library of aptamers by affinity, and uses such data to train machine learning models to predict affinity in silico. Our model predicted high-affinity DNA aptamers from experimental candidates at a rate 11-fold higher than random perturbation and generated novel, high-affinity aptamers at a greater rate than observed by PD alone. Our approach also facilitated the design of truncated aptamers 70% shorter and with higher binding affinity (1.5 nM) than the best experimental candidate. This work demonstrates how combining machine learning and physical approaches can be used to expedite the discovery of better diagnostic and therapeutic agents. Current aptamer discovery approaches are unable to probe the complete space of possible sequences. Here, the authors use machine learning to facilitate the development of DNA aptamers with improved binding affinities, and truncate them without significantly compromising binding affinity.
Collapse
Affiliation(s)
| | - Qin Yang
- Aptitude Medical Systems Inc., Santa Barbara, CA, USA
| | - Jinpeng Wang
- Aptitude Medical Systems Inc., Santa Barbara, CA, USA
| | | | - Wenchuan Chou
- Aptitude Medical Systems Inc., Santa Barbara, CA, USA
| | | | | | - Qiang Gong
- Aptitude Medical Systems Inc., Santa Barbara, CA, USA
| | | | - Junghoon Jang
- Aptitude Medical Systems Inc., Santa Barbara, CA, USA
| | - Hui Kang
- Aptitude Medical Systems Inc., Santa Barbara, CA, USA
| | | | | | | | | | | | | |
Collapse
|
13
|
Dagenais P, Legault P. In Vitro Selection of Varkud Satellite Ribozyme Variants that Cleave a Modified Stem-Loop Substrate. Methods Mol Biol 2021; 2167:61-77. [PMID: 32712915 DOI: 10.1007/978-1-0716-0716-9_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In vitro selection is an established approach to create artificial ribozymes with defined activities or to modify the properties of naturally occurring ribozymes. For the Varkud satellite ribozyme of Neurospora, an in vitro selection protocol based on its phosphodiester bond cleavage activity has not been previously reported. Here, we describe a simple protocol for cleavage-based in vitro selection that we recently used to identify variants of the Varkud satellite ribozyme able to target and cleave a non-natural stem-loop substrate derived from the HIV-1 TAR RNA. It allows quick selection of active ribozyme variants from the transcription reaction based on the size of the self-cleavage product without the need for RNA labeling. This results in a streamlined procedure that is easily adaptable to engineer ribozymes with new activities.
Collapse
Affiliation(s)
- Pierre Dagenais
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montreal, QC, Canada
| | - Pascale Legault
- Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montreal, QC, Canada.
| |
Collapse
|
14
|
Zhong Y, Zhao J, Li J, Liao X, Chen F. Advances of aptamers screened by Cell-SELEX in selection procedure, cancer diagnostics and therapeutics. Anal Biochem 2020; 598:113620. [PMID: 32087127 DOI: 10.1016/j.ab.2020.113620] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 02/10/2020] [Accepted: 02/10/2020] [Indexed: 12/23/2022]
Abstract
Aptamers are a class of short artificial single-stranded oligo(deoxy) nucleotides that can bind to different targets, which generated by Systematic Evolution of Ligands by Exponential Enrichment (SELEX). Due to excellent selectivity and high affinity to targets, aptamers hold considerable potential as molecular probe in diverse applications ranging from ensuring food safety, monitoring environment, disease diagnosis to therapy. This review highlights recent development and challenges about aptamers screened by Cell-SELEX, and its application about cancer diagnostics and therapeutics. Advances about some operation methods such as seperation method and culture method in aptamers selection procedure were summarized in this paper. Some common challenges and technological difficulties such as nonspecific binding and biostability were discussed. Up to now, the recent endeavors about cancer diagnostic and therapeutic applications of aptamers are summarized and expatiated. Most of aptamers screened by Cell-SELEX took tumor cells as target cells, and such aptamers have been assembled to various aptasensor for cancer diagnosis. Aptamers conjugated various drugs or nanomaterials are functioned for cancer target therapy to improve drugs delivery efficiency and reduce side effects. Furthermore, the duplexed aptamer is discussed to be applied for cancer cells detection and some conflicts of theories about duplexed aptamer designs are analyzed.
Collapse
Affiliation(s)
- Yi Zhong
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, China; National Center for International Research of Bio-targeting Theranostics, Guangxi Key Laboratory of Bio-targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Jiayao Zhao
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical University, Nanning, China; National Center for International Research of Bio-targeting Theranostics, Guangxi Key Laboratory of Bio-targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning, 530021, Guangxi, China
| | - Jiazhao Li
- Qionglai maternal&Child health care hospital, Chengdu, 611530, Sichuan, China
| | - Xin Liao
- School of laboratory medical and Life science, Wenzhou Medical University, Wenzhou, 325000, Fujian, China
| | - Fengling Chen
- National Center for International Research of Bio-targeting Theranostics, Guangxi Key Laboratory of Bio-targeting Theranostics, Collaborative Innovation Center for Targeting Tumor Diagnosis and Therapy, Guangxi Medical University, Nanning, 530021, Guangxi, China.
| |
Collapse
|
15
|
Chizzolini F, Passalacqua LFM, Oumais M, Dingilian AI, Szostak JW, Lupták A. Large Phenotypic Enhancement of Structured Random RNA Pools. J Am Chem Soc 2020; 142:1941-1951. [PMID: 31887027 DOI: 10.1021/jacs.9b11396] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Laboratory evolution of functional RNAs has applications in many areas of chemical and synthetic biology. In vitro selections critically depend on the presence of functional molecules, such as aptamers and ribozymes, in the starting sequence pools. For selection of novel functions the pools are typically transcribed from random-sequence DNA templates, yielding a highly diverse set of RNAs that contain a multitude of folds and biochemical activities. The phenotypic potential, the frequency of functional RNAs, is very low, requiring large complexity of starting pools, surpassing 1015 different sequences, to identify highly active isolates. Furthermore, the majority of random sequences is not structured and has a high propensity for aggregation; the in vitro selection process thus involves not just enrichment of functional RNAs, but also their purification from aggregation-prone "free-riders". We reasoned that purification of the nonaggregating, monomeric subpopulation of a random-sequence RNA pool will yield pools of folded, functional RNAs. We performed six rounds of selection for monomeric sequences and show that the enriched population is compactly folded. In vitro selections originating from various mixtures of the compact pool and a fully random pool showed that sequences from the compact pool always dominate the population once a biochemical activity is detectable. A head-to-head competition of the two pools starting from a low (5 × 1012) sequence diversity revealed that the phenotypic potential of the compact pool is about 1000-times higher than the fully random pool. A selection for folded and monomeric RNA pools thus greatly increases the frequency of functional RNAs from that seen in random-sequence pools, providing a facile experimental approach to isolation of highly active functional RNAs from low-diversity populations.
Collapse
Affiliation(s)
- Fabio Chizzolini
- Department of Pharmaceutical Sciences , University of California at Irvine , Irvine , California 92697 , United States
| | - Luiz F M Passalacqua
- Department of Pharmaceutical Sciences , University of California at Irvine , Irvine , California 92697 , United States
| | - Mona Oumais
- Department of Chemistry , University of California at Irvine , Irvine , California 92697 , United States
| | - Armine I Dingilian
- Department of Pharmaceutical Sciences , University of California at Irvine , Irvine , California 92697 , United States
| | - Jack W Szostak
- Howard Hughes Medical Institute, Department of Molecular Biology, and Center for Computational and Integrative Biology , Massachusetts General Hospital , Boston , Massachusetts 02114 , United States.,Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Andrej Lupták
- Department of Pharmaceutical Sciences , University of California at Irvine , Irvine , California 92697 , United States.,Department of Chemistry , University of California at Irvine , Irvine , California 92697 , United States.,Department of Molecular Biology and Biochemistry , University of California at Irvine , Irvine , California 92697 , United States
| |
Collapse
|
16
|
Wang T, Chen C, Larcher LM, Barrero RA, Veedu RN. Three decades of nucleic acid aptamer technologies: Lessons learned, progress and opportunities on aptamer development. Biotechnol Adv 2018; 37:28-50. [PMID: 30408510 DOI: 10.1016/j.biotechadv.2018.11.001] [Citation(s) in RCA: 263] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/28/2018] [Accepted: 11/04/2018] [Indexed: 02/07/2023]
Abstract
Aptamers are short single-stranded nucleic acid sequences capable of binding to target molecules in a way similar to antibodies. Due to various advantages such as prolonged shelf life, low batch to batch variation, low/no immunogenicity, freedom to incorporate chemical modification for enhanced stability and targeting capacity, aptamers quickly found their potential in diverse applications ranging from therapy, drug delivery, diagnosis, and functional genomics to bio-sensing. Aptamers are generated by a process called SELEX. However, the current overall success rate of SELEX is far from being satisfactory, and still presents a major obstacle for aptamer-based research and application. The need for an efficient selection strategy consisting of defined procedures to deal with a wide variety of targets is significantly important. In this work, by analyzing key aspects of SELEX including initial library design, target preparation, PCR optimization, and single strand DNA separation, we provide a comprehensive analysis of individual steps to facilitate researchers intending to develop personalized protocols to address many of the obstacles in SELEX. In addition, this review provides suggestions and opinions for future aptamer development procedures to address the concerns on key SELEX steps, and post-SELEX modifications.
Collapse
Affiliation(s)
- Tao Wang
- Centre for Comparative Genomics, Murdoch University, Perth 6150, Australia; Perron Institute for Neurological and Translational Science, Perth 6009, Australia; School of Nursing, Zhengzhou University & Nursing Department, The First Affiliated Hospital of Zheng Zhou University, Zhengzhou 450001, China
| | - Changying Chen
- School of Nursing, Zhengzhou University & Nursing Department, The First Affiliated Hospital of Zheng Zhou University, Zhengzhou 450001, China
| | - Leon M Larcher
- Centre for Comparative Genomics, Murdoch University, Perth 6150, Australia
| | - Roberto A Barrero
- Centre for Comparative Genomics, Murdoch University, Perth 6150, Australia
| | - Rakesh N Veedu
- Centre for Comparative Genomics, Murdoch University, Perth 6150, Australia; Perron Institute for Neurological and Translational Science, Perth 6009, Australia.
| |
Collapse
|
17
|
Nakatsuka N, Yang KA, Abendroth JM, Cheung KM, Xu X, Yang H, Zhao C, Zhu B, Rim YS, Yang Y, Weiss PS, Stojanović MN, Andrews AM. Aptamer-field-effect transistors overcome Debye length limitations for small-molecule sensing. Science 2018; 362:319-324. [PMID: 30190311 DOI: 10.1126/science.aao6750] [Citation(s) in RCA: 413] [Impact Index Per Article: 68.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 04/30/2018] [Accepted: 08/06/2018] [Indexed: 12/17/2022]
Abstract
Detection of analytes by means of field-effect transistors bearing ligand-specific receptors is fundamentally limited by the shielding created by the electrical double layer (the "Debye length" limitation). We detected small molecules under physiological high-ionic strength conditions by modifying printed ultrathin metal-oxide field-effect transistor arrays with deoxyribonucleotide aptamers selected to bind their targets adaptively. Target-induced conformational changes of negatively charged aptamer phosphodiester backbones in close proximity to semiconductor channels gated conductance in physiological buffers, resulting in highly sensitive detection. Sensing of charged and electroneutral targets (serotonin, dopamine, glucose, and sphingosine-1-phosphate) was enabled by specifically isolated aptameric stem-loop receptors.
Collapse
Affiliation(s)
- Nako Nakatsuka
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Kyung-Ae Yang
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University, New York, NY 10032, USA
| | - John M Abendroth
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Kevin M Cheung
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Xiaobin Xu
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Hongyan Yang
- Department of Psychiatry and Biobehavioral Science, Semel Institute for Neuroscience and Human Behavior, and Hatos Center for Neuropharmacology, University of California, Los Angeles, CA 90095, USA
| | - Chuanzhen Zhao
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Bowen Zhu
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.,Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA
| | - You Seung Rim
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.,Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA
| | - Yang Yang
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.,Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA
| | - Paul S Weiss
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA. .,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.,Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA
| | - Milan N Stojanović
- Center for Innovative Diagnostic and Therapeutic Approaches, Department of Medicine, Columbia University, New York, NY 10032, USA. .,Departments of Biomedical Engineering and Systems Biology, Columbia University, New York, NY 10032, USA
| | - Anne M Andrews
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA. .,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.,Department of Psychiatry and Biobehavioral Science, Semel Institute for Neuroscience and Human Behavior, and Hatos Center for Neuropharmacology, University of California, Los Angeles, CA 90095, USA
| |
Collapse
|
18
|
Vorobyeva MA, Davydova AS, Vorobjev PE, Pyshnyi DV, Venyaminova AG. Key Aspects of Nucleic Acid Library Design for in Vitro Selection. Int J Mol Sci 2018; 19:E470. [PMID: 29401748 PMCID: PMC5855692 DOI: 10.3390/ijms19020470] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 02/07/2023] Open
Abstract
Nucleic acid aptamers capable of selectively recognizing their target molecules have nowadays been established as powerful and tunable tools for biospecific applications, be it therapeutics, drug delivery systems or biosensors. It is now generally acknowledged that in vitro selection enables one to generate aptamers to almost any target of interest. However, the success of selection and the affinity of the resulting aptamers depend to a large extent on the nature and design of an initial random nucleic acid library. In this review, we summarize and discuss the most important features of the design of nucleic acid libraries for in vitro selection such as the nature of the library (DNA, RNA or modified nucleotides), the length of a randomized region and the presence of fixed sequences. We also compare and contrast different randomization strategies and consider computer methods of library design and some other aspects.
Collapse
Affiliation(s)
- Maria A. Vorobyeva
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
| | - Anna S. Davydova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
| | - Pavel E. Vorobjev
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
- Department of Natural Sciences, Novosibirsk State University, Pirogova St., 2, 630090 Novosibirsk, Russia
| | - Dmitrii V. Pyshnyi
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
- Department of Natural Sciences, Novosibirsk State University, Pirogova St., 2, 630090 Novosibirsk, Russia
| | - Alya G. Venyaminova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentiev Ave., 8, 630090 Novosibirsk, Russia; (A.S.D.); (P.E.V.); (D.V.P.); (A.G.V.)
| |
Collapse
|
19
|
|
20
|
Abdelsayed MM, Ho BT, Vu MMK, Polanco J, Spitale RC, Lupták A. Multiplex Aptamer Discovery through Apta-Seq and Its Application to ATP Aptamers Derived from Human-Genomic SELEX. ACS Chem Biol 2017; 12:2149-2156. [PMID: 28661647 DOI: 10.1021/acschembio.7b00001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Laboratory-evolved RNAs bind a wide variety of targets and serve highly diverse functions, including as diagnostic and therapeutic aptamers. The majority of aptamers have been identified using in vitro selection (SELEX), a molecular evolution technique based on selecting target-binding RNAs from highly diverse pools through serial rounds of enrichment and amplification. In vitro selection typically yields multiple distinct motifs of highly variable abundance and target-binding affinities. The discovery of new aptamers is often limited by the difficulty of characterizing the selected motifs, because testing of individual sequences tends to be a tedious process. To facilitate the discovery of new aptamers within in vitro selected pools, we developed Apta-Seq, a multiplex analysis based on quantitative, ligand-dependent 2' acylation of solvent-accessible regions of the selected RNA pools, followed by reverse transcription (SHAPE) and deep sequencing. The method reveals, in a single sequencing experiment, the identity, structural features, and target dissociation constants for aptamers present in the selected pool. Application of Apta-Seq to a human genomic pool enriched for ATP-binding RNAs yielded three new aptamers, which together with previously identified human aptamers suggest that ligand-binding RNAs may be common in mammals.
Collapse
Affiliation(s)
- Michael M. Abdelsayed
- Department
of Molecular Biology and Biochemistry, University of California—Irvine, Irvine, California 92697, United States
| | - Bao T. Ho
- Department
of Pharmaceutical Sciences, University of California—Irvine, Irvine, California 92697, United States
| | - Michael M. K. Vu
- Department
of Chemistry, University of California—Irvine, Irvine, California 92697, United States
| | - Julio Polanco
- Department
of Molecular Biology and Biochemistry, University of California—Irvine, Irvine, California 92697, United States
| | - Robert C. Spitale
- Department
of Pharmaceutical Sciences, University of California—Irvine, Irvine, California 92697, United States
- Department
of Chemistry, University of California—Irvine, Irvine, California 92697, United States
| | - Andrej Lupták
- Department
of Molecular Biology and Biochemistry, University of California—Irvine, Irvine, California 92697, United States
- Department
of Pharmaceutical Sciences, University of California—Irvine, Irvine, California 92697, United States
- Department
of Chemistry, University of California—Irvine, Irvine, California 92697, United States
| |
Collapse
|
21
|
Sharma TK, Bruno JG, Dhiman A. ABCs of DNA aptamer and related assay development. Biotechnol Adv 2017; 35:275-301. [PMID: 28108354 DOI: 10.1016/j.biotechadv.2017.01.003] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 11/19/2016] [Accepted: 01/17/2017] [Indexed: 12/14/2022]
Abstract
This review is intended to guide the novice in aptamer research and development to understand virtually all of the aptamer development options and currently available assay modalities. Aptamer development topics range from discussions of basic and advanced versions of Systematic Evolution of Ligands by EXponential Enrichment (SELEX) and SELEX variations involving incorporation of exotic unnatural nucleotides to expand library diversity for even greater aptamer affinity and specificity to improved next generation methods of DNA sequencing, screening and tracking aptamer development throughout the SELEX process and characterization of lead aptamer candidates. Aptamer assay development topics include descriptions of various colorimetric and fluorescent assays in microplates or on membranes including homogeneous beacon and multiplexed Fluorescence Resonance Energy Transfer (FRET) assays. Finally, a discussion of the potential for marketing successful aptamer-based assays or test kits is included.
Collapse
Affiliation(s)
- Tarun Kumar Sharma
- Center for Biodesign and Diagnostics, Translational Health Science and Technology Institute, Faridabad, Haryana 121001, India; AptaBharat Innovation Private Limited, Translational Health Science and Technology Institute Incubator, Haryana 121001, India.
| | - John G Bruno
- Operational Technologies Corporation, 4100 NW Loop 410, Suite, 230, San Antonio, TX 78229, USA..
| | - Abhijeet Dhiman
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi 110029, India.; Faculty of Pharmacy, Uttarakhand Technical University, Dehradun 248007, Uttarakhand, India
| |
Collapse
|
22
|
Barlev A, Sekhon GS, Bennet AJ, Sen D. DNA Repair by DNA: The UV1C DNAzyme Catalyzes Photoreactivation of Cyclobutane Thymine Dimers in DNA More Effectively than Their de Novo Formation. Biochemistry 2016; 55:6010-6018. [PMID: 27726378 DOI: 10.1021/acs.biochem.6b00951] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
UV1C, a 42-nt DNA oligonucleotide, is a deoxyribozyme (DNAzyme) that optimally uses 305 nm wavelength light to catalyze photoreactivation of a cyclobutane thymine dimer placed within a gapped, unnatural DNA substrate, TDP. Herein we show that UV1C is also capable of photoreactivating thymine dimers within an authentic single-stranded DNA substrate, LDP. This bona fide UV1C substrate enables, for the first time, investigation of whether UV1C catalyzes only photoreactivation or also the de novo formation of thymine dimers. Single-turnover experiments carried out with LDP and UV1C, relative to control experiments with LDP alone in single-stranded and double-stranded contexts, show that while UV1C does modestly promote thymine dimer formation, its major activity is indeed photoreactivation. Distinct photostationary states are reached for LDP in its three contexts: as a single strand, as a constituent of a double-helix, and as a 1:1 complex with UV1C. The above results on the cofactor-independent photoreactivation capabilities of a catalytic DNA reinforce a series of recent, unexpected reports that purely nucleotide-based photoreactivation is also operational within conventional double-helical DNA.
Collapse
Affiliation(s)
| | - Gurpreet S Sekhon
- Canary Center at Stanford for Cancer Early Detection, Department of Radiology, Stanford University, School of Medicine , Palo Alto, California 94304, United States
| | | | | |
Collapse
|
23
|
|