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Eberlein L, Beierlein FR, van Eikema Hommes NJR, Radadiya A, Heil J, Benner SA, Clark T, Kast SM, Richards NGJ. Tautomeric Equilibria of Nucleobases in the Hachimoji Expanded Genetic Alphabet. J Chem Theory Comput 2020; 16:2766-2777. [PMID: 32125859 DOI: 10.1021/acs.jctc.9b01079] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Evolution has yielded biopolymers that are constructed from exactly four building blocks and are able to support Darwinian evolution. Synthetic biology aims to extend this alphabet, and we recently showed that 8-letter (hachimoji) DNA can support rule-based information encoding. One source of replicative error in non-natural DNA-like systems, however, is the occurrence of alternative tautomeric forms, which pair differently. Unfortunately, little is known about how structural modifications impact free-energy differences between tautomers of the non-natural nucleobases used in the hachimoji expanded genetic alphabet. Determining experimental tautomer ratios is technically difficult, and so, strategies for improving hachimoji DNA replication efficiency will benefit from accurate computational predictions of equilibrium tautomeric ratios. We now report that high-level quantum-chemical calculations in aqueous solution by the embedded cluster reference interaction site model, benchmarked against free-energy molecular simulations for solvation thermodynamics, provide useful quantitative information on the tautomer ratios of both Watson-Crick and hachimoji nucleobases. In agreement with previous computational studies, all four Watson-Crick nucleobases adopt essentially only one tautomer in water. This is not the case, however, for non-natural nucleobases and their analogues. For example, although the enols of isoguanine and a series of related purines are not populated in water, these heterocycles possess N1-H and N3-H keto tautomers that are similar in energy, thereby adversely impacting accurate nucleobase pairing. These robust computational strategies offer a firm basis for improving experimental measurements of tautomeric ratios, which are currently limited to studying molecules that exist only as two tautomers in solution.
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Affiliation(s)
- Lukas Eberlein
- Physikalische Chemie III, Technische Universität Dortmund, Dortmund 44227, Germany
| | - Frank R Beierlein
- Computer-Chemistry-Centre and Interdisciplinary Centre for Molecular Materials, Department of Chemistry & Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 91054, Germany
| | - Nico J R van Eikema Hommes
- Computer-Chemistry-Centre and Interdisciplinary Centre for Molecular Materials, Department of Chemistry & Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 91054, Germany
| | - Ashish Radadiya
- School of Chemistry, Cardiff University, Cardiff CF10 3AT, U.K
| | - Jochen Heil
- Physikalische Chemie III, Technische Universität Dortmund, Dortmund 44227, Germany
| | - Steven A Benner
- Foundation for Applied Molecular Evolution, Alachua, Florida 32615, United States
| | - Timothy Clark
- Computer-Chemistry-Centre and Interdisciplinary Centre for Molecular Materials, Department of Chemistry & Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 91054, Germany
| | - Stefan M Kast
- Physikalische Chemie III, Technische Universität Dortmund, Dortmund 44227, Germany
| | - Nigel G J Richards
- School of Chemistry, Cardiff University, Cardiff CF10 3AT, U.K.,Foundation for Applied Molecular Evolution, Alachua, Florida 32615, United States
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2
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Karalkar NB, Benner SA. The challenge of synthetic biology. Synthetic Darwinism and the aperiodic crystal structure. Curr Opin Chem Biol 2018; 46:188-195. [PMID: 30098527 DOI: 10.1016/j.cbpa.2018.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 06/07/2018] [Accepted: 07/13/2018] [Indexed: 12/25/2022]
Abstract
'Grand Challenges' offer ways to discover flaws in existing theory without first needing to guess what those flaws are. Our grand challenge here is to reproduce the Darwinism of terran biology, but on molecular platforms different from standard DNA. Access to Darwinism distinguishes the living from the non-living state. However, theory suggests that any biopolymer able to support Darwinism must (a) be able to form Schrödinger's `aperiodic crystal', where different molecular components pack into a single crystal lattice, and (b) have a polyelectrolyte backbone. In 1953, the descriptive biology of Watson and Crick suggested DNA met Schrödinger's criertion, forming a linear crystal with geometrically similar building blocks supported on a polyelectrolye backbone. At the center of genetics were nucleobase pairs that fit into that crystal lattice by having both size complementarity and hydrogen bonding complementarity to enforce a constant geometry. This review covers experiments that show that by adhering to these two structural rules, the aperiodic crystal structure is maintained in DNA having 6 (or more) components. Further, this molecular system is shown to support Darwinism. Together with a deeper understanding of the role played in crystal formation by the poly-charged backbone and the intervening scaffolding, these results define how we might search for Darwinism, and therefore life, on Mars, Europa, Enceladus, and other watery lagoons in our Solar System.
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Affiliation(s)
- Nilesh B Karalkar
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Boulevard, Box 7, Alachua, FL 32615, United States
| | - Steven A Benner
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Boulevard, Box 7, Alachua, FL 32615, United States; Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, Box 17, Alachua, FL 32615, United States.
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3
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Wang X, Hoshika S, Peterson RJ, Kim MJ, Benner SA, Kahn JD. Biophysics of Artificially Expanded Genetic Information Systems. Thermodynamics of DNA Duplexes Containing Matches and Mismatches Involving 2-Amino-3-nitropyridin-6-one (Z) and Imidazo[1,2-a]-1,3,5-triazin-4(8H)one (P). ACS Synth Biol 2017; 6:782-792. [PMID: 28094993 DOI: 10.1021/acssynbio.6b00224] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Synthetic nucleobases presenting non-Watson-Crick arrangements of hydrogen bond donor and acceptor groups can form additional nucleotide pairs that stabilize duplex DNA independent of the standard A:T and G:C pairs. The pair between 2-amino-3-nitropyridin-6-one 2'-deoxyriboside (presenting a {donor-donor-acceptor} hydrogen bonding pattern on the Watson-Crick face of the small component, trivially designated Z) and imidazo[1,2-a]-1,3,5-triazin-4(8H)one 2'-deoxyriboside (presenting an {acceptor-acceptor-donor} hydrogen bonding pattern on the large component, trivially designated P) is one of these extra pairs for which a substantial amount of molecular biology has been developed. Here, we report the results of UV absorbance melting measurements and determine the energetics of binding of DNA strands containing Z and P to give short duplexes containing Z:P pairs as well as various mismatches comprising Z and P. All measurements were done at 1 M NaCl in buffer (10 mM Na cacodylate, 0.5 mM EDTA, pH 7.0). Thermodynamic parameters (ΔH°, ΔS°, and ΔG°37) for oligonucleotide hybridization were extracted. Consistent with the Watson-Crick model that considers both geometric and hydrogen bonding complementarity, the Z:P pair was found to contribute more to duplex stability than any mismatches involving either nonstandard nucleotide. Further, the Z:P pair is more stable than a C:G pair. The Z:G pair was found to be the most stable mismatch, forming either a deprotonated mismatched pair or a wobble base pair analogous to the stable T:G mismatch. The C:P pair is less stable, perhaps analogous to the wobble pair observed for C:O6-methyl-G, in which the pyrimidine is displaced into the minor groove. The Z:A and T:P mismatches are much less stable. Parameters for predicting the thermodynamics of oligonucleotides containing Z and P bases are provided. This represents the first case where this has been done for a synthetic genetic system.
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Affiliation(s)
- Xiaoyu Wang
- Department
of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Shuichi Hoshika
- Foundation for Applied Molecular Evolution, 13709 Progress Boulevard, No. 7, Alachua, Florida 32615, United States
| | - Raymond J. Peterson
- Celadon Laboratories, 6525 Belcrest
Road, Hyattsville, Maryland 20782, United States
| | - Myong-Jung Kim
- Foundation for Applied Molecular Evolution, 13709 Progress Boulevard, No. 7, Alachua, Florida 32615, United States
| | - Steven A. Benner
- Foundation for Applied Molecular Evolution, 13709 Progress Boulevard, No. 7, Alachua, Florida 32615, United States
- Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, No. 17, Alachua, Florida 32615, United States
| | - Jason D. Kahn
- Department
of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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Benner SA, Karalkar NB, Hoshika S, Laos R, Shaw RW, Matsuura M, Fajardo D, Moussatche P. Alternative Watson-Crick Synthetic Genetic Systems. Cold Spring Harb Perspect Biol 2016; 8:a023770. [PMID: 27663774 PMCID: PMC5088529 DOI: 10.1101/cshperspect.a023770] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In its "grand challenge" format in chemistry, "synthesis" as an activity sets out a goal that is substantially beyond current theoretical and technological capabilities. In pursuit of this goal, scientists are forced across uncharted territory, where they must answer unscripted questions and solve unscripted problems, creating new theories and new technologies in ways that would not be created by hypothesis-directed research. Thus, synthesis drives discovery and paradigm changes in ways that analysis cannot. Described here are the products that have arisen so far through the pursuit of one grand challenge in synthetic biology: Recreate the genetics, catalysis, evolution, and adaptation that we value in life, but using genetic and catalytic biopolymers different from those that have been delivered to us by natural history on Earth. The outcomes in technology include new diagnostic tools that have helped personalize the care of hundreds of thousands of patients worldwide. In science, the effort has generated a fundamentally different view of DNA, RNA, and how they work.
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Affiliation(s)
- Steven A Benner
- The Westheimer Institute for Science and Technology, The Foundation for Applied Molecular Evolution, Alachua, Florida 32615
| | - Nilesh B Karalkar
- The Westheimer Institute for Science and Technology, The Foundation for Applied Molecular Evolution, Alachua, Florida 32615
| | - Shuichi Hoshika
- The Westheimer Institute for Science and Technology, The Foundation for Applied Molecular Evolution, Alachua, Florida 32615
| | - Roberto Laos
- The Westheimer Institute for Science and Technology, The Foundation for Applied Molecular Evolution, Alachua, Florida 32615
| | - Ryan W Shaw
- The Westheimer Institute for Science and Technology, The Foundation for Applied Molecular Evolution, Alachua, Florida 32615
| | - Mariko Matsuura
- The Westheimer Institute for Science and Technology, The Foundation for Applied Molecular Evolution, Alachua, Florida 32615
| | - Diego Fajardo
- The Westheimer Institute for Science and Technology, The Foundation for Applied Molecular Evolution, Alachua, Florida 32615
| | - Patricia Moussatche
- The Westheimer Institute for Science and Technology, The Foundation for Applied Molecular Evolution, Alachua, Florida 32615
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5
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Karalkar NB, Leal NA, Kim MS, Bradley KM, Benner SA. Synthesis and Enzymology of 2'-Deoxy-7-deazaisoguanosine Triphosphate and Its Complement: A Second Generation Pair in an Artificially Expanded Genetic Information System. ACS Synth Biol 2016; 5:672-8. [PMID: 26914388 DOI: 10.1021/acssynbio.5b00276] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
As with natural nucleic acids, pairing between artificial nucleotides can be influenced by tautomerism, with different placements of protons on the heterocyclic nucleobase changing patterns of hydrogen bonding that determine replication fidelity. For example, the major tautomer of isoguanine presents a hydrogen bonding donor-donor-acceptor pattern complementary to the acceptor-acceptor-donor pattern of 5-methylisocytosine. However, in its minor tautomer, isoguanine presents a hydrogen bond donor-acceptor-donor pattern complementary to thymine. Calculations, crystallography, and physical organic experiments suggest that this tautomeric ambiguity might be "fixed" by replacing the N-7 nitrogen of isoguanine by a CH unit. To test this hypothesis, we prepared the triphosphate of 2'-deoxy-7-deazaiso-guanosine and used it in PCR to estimate an effective tautomeric ratio "seen" by Taq DNA polymerase. With 7-deazaisoguanine, fidelity-per-round was ∼92%. The analogous PCR with isoguanine gave a lower fidelity-per-round of ∼86%. These results confirm the hypothesis with polymerases, and deepen our understanding of the role of minor groove hydrogen bonding and proton tautomerism in both natural and expanded genetic "alphabets", major targets in synthetic biology.
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Affiliation(s)
- Nilesh B. Karalkar
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Boulevard, Box
7, Alachua, Florida 32615, United States
| | - Nicole A. Leal
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Boulevard, Box
7, Alachua, Florida 32615, United States
- Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, Box 17, Alachua, Florida 32615, United States
| | - Myong-Sang Kim
- Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, Box 17, Alachua, Florida 32615, United States
| | - Kevin M. Bradley
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Boulevard, Box
7, Alachua, Florida 32615, United States
| | - Steven A. Benner
- Foundation for Applied Molecular Evolution (FfAME), 13709 Progress Boulevard, Box
7, Alachua, Florida 32615, United States
- Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, Box 17, Alachua, Florida 32615, United States
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6
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Glushakova LG, Sharma N, Hoshika S, Bradley AC, Bradley KM, Yang Z, Benner SA. Detecting respiratory viral RNA using expanded genetic alphabets and self-avoiding DNA. Anal Biochem 2015; 489:62-72. [PMID: 26299645 PMCID: PMC4733849 DOI: 10.1016/j.ab.2015.08.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 08/07/2015] [Accepted: 08/13/2015] [Indexed: 11/23/2022]
Abstract
Nucleic acid (NA)-targeted tests detect and quantify viral DNA and RNA (collectively xNA) to support epidemiological surveillance and, in individual patients, to guide therapy. They commonly use polymerase chain reaction (PCR) and reverse transcription PCR. Although these all have rapid turnaround, they are expensive to run. Multiplexing would allow their cost to be spread over multiple targets, but often only with lower sensitivity and accuracy, noise, false positives, and false negatives; these arise by interactions between the multiple nucleic acid primers and probes in a multiplexed kit. Here we offer a multiplexed assay for a panel of respiratory viruses that mitigates these problems by combining several nucleic acid analogs from the emerging field of synthetic biology: (i) self-avoiding molecular recognition systems (SAMRSs), which facilitate multiplexing, and (ii) artificially expanded genetic information systems (AEGISs), which enable low-noise PCR. These are supplemented by “transliteration” technology, which converts standard nucleotides in a target to AEGIS nucleotides in a product, improving hybridization. The combination supports a multiplexed Luminex-based respiratory panel that potentially differentiates influenza viruses A and B, respiratory syncytial virus, severe acute respiratory syndrome coronavirus (SARS), and Middle East respiratory syndrome (MERS) coronavirus, detecting as few as 10 MERS virions in a 20-μl sample.
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Affiliation(s)
| | - Nidhi Sharma
- Foundation for Applied Molecular Evolution (FfAME), Alachua, FL 32615, USA
| | - Shuichi Hoshika
- Foundation for Applied Molecular Evolution (FfAME), Alachua, FL 32615, USA
| | - Andrea C Bradley
- Foundation for Applied Molecular Evolution (FfAME), Alachua, FL 32615, USA
| | - Kevin M Bradley
- Foundation for Applied Molecular Evolution (FfAME), Alachua, FL 32615, USA
| | - Zunyi Yang
- Foundation for Applied Molecular Evolution (FfAME), Alachua, FL 32615, USA
| | - Steven A Benner
- Firebird Biomolecular Sciences, Alachua, FL 32615, USA; Foundation for Applied Molecular Evolution (FfAME), Alachua, FL 32615, USA.
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7
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Laos R, Thomson JM, Benner SA. DNA polymerases engineered by directed evolution to incorporate non-standard nucleotides. Front Microbiol 2014; 5:565. [PMID: 25400626 PMCID: PMC4215692 DOI: 10.3389/fmicb.2014.00565] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 10/07/2014] [Indexed: 11/13/2022] Open
Abstract
DNA polymerases have evolved for billions of years to accept natural nucleoside triphosphate substrates with high fidelity and to exclude closely related structures, such as the analogous ribonucleoside triphosphates. However, polymerases that can accept unnatural nucleoside triphosphates are desired for many applications in biotechnology. The focus of this review is on non-standard nucleotides that expand the genetic "alphabet." This review focuses on experiments that, by directed evolution, have created variants of DNA polymerases that are better able to accept unnatural nucleotides. In many cases, an analysis of past evolution of these polymerases (as inferred by examining multiple sequence alignments) can help explain some of the mutations delivered by directed evolution.
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Affiliation(s)
- Roberto Laos
- Foundation for Applied Molecular Evolution Gainesville, FL, USA
| | | | - Steven A Benner
- Foundation for Applied Molecular Evolution Gainesville, FL, USA
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8
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Kopyra J, Freza S, Abdoul-Carime H, Marchaj M, Skurski P. Dissociative electron attachment to gas phase thiothymine: experimental and theoretical approaches. Phys Chem Chem Phys 2014; 16:5342-8. [DOI: 10.1039/c3cp54966f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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9
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Kopyra J, Abdoul-Carime H, Kossoski F, Varella MTDN. Electron driven reactions in sulphur containing analogues of uracil: the case of 2-thiouracil. Phys Chem Chem Phys 2014; 16:25054-61. [DOI: 10.1039/c4cp03544e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron induced fragmentation of 2-thiouracil.
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Affiliation(s)
- J. Kopyra
- Chemistry Department
- Siedlce University
- 08-110 Siedlce, Poland
| | - H. Abdoul-Carime
- Université de Lyon
- Université Lyon 1
- CNRS/IN2P3
- UMR5822
- Institut de Physique Nucléaire de Lyon
| | - F. Kossoski
- Instituto de Fisica
- Universidade de São Paulo
- 05314-970 São Paulo, Brazil
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10
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XNA marks the spot. What can we learn about the origins of life and the treatment of disease through artificial nucleic acids? EMBO Rep 2013; 14:410-3. [PMID: 23579343 DOI: 10.1038/embor.2013.42] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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11
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Yang Z, Chen F, Alvarado JB, Benner SA. Amplification, mutation, and sequencing of a six-letter synthetic genetic system. J Am Chem Soc 2011; 133:15105-12. [PMID: 21842904 DOI: 10.1021/ja204910n] [Citation(s) in RCA: 184] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The next goals in the development of a synthetic biology that uses artificial genetic systems will require chemistry-biology combinations that allow the amplification of DNA containing any number of sequential and nonsequential nonstandard nucleotides. This amplification must ensure that the nonstandard nucleotides are not unidirectionally lost during PCR amplification (unidirectional loss would cause the artificial system to revert to an all-natural genetic system). Further, technology is needed to sequence artificial genetic DNA molecules. The work reported here meets all three of these goals for a six-letter artificially expanded genetic information system (AEGIS) that comprises four standard nucleotides (G, A, C, and T) and two additional nonstandard nucleotides (Z and P). We report polymerases and PCR conditions that amplify a wide range of GACTZP DNA sequences having multiple consecutive unnatural synthetic genetic components with low (0.2% per theoretical cycle) levels of mutation. We demonstrate that residual mutation processes both introduce and remove unnatural nucleotides, allowing the artificial genetic system to evolve as such, rather than revert to a wholly natural system. We then show that mechanisms for these residual mutation processes can be exploited in a strategy to sequence "six-letter" GACTZP DNA. These are all not yet reported for any other synthetic genetic system.
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Affiliation(s)
- Zunyi Yang
- Foundation for Applied Molecular Evolution (FfAME), Gainesville, Florida 32601, United States
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12
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Association of MnSOD Ala16Val genotype and activity with hepatocellular carcinoma risk in HCV-infected Egyptian patients. Arab J Gastroenterol 2010. [DOI: 10.1016/j.ajg.2010.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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13
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Abstract
Integrative biology currently undergoes a deep renewal as we witness the increasing influence of systems biology, which explores life's logic, and of synthetic biology, which exploits it.
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14
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Stomel JM, Wilson JW, León MA, Stafford P, Chaput JC. A man-made ATP-binding protein evolved independent of nature causes abnormal growth in bacterial cells. PLoS One 2009; 4:e7385. [PMID: 19812699 PMCID: PMC2754611 DOI: 10.1371/journal.pone.0007385] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Accepted: 09/15/2009] [Indexed: 11/18/2022] Open
Abstract
Recent advances in de novo protein evolution have made it possible to create synthetic proteins from unbiased libraries that fold into stable tertiary structures with predefined functions. However, it is not known whether such proteins will be functional when expressed inside living cells or how a host organism would respond to an encounter with a non-biological protein. Here, we examine the physiology and morphology of Escherichia coli cells engineered to express a synthetic ATP-binding protein evolved entirely from non-biological origins. We show that this man-made protein disrupts the normal energetic balance of the cell by altering the levels of intracellular ATP. This disruption cascades into a series of events that ultimately limit reproductive competency by inhibiting cell division. We now describe a detailed investigation into the synthetic biology of this man-made protein in a living bacterial organism, and the effect that this protein has on normal cell physiology.
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Affiliation(s)
- Joshua M. Stomel
- Center for BioOptical Nanotechnology, Arizona State University, Tempe, Arizona, United States of America
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - James W. Wilson
- Center for Infectious Disease and Vaccinology, Arizona State University, Tempe, Arizona, United States of America
| | - Megan A. León
- Center for BioOptical Nanotechnology, Arizona State University, Tempe, Arizona, United States of America
| | - Phillip Stafford
- Center for Innovations in Medicine, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - John C. Chaput
- Center for BioOptical Nanotechnology, Arizona State University, Tempe, Arizona, United States of America
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, United States of America
- * E-mail:
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15
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Performance of the Abbott real-time PCR assay using m2000sp and m2000rt for hepatitis C virus RNA quantification. J Clin Microbiol 2009; 47:1726-32. [PMID: 19369435 DOI: 10.1128/jcm.01300-08] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Quantification of hepatitis C virus (HCV) RNA is essential for the everyday management of chronic hepatitis C therapy. "Real-time" PCR techniques are potentially more sensitive than classical PCR techniques, are not prone to carryover contamination, and have a consistently wider dynamic range of quantification. Thus, they are rapidly replacing other technologies for routine quantification of HCV RNA. We extensively evaluated the intrinsic characteristics and clinical performance of the m2000(sp)-m2000(rt) Abbott real-time PCR platform for HCV RNA quantification. The study shows that the m2000(sp)-m2000(rt) platform is sensitive, specific, and precise; that the results are reproducible; and that the platform has a broad dynamic range of quantification. When comparing HCV RNA levels measured in the same individuals with the m2000(sp)-m2000(rt) platform and the third-generation branched-DNA assay, a trend toward a modest overestimation of HCV RNA levels was observed in the m2000(sp)-m2000(rt) platform in all genotypes except genotype 5. The differences, however, were unlikely to have any impact in clinical practice. In conclusion, our study shows that the Abbott m2000 real-time PCR system for HCV RNA quantification is sensitive, specific, and precise; that the results are reproducible; and that the platform's broad dynamic range of quantification is well suited to HCV RNA monitoring in the clinical setting.
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16
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Kim HJ, Leal NA, Benner SA. 2'-deoxy-1-methylpseudocytidine, a stable analog of 2'-deoxy-5-methylisocytidine. Bioorg Med Chem 2009; 17:3728-32. [PMID: 19394831 DOI: 10.1016/j.bmc.2009.03.047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Revised: 03/20/2009] [Accepted: 03/22/2009] [Indexed: 10/21/2022]
Abstract
2'-deoxy-5-methylisocytidine is widely used in assays to personalize the care of patients infected with HIV, hepatitis C, and other infectious agents. However, oligonucleotides that incorporate 2'-deoxy-5-methylisocytidine are expensive, because of its intrinsic chemical instability. We report here a C-glycoside analog that is more stable and, in oligonucleotides, pairs with 2'-deoxyisoguanosine, contributing to duplex stability about as much as a standard 2'-deoxycytidine and 2'-deoxyguanosine pair.
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Affiliation(s)
- Hyo-Joong Kim
- Westheimer Institute for Science and Technology, Foundation for Applied Molecular Evolution, PO Box 13174, Gainesville, FL 32604, USA
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17
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Elbeik T, Dalessandro R, Loftus RA, Beringer S. HIV-1 and HCV viral load cost models for bDNA: 440 Molecular System versus real-time PCR AmpliPrep/TaqMan test. Expert Rev Mol Diagn 2008; 7:723-53. [PMID: 18020903 DOI: 10.1586/14737159.7.6.723] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Comparative cost models were developed to assess cost-per-reportable result and annual costs for HIV-1 and HCV bDNA and AmpliPrep/TaqMan Test (PCR). Model cost components included kit, disposables, platform and related equipment, equipment service plan, equipment maintenance, equipment footprint, waste and labor. Model assessment was most cost-effective when run by bDNA with 36 or more clinical samples and PCR with 30 or fewer clinical samples. Lower costs are attained with maximum samples (84-168) run daily. Highest cost contributors include kit, platform and PCR proprietary disposables. Understanding component costs and the most economic use of HIV-1 and HCV viral load will aid in attaining lowest costs through selection of the appropriate assay and effective negotiations.
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Affiliation(s)
- Tarek Elbeik
- Professional Habitat Design, LLC; Health Management Institute, Inc, c/o 584 Castro Street #349, San Francisco, CA 94114, USA.
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18
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Chevaliez S, Bouvier-Alias M, Brillet R, Pawlotsky JM. Overestimation and underestimation of hepatitis C virus RNA levels in a widely used real-time polymerase chain reaction-based method. Hepatology 2007; 46:22-31. [PMID: 17525931 DOI: 10.1002/hep.21656] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
UNLABELLED The quantification of hepatitis C virus (HCV) RNA is essential for the everyday management of chronic hepatitis C therapy. Real-time polymerase chain reaction (PCR) techniques are potentially more sensitive than classical PCR techniques, are not prone to carryover contamination, and have a consistently wider dynamic range of quantification. Thus, they are rapidly replacing other technologies for the routine quantification of HCV RNA. We extensively evaluated the intrinsic characteristics and clinical performance of Cobas Ampliprep/Cobas TaqMan (CAP/CTM), the most widely used real-time PCR assay for HCV RNA quantification. This study shows that CAP/CTM is sensitive, specific, precise, and reproducible and has a broad dynamic range of quantification well suited to HCV RNA monitoring in clinical practice. However, we identified 2 technical issues that will have an impact in clinical practice. First, the CAP/CTM assay overestimates HCV RNA levels in undiluted patient samples by approximately 0.6 log(10) international units per milliliter on average, and this overestimation increases with the viral load. Second, the CAP/CTM assay substantially underestimates HCV RNA levels in approximately 15% of genotype 2 samples and 30% of genotype 4 samples, probably because of mismatches with the target sequences due to the primer and/or probe design. CONCLUSION As the CAP/CTM platform is widely available, easy to use, and suited to high-throughput screening for viral genomes, the manufacturer should improve the HCV RNA kit to resolve these 2 important technical issues that may affect everyday management of hepatitis C therapy.
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Affiliation(s)
- Stéphane Chevaliez
- French National Reference Center for Viral Hepatitis B, C, and Delta, Department of Virology, Hôpital Henri Mondor, Créteil, France
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Highbarger HC, Hu Z, Kottilil S, Metcalf JA, Polis MA, Vasudevachari MB, Lane HC, Dewar RL. Comparison of the abbott 7000 and bayer 340 systems for measurement of hepatitis C virus load. J Clin Microbiol 2007; 45:2808-12. [PMID: 17596352 PMCID: PMC2045268 DOI: 10.1128/jcm.00202-07] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study compared two commercially available assays for the measurement of hepatitis C virus (HCV) RNA levels, the Bayer HCV RNA (version 3.0) branched DNA assay and the Abbott HCV analyte-specific reagent real-time PCR assay, to assess their quantitative relationships, ease of performance, and time to completion. The study group consisted of randomly selected patients from the NIAID human immunodeficiency virus (HIV) outpatient clinic who were infected with HIV type 1 and HCV. One hundred eighty-four samples from 66 patients coinfected with HIV and HCV receiving treatments under various protocols were analyzed for the correlation and agreement of the results. The results indicated that the two assays correlate well in the overlapping linear ranges of the assays and show good agreement. From the results obtained, we have derived a mathematical formula to compare the viral load results between the two assays, which is given as log(10) Abbott assay measure = 0.032 + 1.01 log(10) Bayer assay measure. Although it is preferable to use the same quantitation assay throughout the course of a patient's treatment, valid comparisons of the HCV RNA levels may be made between the results obtained by either of these assays in the overlapping linear range (615 to 7,700,000 IU/ml).
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Affiliation(s)
- Helene C Highbarger
- Virus Isolation and Serology Laboratory, SAIC--Frederick, Inc., NCI--Frederick, Frederick, MD 21702, USA.
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20
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Wellington KW, Benner SA. A review: synthesis of aryl C-glycosides via the heck coupling reaction. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2007; 25:1309-33. [PMID: 17067955 DOI: 10.1080/15257770600917013] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In this article, we focus on the synthesis of aryl C-glycosides via Heck coupling. It is organized based on the type of structures used in the assembly of the C-glycosides (also called C-nucleosides) with the following subsections: pyrimidine C-nucleosides, purine C-nucleosides, and monocyclic, bicyclic, and tetracyclic C-nucleosides. The reagents and conditions used for conducting the Heck coupling reactions are discussed. The subsequent conversion of the Heck products to the corresponding target molecules and the application of the target molecules are also described.
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Affiliation(s)
- Kevin W Wellington
- Foundation for Applied Molecular Evolution, Gainesville, Florida 32604, USA
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21
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Abstract
Infection with HIV and subsequent development of AIDS is a pandemic. The Joint United Nations Program on HIV/AIDS together with the WHO and many relevant funding bodies demand that those infected should be reliably identified so that people who need, or will need, therapy may be provided for over time. This means that there is a renewed interest in testing for HIV and in laboratories' performances and quality. Whatever the conditions under which testing is performed, and whatever the levels of training, the tests and their outcomes must exhibit equivalent, high standards of performance and reliable results. This is regardless of whether testing is conducted in the most sophisticated laboratories (either diagnostic or transfusion screening) to voluntary testing and counseling centers where those conducting testing may not be technically trained. This is not currently the case, especially in some places where HIV is most prevalent. To achieve uniformly high performance standards, quality assurance programs are imperative, but currently not sufficiently valued to be well supported with adequate funding or human resources. Accurate HIV testing is a cornerstone of blood safety, diagnosis of infection, patient management and surveillance.
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Affiliation(s)
- Denison Chang
- World Health Organization Collaborating Centre on HIV/AIDS, Fitzroy, Victoria, Australia.
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22
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El Awady MK, El Abd YS, Shoeb HA, Tabll AA, Hosny AEDMS, El Shenawy RM, Atef K, Bader El Din NG, Bahgat MM. Circulating viral core and E1 antigen levels as supplemental markers for HCV chronic hepatitis. Virol J 2006; 3:67. [PMID: 16948845 PMCID: PMC1586018 DOI: 10.1186/1743-422x-3-67] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Accepted: 09/01/2006] [Indexed: 02/07/2023] Open
Abstract
The performance of polyclonal monospecific rabbit anti-sera raised against synthetic peptides derived from conserved HCV sequences of genotype 4 was evaluated for efficient detection of viral core and E1 antigens in circulating immune complexes (ICs) precipitated from 65 serum samples of HCV patients. The infection was established in those patients by the presence of HCV RNA in their sera. A novel enzyme-linked immunosorbent assay (ELISA) was developed for the detection of HCV core and E1 antigen in serum samples. Western blot analyses were used to demonstrate the presence of the core and E1 target antigen in serum samples. The mean OD readings of both core and E1 antigens were significantly higher (P < 0.05) among the viremic patients when compared to controls. Also a significant positive correlation (P < 0.05, r = 0.98) between the values of both core and E1 was recorded. Western blot analysis based on monospecific antibodies against core and E1 recognized the 38-kDa and 88 -kDa bands respectively in the sera of all infected patients. No specific reaction was observed with the sera from uninfected individuals. Interestingly the results of core and E1 antigen levels displayed no positive correlation with the HCV copy number as measured by bDNA. Liver enzymes (ALT and AST) showed a moderate positive correlation (r = 0.44 and 0.47 respectively) with the viral core antigens level. The same trend holds true for E1 (r = 0.43 and 0.64 for ALT and AST respectively). HCV load in infected patients revealed extremely poor correlation with serum ALT and AST levels (r = 0.022 and 0.002 respectively). In conclusion we present a new combination of serological tools correlating with liver enzyme levels that could be utilized as supplemental tests to viral load testing. Also, a sensitive and specific immunoassay was developed for the detection of HCV core and E1 in human serum. This test can be applied for laboratory diagnosis of HCV infection.
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Affiliation(s)
- Mostafa K El Awady
- Department of Biomedical Technology, the National Research Center, Dokki, Egypt
| | - Yasmine S El Abd
- Department of Biomedical Technology, the National Research Center, Dokki, Egypt
| | - Hussein A Shoeb
- Department of Microbiology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Ashraf A Tabll
- Department of Biomedical Technology, the National Research Center, Dokki, Egypt
| | | | - Reem M El Shenawy
- Department of Biomedical Technology, the National Research Center, Dokki, Egypt
| | - Khaled Atef
- Department of Biomedical Technology, the National Research Center, Dokki, Egypt
| | - Noha G Bader El Din
- Department of Biomedical Technology, the National Research Center, Dokki, Egypt
| | - Mahmoud M Bahgat
- Department of Medicinal Chemistry, the National Research Center, Dokki, Giza, Egypt
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23
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El Awady MK, El Abd YS, Shoeb HA, Tabll AA, Hosny AEDMS, El Shenawy RM, Atef K, Bader El Din NG, Bahgat MM. Circulating viral core and E1 antigen levels as supplemental markers for HCV chronic hepatitis. Virol J 2006. [PMID: 16948845 DOI: 10.1186/1743-422x-3-67.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The performance of polyclonal monospecific rabbit anti-sera raised against synthetic peptides derived from conserved HCV sequences of genotype 4 was evaluated for efficient detection of viral core and E1 antigens in circulating immune complexes (ICs) precipitated from 65 serum samples of HCV patients. The infection was established in those patients by the presence of HCV RNA in their sera. A novel enzyme-linked immunosorbent assay (ELISA) was developed for the detection of HCV core and E1 antigen in serum samples. Western blot analyses were used to demonstrate the presence of the core and E1 target antigen in serum samples. The mean OD readings of both core and E1 antigens were significantly higher (P < 0.05) among the viremic patients when compared to controls. Also a significant positive correlation (P < 0.05, r = 0.98) between the values of both core and E1 was recorded. Western blot analysis based on monospecific antibodies against core and E1 recognized the 38-kDa and 88 -kDa bands respectively in the sera of all infected patients. No specific reaction was observed with the sera from uninfected individuals. Interestingly the results of core and E1 antigen levels displayed no positive correlation with the HCV copy number as measured by bDNA. Liver enzymes (ALT and AST) showed a moderate positive correlation (r = 0.44 and 0.47 respectively) with the viral core antigens level. The same trend holds true for E1 (r = 0.43 and 0.64 for ALT and AST respectively). HCV load in infected patients revealed extremely poor correlation with serum ALT and AST levels (r = 0.022 and 0.002 respectively). In conclusion we present a new combination of serological tools correlating with liver enzyme levels that could be utilized as supplemental tests to viral load testing. Also, a sensitive and specific immunoassay was developed for the detection of HCV core and E1 in human serum. This test can be applied for laboratory diagnosis of HCV infection.
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Affiliation(s)
- Mostafa K El Awady
- Department of Biomedical Technology, the National Research Center, Dokki, Egypt.
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24
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Abstract
Viral quantification or viral load testing has become part of the routine management of patients infected with HIV-1 or hepatitis C virus (HCV). There are currently several molecular technologies that are available for use in the clinical laboratory setting. Of these, only the branched DNA (bDNA) assays are FDA-approved for HIV-1 and HCV viral load testing. This signal amplification technology is built on a series of hybridization reactions that are highly amenable to full automation and thus lessen the amount of labor required to perform this type of analysis. This article provides a historical perspective of bDNA and its clinical applications.
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Affiliation(s)
- Gregory J Tsongalis
- Department of Pathology, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA
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25
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Sismour AM, Benner SA. The use of thymidine analogs to improve the replication of an extra DNA base pair: a synthetic biological system. Nucleic Acids Res 2005; 33:5640-6. [PMID: 16192575 PMCID: PMC1236980 DOI: 10.1093/nar/gki873] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Synthetic biology based on a six-letter genetic alphabet that includes the two non-standard nucleobases isoguanine (isoG) and isocytosine (isoC), as well as the standard A, T, G and C, is known to suffer as a consequence of a minor tautomeric form of isoguanine that pairs with thymine, and therefore leads to infidelity during repeated cycles of the PCR. Reported here is a solution to this problem. The solution replaces thymidine triphosphate by 2-thiothymidine triphosphate (2-thioTTP). Because of the bulk and hydrogen bonding properties of the thione unit in 2-thioT, 2-thioT does not mispair effectively with the minor tautomer of isoG. To test whether this might allow PCR amplification of a six-letter artificially expanded genetic information system, we examined the relative rates of misincorporation of 2-thioTTP and TTP opposite isoG using affinity electrophoresis. The concentrations of isoCTP and 2-thioTTP were optimal to best support PCR amplification using thermostable polymerases of a six-letter alphabet that includes the isoC–isoG pair. The fidelity-per-round of amplification was found to be ∼98% in trial PCRs with this six-letter DNA alphabet. The analogous PCR employing TTP had a fidelity-per-round of only ∼93%. Thus, the A, 2-thioT, G, C, isoC, isoG alphabet is an artificial genetic system capable of Darwinian evolution.
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Affiliation(s)
- A Michael Sismour
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
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Abstract
Synthetic biologists come in two broad classes. One uses unnatural molecules to reproduce emergent behaviours from natural biology, with the goal of creating artificial life. The other seeks interchangeable parts from natural biology to assemble into systems that function unnaturally. Either way, a synthetic goal forces scientists to cross uncharted ground to encounter and solve problems that are not easily encountered through analysis. This drives the emergence of new paradigms in ways that analysis cannot easily do. Synthetic biology has generated diagnostic tools that improve the care of patients with infectious diseases, as well as devices that oscillate, creep and play tic-tac-toe.
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Affiliation(s)
- Steven A Benner
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
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