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Fochtman TJ, Oza JP. Established and Emerging Methods for Protecting Linear DNA in Cell-Free Expression Systems. Methods Protoc 2023; 6:mps6020036. [PMID: 37104018 PMCID: PMC10146267 DOI: 10.3390/mps6020036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/17/2023] [Accepted: 03/21/2023] [Indexed: 04/03/2023] Open
Abstract
Cell-free protein synthesis (CFPS) is a method utilized for producing proteins without the limits of cell viability. The plug-and-play utility of CFPS is a key advantage over traditional plasmid-based expression systems and is foundational to the potential of this biotechnology. A key limitation of CFPS is the varying stability of DNA types, limiting the effectiveness of cell-free protein synthesis reactions. Researchers generally rely on plasmid DNA for its ability to support robust protein expression in vitro. However, the overhead required to clone, propagate, and purify plasmids reduces the potential of CFPS for rapid prototyping. While linear templates overcome the limits of plasmid DNA preparation, linear expression templates (LETs) were under-utilized due to their rapid degradation in extract based CFPS systems, limiting protein synthesis. To reach the potential of CFPS using LETs, researchers have made notable progress toward protection and stabilization of linear templates throughout the reaction. The current advancements range from modular solutions, such as supplementing nuclease inhibitors and genome engineering to produce strains lacking nuclease activity. Effective application of LET protection techniques improves expression yields of target proteins to match that of plasmid-based expression. The outcome of LET utilization in CFPS is rapid design–build–test–learn cycles to support synthetic biology applications. This review describes the various protection mechanisms for linear expression templates, methodological insights for implementation, and proposals for continued efforts that may further advance the field.
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Chandrasekaran AR, Vilcapoma J, Dey P, Wong-Deyrup SW, Dey BK, Halvorsen K. Exceptional Nuclease Resistance of Paranemic Crossover (PX) DNA and Crossover-Dependent Biostability of DNA Motifs. J Am Chem Soc 2020; 142:6814-6821. [PMID: 32208657 DOI: 10.1021/jacs.0c02211] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Nanometer-sized features and molecular recognition properties make DNA a useful material for nanoscale construction, but degradation in biological fluids poses a considerable roadblock to biomedical applications of DNA nanotechnology. Here, we report the remarkable biostability of a multistranded motif called paranemic crossover (PX) DNA. Compared to double stranded DNA, PX DNA has dramatically enhanced (sometimes >1000 fold) resistance to degradation by four different nucleases, bovine and human serum, and human urine. We trace the cause of PX's biostability to DNA crossovers, showing a continuum of protection that scales with the number of crossovers. These results suggest that enhanced biostability can be engineered into DNA nanostructures by adopting PX-based architectures or by strategic crossover placement.
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Affiliation(s)
- Arun Richard Chandrasekaran
- The RNA Institute, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Javier Vilcapoma
- The RNA Institute, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Paromita Dey
- The RNA Institute, University at Albany, State University of New York, Albany, New York 12222, United States.,Department of Biological Sciences, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Siu Wah Wong-Deyrup
- The RNA Institute, University at Albany, State University of New York, Albany, New York 12222, United States.,Department of Biological Sciences, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Bijan K Dey
- The RNA Institute, University at Albany, State University of New York, Albany, New York 12222, United States.,Department of Biological Sciences, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Ken Halvorsen
- The RNA Institute, University at Albany, State University of New York, Albany, New York 12222, United States
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Gladyshev E, Kleckner N. Recombination-Independent Recognition of DNA Homology for Repeat-Induced Point Mutation (RIP) Is Modulated by the Underlying Nucleotide Sequence. PLoS Genet 2016; 12:e1006015. [PMID: 27148882 PMCID: PMC4858203 DOI: 10.1371/journal.pgen.1006015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 04/06/2016] [Indexed: 11/18/2022] Open
Abstract
Haploid germline nuclei of many filamentous fungi have the capacity to detect homologous nucleotide sequences present on the same or different chromosomes. Once recognized, such sequences can undergo cytosine methylation or cytosine-to-thymine mutation specifically over the extent of shared homology. In Neurospora crassa this process is known as Repeat-Induced Point mutation (RIP). Previously, we showed that RIP did not require MEI-3, the only RecA homolog in Neurospora, and that it could detect homologous trinucleotides interspersed with a matching periodicity of 11 or 12 base-pairs along participating chromosomal segments. This pattern was consistent with a mechanism of homology recognition that involved direct interactions between co-aligned double-stranded (ds) DNA molecules, where sequence-specific dsDNA/dsDNA contacts could be established using no more than one triplet per turn. In the present study we have further explored the DNA sequence requirements for RIP. In our previous work, interspersed homologies were always examined in the context of a relatively long adjoining region of perfect homology. Using a new repeat system lacking this strong interaction, we now show that interspersed homologies with overall sequence identity of only 36% can be efficiently detected by RIP in the absence of any perfect homology. Furthermore, in this new system, where the total amount of homology is near the critical threshold required for RIP, the nucleotide composition of participating DNA molecules is identified as an important factor. Our results specifically pinpoint the triplet 5'-GAC-3' as a particularly efficient unit of homology recognition. Finally, we present experimental evidence that the process of homology sensing can be uncoupled from the downstream mutation. Taken together, our results advance the notion that sequence information can be compared directly between double-stranded DNA molecules during RIP and, potentially, in other processes where homologous pairing of intact DNA molecules is observed.
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Affiliation(s)
- Eugene Gladyshev
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (EG); (NK)
| | - Nancy Kleckner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (EG); (NK)
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Ren J, Wang T, Wang E, Wang J. I-motif-stapled and spacer-dependent multiple DNA nanostructures. RSC Adv 2016. [DOI: 10.1039/c6ra15201e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The DNA spacers between duplexes and i-motif structures are critical for the morphology of assembled pH-responsive DNA nanostructures, which is very instructive for fabrication of distinct-scale molecular devices in the future.
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Affiliation(s)
- Jiangtao Ren
- State Key Laboratory of Electroanalytical Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun
- China
| | - Tianshu Wang
- State Key Laboratory of Electroanalytical Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun
- China
| | - Erkang Wang
- State Key Laboratory of Electroanalytical Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun
- China
| | - Jin Wang
- State Key Laboratory of Electroanalytical Chemistry
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun
- China
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