A comparison between the efficiency of recombinase-mediated cassette exchange (RMCE) reactions catalyzed in Escherichia coli by the site-specific recombinases Flp of yeast and Int of coliphage HK022 has revealed that an Flp-catalyzed RMCE reaction is more efficient than an Int-HK022 catalyzed reaction. In contrast, an RMCE reaction with 1 pair of frt sites and 1 pair of att sites catalyzed in the presence of both recombinases is very inefficient. However, the same reaction catalyzed by each recombinase individually supplied in a sequential order is very efficient, regardless of the order. Atomic force microscopy images of Flp with its DNA substrates show that only 1 pair of recombination sites forms a synaptic complex with the recombinase. The results suggest that the RMCE reaction is sequential.
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http://dx.doi.org/10.1159/000321497 | DOI Listing |
Nucleic Acids Res
December 2020
Department of Biochemistry and Molecular Biology, School of Neurobiology, Biochemistry &Biophysics, Tel-Aviv University, Tel-Aviv, Israel.
HK022 coliphage site-specific recombinase Integrase (Int) can catalyze integrative site-specific recombination and recombinase-mediated cassette exchange (RMCE) reactions in mammalian cell cultures. Owing to the promiscuity of the 7 bp overlap sequence in its att sites, active 'attB' sites flanking human deleterious mutations were previously identified that may serve as substrates for RMCE reactions for future potential gene therapy. However, the wild type Int proved inefficient in catalyzing such RMCE reactions.
View Article and Find Full Text PDFMolecules
October 2018
Centre for Synthetic Biology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Gent, Belgium.
Cellobiose 2-epimerase from (CE) reversibly converts a glucose residue to a mannose residue at the reducing end of β-1,4-linked oligosaccharides. In this study, the monosaccharide specificity of CE has been mapped and the synthesis of d-talose from d-galactose was discovered, a reaction not yet known to occur in nature. Moreover, the conversion is industrially relevant, as talose and its derivatives have been reported to possess important antimicrobial and anti-inflammatory properties.
View Article and Find Full Text PDFBiotechnol Rep (Amst)
September 2018
Institute of Bioprocess Engineering and Pharmaceutical Technology, University of Applied Sciences Mittelhessen, Giessen, Germany.
The generation of monoclonal cell lines is an important early process development step for recombinant protein production. Although single-cell cloning is an established method in mammalian cell lines, straightforward protocols are not yet available for insect cells. We describe a new method for the generation of monoclonal insect cells without using fetal bovine serum and/or feeder cells pretreated by irradiation or exposure to mitomycin.
View Article and Find Full Text PDFMethods Mol Biol
April 2018
Department of Genetics, Stanford University School of Medicine, 300 Pasteur Drive, Alway Building, M316, Stanford, CA, 94305-5120, USA.
When constructing transgenic cell lines via plasmid DNA integration, precise targeting to a desired genomic location is advantageous. It is also often advantageous to remove the bacterial backbone, since bacterial elements can lead to the epigenetic silencing of neighboring DNA. The least cumbersome method to remove the plasmid backbone is recombinase-mediated cassette exchange (RMCE).
View Article and Find Full Text PDFMethods Mol Biol
April 2018
School of Biosciences, Louisiana Tech University, 1 Adams Blvd, Ruston, LA, 71272, USA.
Recombinase-mediated cassette exchange, or RMCE, is a genome engineering tool that can be used to swap DNA fragments of interest between two DNA molecules. In a variation of RMCE, called dual RMCE, the exchange of DNA fragments is mediated by two recombinases in contrast to one recombinase in the classic RMCE reaction. Under optimal conditions, the efficiency of dual RMCE can be quite high: up to ~45% of the transfected cells depending on the recombinase pair used to mediate the replacement reaction.
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