title: En passant mutagenesis: a two step markerless red recombination system.
abstract: Bacterial artificial chromosomes are used to maintain and modify large sequences of different origins in Escherichia coli. In addition to RecA-based shuttle mutagenesis, Red recombination is commonly used for sequence modification. Since foreign sequences, such as antibiotic resistance genes as well as frt- or loxP-sites are often unwanted in mutant BAC clones, we developed a Red-based technique that allows for the scarless generation of point mutations, deletions, and insertion of smaller and larger sequences. The method employs a sequence duplication that is inserted into the target sequence in the first recombination step and the excision of the selection marker by in vivo I-SceI cleavage and the second Red recombination. To allow for convenient and highly efficient mutagenesis without the use of additional plasmids, the E. coli strain GS1783 with a chromosomal encoded inducible Red- and I-SceI-expression was created.
authors.affiliation: Institut für Virologie, Freie Universität Berlin, Berlin, Germany. k.tischer@fu-berlin.de
authors.forename: B Karsten
authors.initials: BK
authors.lastname: Tischer
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Smith
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Osterrieder
mesh_terms: D022202:Chromosomes, Artificial, Bacterial; D016296:Mutagenesis; D011995:Recombination, Genetic