Construction and functional characterization of an integrative form lambda Red recombineering Escherichia coli strain.

Lambda Red recombineering is a DNA cloning and engineering technique involving recombination between homologous regions. The homologous recombination is mediated by the lambda Red genes consisting of red alpha, red beta and gam. Three lambda Red recombineering systems are currently available; the first is the plasmid-based system, in which lambda Red genes were cloned into temperature-sensitive plasmids; the second is the prophage-based system, in which lambda Red genes containing prophage were integrated into the Escherichia coli genome; the third is the integrative form system, characterized by the integration of lambda Red genes (or their counterparts) into the E. coli genome. In this study, a novel integrative form recombineering host, E. coli LS-GR, was constructed through the integration of functional recombineering elements including lambda Red genes, recA, araC and aacC1 into the E. coli DH10B genome. LS-GR shows high recombination efficiency for medium copy number vector and single copy number BAC vector modifications. The results indicate that LS-GR could be used as a general recombineering host strain.