Scheme of a construction of multiple chromosomal modifications, using the combined λ Red-Int/Xis system. A) Selective marker M flanked by attLλ/attRλ is used for introduction of an appropriate mutation into the chromosome by λ Red-dependent recombination. Then the marker is eliminated from the chromosome by λ Int/Xis site-specific recombination. As a result, only the 31 bp long attBλ sequence linked to the mutation remains in the chromosome. Selective marker M can then be used in the next step of the introduction of multiple chromosomal modifications. B) The sequence of the attBλ site. One of the six ORFs provided by this sequence does not contain stop codons. Hence, it is possible to design an "in-frame" deletion of a gene. Asterisks mark stop codons.
Katashkina et al. BMC Molecular Biology 2009 10:34 doi:10.1186/1471-2199-10-34