Figure 1

Schematic representation of integration of a reporter construct after a single crossover event using the pyrG* targeting system. This system was described previously by van Gorcom and van den Hondel [9]. Strain AB4.1 contains a base deletion at position 378 in the pyrG open reading frame indicated with a *. A circular plasmid containing the reporter gene and the mutated pyrG gene (pyrG ^BamHI) is transformed to AB4.1 and a single cross over at the pyrG locus leads to integration into the genome. Note that the entire vector is integrated in this system. The pyrG* fragment is a located on a 3.8 kb XbaI subclone and can be inserted in a vector for targeted integration.