Strategies for measuring DNA recombination. (A) Truncated tetA genes. Two truncated tetA genes were derived from an intact tetA gene and its promoter (P). 5'tet, includes the tetA promoter and the 5' portion of tetA gene. 3'tet, consists of the 3' portion of the tetA gene. The overlapping region (between 5'tet and 3'tet) varies from 466 to 789 bp depending on the system. Homologous recombination can occur between the two truncated tetA genes at the overlapping region, leading to the formation of a functional tetA gene. (B) Intermolecular recombination. Each DNA molecule carries either 5'tet or 3'tet. A single crossover between the two molecules occurs at the regions of homology, and leads to a functional tetA gene. (C) Intramolecular recombination. The two truncated tetA genes were placed on one molecule in the same orientation. A single crossover between the regions of homology leads to a functional tetA gene.
Zhang et al. BMC Microbiology 2011 11:31 doi:10.1186/1471-2180-11-31