Figure 5

Recombination model for the TPS system. (A) Recombination model requiring double crossover. The recipient and donor DNA are indicated in the first and the second line, respectively, and carry in the depicted example a different central core region in tpsA. IORFs are not depicted. Within the 3’ region, the tpsA genes share sequences with segments at the 5’ end of tpsC s (black boxes). The minimal recombination units (indicated by double-headed arrows) are formed by the 5’ region of a tpsC, an IORF, and the 5’ region of the immediately downstream tpsC. The recombination products show the recipient DNA organization after double crossovers with donor DNA sequences. The double-headed lines show the recombination sites where the crossovers were established. (B) Recombination model requiring an intra-chromosomal single crossover and the product of such an event evolved from the organization of the recipient DNA shown in the first line of panel A.