Co-evolution of the tuf genes links gene conversion with the generation of chromosomal inversions.

The tufA and tufB genes in Salmonella typhimurium co-evolve by recombination and exchange of genetic material. A model is presented which predicts that co-evolution is achieved by gene conversions and chromosomal inversions. Analysis of recombinants reveals that conversion and inversion each occur with similar rates and each depends on RecBCD activity. The model predicts sequence structures for different classes of post-recombination tuf genes. Sequence analysis reveals the presence of each of these structures and classes, with a predicted bias in the absence of mismatch repair. An implication of these data is that co-evolution of gene families can be linked with the generation of chromosomal rearrangements.