Figure 2. Proposed mechanism of rhs locus rearrangement in evolved inhibitor cells.

The StLT2 rhs locus contains a full-length rhs^main gene (STM0291) and an rhs-CT^orphan gene fragment (STM0292) together with associated rhsI immunity genes. Duplication of the rhs locus would provide the opportunity for subsequent homologous recombination between the 522 bp region of near sequence identity (95%) between rhs^main and rhs-CT^orphan (depicted as diagonal hatched regions). The binding site of the Southern blot hybridization probe is indicated by the double ochre bars. Primer binding sites for PCR amplification of the rhs^main/rhs-CTorphan junction are indicated by convergent horizontal arrows.