Fig. 6

Diagram of homologous recombination across cob and atp6. The cob and partial cob sequences are green; the atp6 and partial atp6 sequences are grey. The conformation with all the genes located on the same DNA molecule (the joint chromosome KRA_1 and KRA_2) is depicted in the middle of the chart (a). atp6 and partial atp6 as well as cob and partial cob are in inverted orientation. Recombination across inverted repeats leads to the inversion between them; the DNA molecule is preserved. After the inversion, either the cob (top - b) or the atp6 (bottom - c) repeats become directly oriented. The recombination across them generates an independent circular molecule, the semiautonomous chromosome KRA_2 (d, e). The cob gene is located downstream of the chimeric gene bobt on the chromosome KRA_2, and it is co-transcribed with it. In contrast, the cob gene is under the control of its own promoter in two conformations of the joint chromosome