Chromosome rearrangements generating the transition between the two Bifidobacterium longum configurations. Maps of B. longum NCC2705 in configurations I (A), II (B) and the proposed mechanism mediating the transition between the two configurations (C). Segments a, b, c and d are indicated. Gene dnaA and the integrated plasmid are represented by an arrow and a thin black line, respectively. ISBlo2a and b are indicated by open triangles, ISBLo5c and d by solid ones. For each segment, thick black arrows indicate the orientation of transcription of the majority of the genes.