Structure and evolution of the intergenic regions upstream of the lkt genes. Cladogram that describes bifurcation order is based on 16S rRNA phylogenies and MLEE. Greek letters indicate individual branches. The CP region (sequence shared among all Mannheimia strains) is hatched. The site of the repeat sequences in the CP region is indicated by an interruption in hatched box and the number of imperfect and perfect repeat units per promoter is indicated by red and green blocks, respectively. The ancient lapB region is presented by fountain filled box. Individual noncoding regions upstream of the CP region in M. haemolytica + M. glucosida and M. granulomatis are shown by black and white boxes, respectively. Arrows denote the putative transcription start sites. Mh, M. haemolytica: Mgl; M. glucosida; Mr, M. ruminalis; Mgr, M. granulomatis; Mv, M. varigena.