Figure 7

AT content bias in rbcL and complete carboxysomal operon sequences in Paulinella and Prochlorococcus. Whereas the AT-content in codon positions 1 + 2 in the rbcL gene is balanced across Paulinella and 17 free-living α-cyanobacteria (A), the third codon position displays a sharply elevated AT-content in Paulinella as well as Prochlorococcus strains (B). The AT-content integrated over the complete carboxysomal operon (from csoS1 to pepB) including intergenic spacer regions shows a similar bias, although less pronounced (C).