Figure 1

Comparative analysis of S. coelicolor M145 – S. lividans TK21 chromosomes and genomic features in S. coelicolor. ( a ) Log₂ hybridization ratio as a function of S. coelicolor ORFs. Low values imply absence or divergence of gene in S. lividans. Experimental data (blue circles) and smoothened data using median of a 19-gene sliding window (thick line) are shown. Large genomic islands (red), smaller islets (orange) and S. coelicolor specific chromosome end regions (green) identified in this study are marked with filled bars. The sizes of the bars approximate the extent of each island. GI and Gi numbers corresponding to those in Table 1 are indicated. Note that the smoothened curve, shown here for ease of visualization, will not show a dip in hybridization ratios for genomic islets with fewer than 10 genes. ( b ) Logarithm of codon adaptation index (CAI) as a function of S. coelicolor ORFs. Low log₂ CAI implies sub-optimal codon usage. ( c ) z' value plotted as a function of distance from chromosome left end. A sharp increase in z' value indicates presence of an AT-rich region. The figure shows that there exists a good correlation between presence of genomic islands, codon usage bias and local GC content.