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Figure 6 | BMC Evolutionary Biology

Figure 6

From: Evolutionary constraints permeate large metabolic networks

Figure 6

Four highly constrained reactions (P < 10-20) in cobalamin biosynthesis. a) shows the four last reactions of the cobalamin biosynthesis pathway, color-coded to help visualize their occurrence in b), which displays a 16S rDNA-based maximum-likelihood phylogenetic tree of the bacterial species analyzed here. Bars along the circumference of the tree indicate whether a specific reaction (as indicated by the bar's color) occurs in a genome or not. Bars containing two or more colors indicate that two or more reactions occur in a given species. Note that most bars contain all four colors, indicating that the respective genomes encode all three reactions. Gene symbols 'Cob*' in a) reflect names of genes known to catalyze these reactions in aerobes [36, 59]. c) shows the distance in kilobase pairs, and d) the number of genes intervening between the second and fourth reaction from a) in the studied genomes. The bimodality of this distribution is similar for the other reaction pairs (not shown).

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