Figure 4

Adaptive evolution analyses in GroEL of Chlamydiae. A) phylogenetic relationships between the different GroEL paralogs in Chlamydiae. The tree shows in red those branches detected to be under adaptive evolution using the maximum-likelihood free-ratio model implemented in PAML and the parsimony based approach implemented in SWAPSC. B) Three-dimensional structure of one of the Escherichia coli GroEL homo-tetradecamer protein structure (PDB accession number: 1SS8). Sites under adaptive evolution and functional divergence are highlighted as space-fill structures. Yellow, red and blue spheres label sites under adaptive evolution and/or functional divergence in the ATP binding/hydrolysis sites, sites pointing to the central cavity of the homo-tetradecamer GroEL complex and sites involved in substrate binding, respectively.