Figure 1.
The Different Module Types of Modular PKSs and Their Influence on the Structure of the Polyketide Backbone
The numbers written between domains give the typical length of the respective interdomain region in terms of amino acid residues.
ER, enoylreductase.
Figure 2.
Representative Structures of Secondary Metabolites Classes Produced by the Large PKSs of S. avermitilis
The avermectin and oligomycin structures are examples of the respective compound groups. The exact structure of the polyene macrolide compound is not known.
Figure 3.
Phylogeny of the KS Domains of Selected PKS Clusters from Streptomyces Strains
The tree was inferred by Bayesian estimation using amino acid sequences. The domains belonging to the three large PKS clusters of S. avermitilis are highlighted in red and marked by arrows. KS domains that are located outside the main oligomycin and polyene macrolide clades are labeled with a single asterisk and double asterisks, respectively.
Figure 4.
Phylogenies of the Different PKS Domain Types from S. avermitilis Projected onto the Cluster Structure
Modules that show complete congruity in all their domains are marked by asterisks on the left. The different subtypes of AT as well as KR domains are represented by different colors. The module types specified on the right are as in Figure 1.
Figure 5.
The incongruent phylogenetic clustering of the PteA2–2 AT domain is displayed in the miniaturized trees. AT–DH interdomain regions are highlighted in blue and yellow to show the hybrid character of the PteA2–2 interdomain region.
Figure 6.
Reduction Level Changes by Recombinatorial Sequence Replacements
(A) Homologous sequence stretches in the interdomain linkers of the different module types.
(B) Loss or gain of a KR domain.
(C) Exchange of a DH–KR domain unit.
(D) Creation of a mixed KR domain type by recombination. Partial amino acid sequences are depicted in blue and orange to show the hybrid character of the PteA1–2 KR domain.