Figure 8.1.
Modular organization of type I polyketide synthases (PKSs). (A) A prototypical type I PKS module contains the cognate ATdomain and other domains. (B) An AT-less type I PKS module lacks the cognate AT domain but often contains a short segment of remnant AT residues. (C) The remnant ATsegment lacks critical catalytic motifs (GHSxG and AFHS) and is therefore catalytically inactive, but may serve as a docking domain mediating the interactions between the discrete AT (LnmG) and AT-less PKS modules in LnmI and LnmJ (Tang et al., 2004).