Phylogenetic groupings and modular organization of ChNPS1 and ChNPS3 showing recombinant structure of these NRPSs. A. Modules 1 and 3 of both ChNPS1 and ChNPS3 group with AM toxin synthetase, a trimodular NRPS that biosynthesizes AM-toxin, an Alternaria alternata host-selective toxin. B. Module 2 of ChNPS1 and modules 2 and 4 of ChNPS3 group with A domains (SimA) of cyclosporin synthetases (CYCLO) in a disparate position in the larger phylogeny compared to modules 1 and 3 (A, above) which group in the EAS subfamily (Fig. 2). C. Recombinant domain organization of ChNPS1 and ChNPS3. Blue boxes correspond to modules 2 and 4, purple boxes to modules 1 and 3. Note that single modules homologous to these domains are found in other euascomycete NRPSs. For example, Enniatin synthetases (Esyn1) and MGG00022.6 are also recombinant like ChNPS1 and ChNPS3 with one or more modules grouping with the cyclosporin subfamily (blue boxes) and others also within the EAS subfamily but in a distinct position from the ChNPS1 and ChNPS3 modules (clear boxes). Cyclosporin synthetases itself appears to have arisen by tandem duplication of SimA modules within T. inflatum.