Phylogenetic analysis of the Euascomycete subclade. Tree extracted from the maximum likelihood (PhyML with WAG plus gamma substitution matrix) phylogeny of the complete A domain dataset (Additional file 6B). Branches defining subgroups of the EAS clade grouping with a C. heterostrophus NRPS A domain or with A domains from fungal NRPSs with known function are color coded: dark blue = peptaibol synthetases, light blue = ChNPS4 (clades grouping with each A domain of C. heterostrophus NPS4), green = AMT synthetases and ChNPS1 and ChNPS3 modules 1 and 3, orange = ergot alkaloid synthetases, light green = ChNPS8/PerA synthetases, and red = homologs of ChNPS6 (extracellular siderophore synthetases). Of these groups, only the peptaibol synthetases, the clade containing NPS8/PerA/NPS6 synthetases (arrow), and ChNPS4 modules 3 and 4 have bootstrap support >70%. C. heterostrophus NRPS A domains are indicated (circles).