Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/22/2015
Publication Date: 3/22/2015
Citation: Brown, D.W., Ward, T.J., Proctor, R. 2015. Lessons from 455 Fusarium polyketide synthases [abstract].
Technical Abstract: In fungi, polyketide synthases (PKSs) synthesize a structurally diverse array of secondary metabolites (SMs) with a range of biological activities. The most studied SMs are toxic to animals and/or plants, alter plant growth, have beneficial pharmaceutical activities, and/or are brightly colored pigments. Here, examination of genome sequence data from 30 species of Fusarium identified 455 ostensibly functional PKS genes and 85 nonfunctional PKS pseudogenes. In phylogenetic analyses, the functional PKS genes were resolved into the four clades previously described for Type I fungal PKSs. Only three PKSs were present in all 30 species, and although more closely related species tended to share more closely related PKS gene homologs, there is marked variation in the presence and absence of the homologs among closely related species. For example, the PKS required for depudecin synthesis is present in five members of the Fusarium fujikuroi species complex that were examined, but absent in the seven other members of this complex. In contrast, 12 PKS genes were unique to one or two of the species examined. These findings suggest frequent independent loss of PKS genes within species complexes (multispecies lineages) of Fusarium as well as horizontal transfer of multiple PKS genes between Fusarium species. Overall, based on the predicted functional domain content of each of the PKSs as well as their phylogenetic relationships to one another and to other fungal PKSs, we propose that the 455 Fusarium PKSs constitute at least 51 distinct functional orthologs that have the potential to synthesize structurally distinct polyketides.