Seminar: Phylogenomic Study of Iterative Polyketide Synthase Genes in Aspergillus Species

Speaker: Dr. Shu-Hsi Lin (Center for Food and Biomolecules of National Taiwan University, Taipei, Taiwan)

Date & Time: Tuesday, July 23, 2:00pm – 3:00pm

Venue: Seminar room C016 (Lab1, Level C)

Title: Phylogenomic Study of Iterative Polyketide Synthase Genes in Aspergillus Species

Genome mining efforts have revealed the presence of a large number of genes related to secondary metabolism in Aspergillus. Among them, polyketide synthases (PKS) are particularly abundant as a gold mine for bioactive compounds. In this study, we not only created a wiki-based database for polyketide data collection, but also used a phylogenomic approach to investigate the distribution of iterative PKS in eight sequenced Aspergilli and classified over 250 fungal genes. Their genealogy by the conserved ketosynthase (KS) domain revealed three large groups of nonreducing PKS, one group inside bacterial PKS, and more than 9 small groups of reducing PKS. Polyphyly of nonribosomal peptide synthase (NRPS)-PKS genes raised questions regarding the recruitment of the elegant conjugation machinery. High rates of gene duplication and divergence were frequent. This study and our database have paved a way of predicting of possible polyketide chemotypes and redesigning the novel polyketide biosynthesis by the modification of the synthase architecture. In summary, KS phylogeny provides ideas to assess the diversity of secondary metabolites and to identify new uncharacterized PKS classes. The PKS wiki-database will further integrate various types of polyketide information and facilitate the identification and the application of new bioactive products. All data are accessible through our web database at http://metabolomics.jp/wiki/Category:PK.