Chalcone synthases (CHSs) are prominent members of type III polyketide synthase (PKS) superfamily, and are known to play a vital role in the biosynthesis of plant phenylpropanoids and flavonoids. By virtue of their agricultural and pharmaceutical values, products of type III PKSs have received significant attention in recent years. Although the distribution of type III PKSs has always been considered to be restricted to either plants or bacteria, the present study reveals the existence of type III PKS-encoding genes in an industrially useful fungus, Aspergillus oryzae. While A. oryzae genome data mining revealed 4 putative CHS-like sequences (csyA, csyB, csyC and csyD), reverse transcription polymerase chain reaction indicated the expression of 3 genes (csyA, csyB and csyD). In addition, we confirmed the presence of type III PKS-encoding genes in other filamentous fungi by using the available fungal genome databases. Phylogenic analysis revealed the distinction of fungal type III PKSs from those of bacteria and plants. Interestingly, the other species of Aspergilli (Aspergillus nidulans, Aspergillus fumigatus) lacked these genes. Significantly, A. oryzae alone contained higher number of putative chalcone synthase homologues in comparison to Neurospora crassa (1), Fusarium graminearum (1), Magnaporthe grisea (2) and Phanerochaete chrysosporium (3). Disruption of these novel PKS genes in A. oryzae is being pursued to elucidate their function in A.oryzae.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)