Identification and Heterologous Reconstitution of a Polyketide Synthase from the Endophytic Strain Shiraia SP. Lfs18
A type III polyketide synthase gene (Sl-ars) was discovered from the genome of Shiraia sp. Lfs18, an endophytic fungal strain from Huperzia serrata. The intron-free gene was cloned from the cDNA and ligated respectively to two shuttle vectors pET28a and YEpADH2p-URA3 for expression in Escherichia coli BL21(DE3) and Saccharomyces cerevisiaeBJ5464-NpgA. Sl-ARS was efficiently expressed in E. coli BL21(DE3), leading to the synthesis of a series of polyketide products. Six major products were isolated and characterized as 5-alk(en)ylresorcinol with various fatty acyl side chains. Addition of IPTG at different OD600 values influenced the yields of these products. Expression of Sl-ARS in the yeast also lead to the synthesis of several 5-alk(en)ylresorcinol.
Key words - Polyketide synthase, alkylresorcinols, Escherichia coli, Saccharomyces cerevisiae