Heterologous Expression Of Fugnal Polyketide Synthases6-MSAS, MOS And PksCT In Pichia Pastoris

Polyketides are a diverse class of secondary metabolites with great biological and pharmacological activities. Heterologous expression of polyketide synthase (PKS) is a potential approach to improve the production of polyketide. In this study, we aimed to develop a yeast platform based on Pichia pastoris for heterologous expression of polyketide.When npgA from Aspergillus nidulans was expressed in P. pastoris, a sensitive fluorescent assay was performed to determine its phosphopantetheinylation function of4’-Phosphopantetheine transferase (PPTase). The fluorescence of citrinin polyketide synthase (pksCT) acyl carrier protein (ACP) domain in crude protein showed the the ACP domain was phosphopantetheinylated successfully by NpgA. In this work, we coexpressed the PPTase from A. nidulans with atX gene from A. terrus which expressed6-methylsalicylic acid synthase (6-MSAS), Tspksl gene from Talaromyces stipitatus which expressed3-methylorcinaldehyde synthase (MOS) and pksCT gene from Monascus purpureus which expressed pksCT in P. pastoris GS115, respectively. Coexpression of atX with npgA led to the production of the desired polyketide6-methylsalicylic acid (6-MSA). After67h fermentation in5L-scaled, wet cells weight of the recombinant P. pastoris Mut+strain reached to238g/L, and the concentration of6-MSA was2.2g/L. However, there was no specific compound obtained by coexpression of Tspksl or pksCT with NpgA. The reason might to be discussed further.