ABSTRACT: Development of Monacolin K Hyper-Producing Mutants by Synchrotron Light-induced mutation in Monascus purpureus and Their Comparative Genome Analysis
Project description:M. purpureus YY-1 is widely used in food colorant production in China. In our previous study, the whole-genome information of YY-1 was clearly illustrated, which provided useful hints for evolution esearch and industrial applications. However, the presence of citrinin, which has nephrotoxic, hepatotoxic, and carcinogenic activities, attracts people′s attention to the safety of Monascus products. In order to reduce the harm of citrinin in Monascus related products, in this study, a random mutant of M. purpureus YY-1, with scarce citrinin production (designated as winter) was obtained. To analyze the biosynthesis and regulation mechanism of pigment and citrinin, transcriptomic analysis of M. purpureus YY-1 and winter was performed. Comparative transcriptomic analysis reveals pksCT, the essential gene for citrinin synthesis, showed low expression level in M. purpureus YY-1 and winter, which suggested there might be isoenzymes in M. purpureus YY-1 that were responsible for the citrinin synthesis during evolution. In addition, the expression change of transcription factors may also influence the regulatory network of citrinin synthesis pathway of in M. purpureus. Moreover, the yields of pigments produced by the winter mutant were significantly increased. Repressing central carbon metabolism and improving the acetyl-CoA pool can contribute to the high yield of pigments, and enhanced NADPH regeneration also lead the metabolic flux to pigments in M. purpureus. Investigations on biosynthesis and regulation of citrinin and pigment production in M purpureus will enhance our knowledge of the mechanisms in fungal secondary metabolite biosynthesis.
Project description:In eukaryotes, Methylation of histone H3 at lysine 4 (H3K4me) catalyzed by the complex of proteins associated with Set1 (COMPASS) complex, is crucial for gene transcriptional regulation and organisms’ development. In Monascus, the COMPASS complex subunits Ccla and Swd1 affected the growth and development, and secondary metabolites synthesis. However, the functions of COMPASS core subunits Set1 and Swd3, as well as the establishment of methylation of histone H3 at lysine 4 (H3K4me) are still unclear. In this study, we identified the conserved subunits MpSet1 and MpSwd3 in Monascus purpureus and found that MpSet1 and MpSwd3 were required for the establishment of H3K4me. Loss of MpSet1 and MpSwd3 resulted in slower growth and development, inhibited formation of cleistothecia, ascospores and conidia, and reduced Monascus pigments (MPs) synthesis. In addition, high-throughput sequencing (RNA-seq) and qRT-PCR showed that loss of MpSet1 and MpSwd3 resulted in differential transcriptional alteration of 2646 and 2659 genes, respectively, and the transcriptions of MPs synthesis related genes (MSGs) were repressed. These results indicated that MpSet1 and MpSwd3 are crucial for the growth and development, spore formation and MPs synthesis, and MpSet1 and MpSwd3 were necessary for the establishment of H3K4me and activated MSGs transcriptions to regulate MPs synthesis. In addition, MpSet1 and MpSwd3 responded to cell wall stress by activating genes encoded for chitin synthases, so that maintaining the integrity of cell wall.
