Metabolic Reprogramming Driven by mpSte11A Deletion Redirects Carbon Flux toward Overproduction of Monascus Pigments in Monascus spp

Monascus spp., a food fermentation microorganism, produced valuable secondary metabolites including Monascus pigments (MPs) which served as natural food colorants. However, rational metabolic engineering to enhance MPs production remained limited by the lack of regulatory targets that govern metabolic branching. Mitogen-activated protein kinase cascades, particularly the STE20-STE11-STE7 core module, regulated fungal growth and metabolism, but their roles in MPs biosynthesis remain unexplored. In this study, we functionally characterized MpSte11A, the first STE11 homolog identified in Monascus spp., through bioinformatic analysis and genetic manipulation. Most importantly, deletion of mpSte11A triggered a profound metabolic shift, which resulted in a 22-fold increase in MPs production. Integrated transcriptomic and metabolomic analysis revealed that MpSte11A functioned as a metabolic gatekeeper where its deletion redirected carbon flux from primary to MPs biosynthesis by controlling the TCA cycle. These findings not only elucidated the signaling role of the MAPK cascade in Monascus spp. specialized metabolism but also provided a robust strategy for re-engineering carbon partitioning to maximize the output of high-value secondary metabolites in filamentous fungal cell factories. ImportanceFilamentous fungi are versatile cell factories for the production of diverse high-value secondary metabolites, but the rational enhancement of these compounds is often limited by a lack of universal regulatory targets. In this study, we employed the food-fermentation fungus Monascus spp. as a model and identified MpSte11A as a master "metabolic gatekeeper" that governed the trade-off between fungal growth and secondary metabolism. By disrupting this single signaling node, we achieved a remarkable 22-fold increase in compound production. This significant enhancement resulted from a systematic redirection of carbon flux from primary growth (the TCA cycle) to secondary biosynthesis. This work provided a precise molecular blueprint for the reprogramming of fungal metabolism. It also demonstrated that the tuning of core MAPK modules is a powerful and broadly applicable strategy for the engineering of robust fungal cell factories producing a wide array of bioproducts. Graphical Abstract (For Table of Contents Only) O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/703344v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1b062a5org.highwire.dtl.DTLVardef@11c4cd6org.highwire.dtl.DTLVardef@f8a34eorg.highwire.dtl.DTLVardef@1a97f69_HPS_FORMAT_FIGEXP M_FIG C_FIG