Mitochondrial pyruvate carrier influences ganoderic acid biosynthesis in Ganoderma lucidum

Area of Science:

• Biochemistry
• Molecular Biology
• Mycology

Background:

• Mitochondrial pyruvate carriers (MPCs) are crucial for pyruvate transport into mitochondria, regulating key metabolic pathways.
• The metabolic roles of MPCs in macrofungi, particularly in secondary metabolite biosynthesis, remain largely unexplored.
• Ganoderma lucidum produces ganoderic acids (GAs), valuable bioactive compounds, whose biosynthesis is influenced by cellular metabolism.

Purpose of the Study:

• To investigate the function of Mitochondrial Pyruvate Carriers (MPCs) in Ganoderma lucidum (GlMPC) concerning ganoderic acid (GA) biosynthesis.
• To elucidate the regulatory role of GlMPCs in pyruvate distribution and its impact on metabolic pathways like the TCA cycle and fatty acid metabolism.

Main Methods:

• Gene silencing of GlMPC1 and GlMPC2 in Ganoderma lucidum to create transformants.
• Quantification of pyruvate distribution between mitochondria and cytoplasm.
• Measurement of ganoderic acid (GA) content.
• Assay of key enzyme activities and expression levels in the TCA cycle and fatty acid β-oxidation (FAO).

Main Results:

• Silencing GlMPCs significantly reduced mitochondrial pyruvate levels and increased GA content by approximately 50%.
• TCA cycle rate was not significantly downregulated; isocitrate dehydrogenase (IDH) activity increased by 44% in silenced transformants.
• Co-silencing of GlMPCs with FAO-related genes led to a 40% reduction in GA content, indicating FAO's role in GA biosynthesis.

Conclusions:

• GlMPCs play a critical role in regulating pyruvate distribution between the mitochondria and cytoplasm in Ganoderma lucidum.
• Acetyl-CoA derived from fatty acid β-oxidation (FAO) is essential for maintaining the TCA cycle and promoting GA accumulation.
• Targeting GlMPCs and understanding the interplay between pyruvate metabolism, FAO, and the TCA cycle offers potential strategies for enhancing GA production.