Abstract
The AMP-activated protein kinase (AMPK)/Sucrose-nonfermenting serine-threonine protein kinase 1 (Snf1) plays an important role in metabolic remodelling in response to energy stress. However, the role of AMPK/Snf1 in responding to other environmental stresses and metabolic remodelling in microorganisms was unclear. Heat stress (HS), which is one important environmental factor, could induce the production of reactive oxygen species and the accumulation of ganoderic acids (GAs) in Ganoderma lucidum. Here, the functions of AMPK/Snf1 were analysed under HS condition in G. lucidum. We observed that Glsnf1 was rapidly and strongly activated when G. lucidum was exposed to HS. HS significantly increased intracellular H2O2 levels (by approximately 1.6-fold) and decreased the dry weight of G. lucidum (by approximately 45.6%). The exogenous addition of N-acetyl-l-cysteine (NAC) and ascorbic acid (VC), which function as ROS scavengers, partially inhibited the HS-mediated reduction in biomass. Adding the AMPK/Snf1 inhibitor compound C (20 μM) under HS conditions increased the H2O2 content (by approximately 2.3-fold of that found in the strain without HS treatment and 1.5-fold of that found in the strain under HS treatment without compound C) and decreased the dry weight of G. lucidum (an approximately 28.5% decrease compared with that of the strain under HS conditions without compound C). Similar results were obtained by silencing the Glsnf1 gene. Further study found that Glsnf1 meditated metabolite distribution from respiration to glycolysis, which is considered a protective mechanism against oxidative stress. In addition, Glsnf1 negatively regulated the biosynthesis of GA by removing ROS. In conclusion, our results suggest that Glsnf1-mediated metabolic remodelling is involved in heat stress adaptability and the biosynthesis of secondary metabolites in G. lucidum.