A possible role of the key enzymes of the glyoxylate and gluconeogenesis pathways for fruit-body formation of the wood-rotting basidiomycete Flammulina velutipes

Abstract

Biochemical roles of the representative enzymes involved in carbon metabolism of glucose were investigated in relation to the fruit-body formation of the basidiomycete Flammulina velutipes. Changes in specific activities of the enzymes of the tricarboxylic acid (TCA) cycle and glyoxylate (GLOX) and gluconeogenesis pathways were measured at different stages of development of the fungus. The enzyme activities of malate synthase (MS) and fructose bisphosphatase (FBP) as the key enzymes for the GLOX-gluconeogenesis pathways increased in mycelia during the fruit-body formation. The activities of isocitrate dehydrogenase (IDH) for the TCA cycle and NADP-linked glutamate dehydrogenase (GLTDH (NADP)) for glutamate synthesis increased more markedly. Moreover, the mycelial mat of the cultures producing fruit bodies yielded greater enzyme activities of isocitrate lyase (ICL), MS, FBP, and IDH than that of the cultures that did not produce fruit bodies. These results suggest that the GLOX-gluconeogenesis pathways as well as the glutamate synthesis have a strong correlation with the fruit-body formation of F. velutipes.