Role of a Cell-Wall Glucan-degrading Enzyme in Mating of Schizophyllum commune

Abstract

Mycelial enzyme extracts of Schizophyllum commune were prepared during vegetative growth matings leading to common- A and common- B heterokaryons and the dikaryon, and were examined for hydrolytic activity against an alkaliinsoluble cell-wall glucan (R-glucan) isolated from this mushroom. In extracts from several individual homokaryotic mycelia the R-glucanase activity was low and did not increase when the cultures exhausted glucose in the medium. In common- A matings, a 30-fold increase in specific activity of intracellular R-glucanase was found even in the presence of glucose in the broth. An increase of this magnitude was not observed in the common- B mating nor in the fully compatible cross leading to the dikaryon. Extracts of the dikaryon did show elevated R-glucanase activity after exogenous glucose disappearance and subsequent fruiting. In none of these situations was an enzyme activity detected towards an alkali-soluble cell-wall glucan (S-glucan) prepared from S. commune . Changes in R-glucanase were not parallelled by identical changes in laminarinase, pustulanase, cellobiase, and p -nitrophenyl-β- d -glucosidase, but comparable increases in specific activities were found for hydrolysis of glycogen and maltose. After interaction of the various mycelia in mating combinations, the S-glucan/R-glucan ratio of the cell wall of the dikaryon was found to be similar to that of the homokaryons, but increased in the common- B interaction and was elevated almost threefold in the common- A heterokaryon.