CO2 control of fruiting in Schizophyllum commune: noninvolvement of sustained isocitrate lyase derepression

Abstract

The activity of the enzyme, isocitrate lyase, was repressed in glucose cultures of Schizophyllum commune and derepressed in acetate-grown mycelium of this basidiomycetous fungus. The maximum acetate-derepressed level of this soluble enzyme was comparable in individual homokaryotic mycelium or in the dikaryon. Addition of CO₂, NaHCO₃, or CaCO₃ did not significantly derepress isocitrate lyase activity in glucose-cultures. Neither normal dikaryotic fruiting nor its inhibition by carbon dioxide resulted in marked and sustained changes in isocitrate lyase. Thus, a fluctuation in isocitrate lyase activity does not appear to be the salient response of S. commune to increased CO₂ tension.