Regulation of beta-1,3-glucanase synthesis in Penicillium italicum

Abstract

The filamentous fungus P. italicum produced a certain level of .beta.-1,3-glucanase during active growth in a glucose-supplemented medium; at a low glucose concentration (2-10 mM), derepression took place and the specific activity of the enzyme increased significantly. Derepressed cells (incubated in a glucose-limited medium) accumulated a capacity for the synthesis of .beta.-1,3-glucanase, which led to a subsequent increase in the specific activity even when the cells were transferred to a medium with an excess of glucose (180 mM). Two protein synthesis inhibitors, cycloheximide and trichodermin, immediately stopped the increase in specific activity when added to derepressed cells. 8-Hydroxyquinoline, an RNA synthesis inhibitor, acted differently, since it permitted the specific activity to increase for some time after being added to derepressed cells. The concentration of glucose did not affect the 8-hydroxyquinoline-insensitive synthesis of .beta.-1,3-glucanase. The glucose repression effect on .beta.-1,3-glucanase production must be exerted at a pretranslation level that could be mRNA synthesis or some stage of the process involved in its maturation or stabilization.