Biochemical Studies on the Thermal Dimorphism of Paracoccidioides brasiliensis1

AUTOR(ES)

Kanetsuna, Fuminori

RESUMO

The biochemical and morphological changes of the yeastlike (Y) form to the mycelial (M) form of Paracoccidioides brasiliensis were examined. The main polysaccharide of hexoses of the Y-form cell wall was α-glucan, whereas the polysaccharides of the M-form cell wall were β-glucan and galactomannan. The α-glucan of the Y form contained mainly α-(1 → 3)-glycosidic linkage. The β-glucan of the M form contained mainly β-(1 → 3)-glycosidic linkage with a few branches at C-6 position. The incorporation of 14C-glucose into the cell wall glucans showed that synthesis of α-glucan decreased rapidly after the temperature of the culture was changed from 37 to 20 C. The synthesis of β-glucan was augmented at an early stage of the morphological change. The M-form cell wall contained 12 times more disulfide linkage than the Y form. The cell-free extracts of the whole cell of the Y form had five times more protein disulfide reductase activity than the M form, whereas extracts of the M form contained five to eight times more β-glucanase activity than the Y form. From these results, a hypothesis for the production of the M form from the Y form is proposed.

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