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Characterization of A spergillus nidulans α‐glucan synthesis: roles for two synthases and two amylases
Author(s) -
He Xiaoxiao,
Li Shengnan,
Kaminskyj Susan G. W.
Publication year - 2014
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12480
Subject(s) - aspergillus nidulans , biology , conidiation , glucan , echinocandins , cell wall , biochemistry , microbiology and biotechnology , gene , virulence , mutant , antifungal , amphotericin b , caspofungin
Summary Cell walls are essential for fungal survival and growth. Fungal walls are ∼ 90% carbohydrate, mostly types not found in humans, making them promising targets for anti‐fungal drug development. Echinocandins, which inhibit the essential β‐glucan synthase, are already clinically available. In contrast, α‐glucan, another abundant fungal cell wall component has attracted relatively little research attention because it is not essential for most fungi. A spergillus nidulans has two α‐glucan synthases ( AgsA and AgsB ) and two α‐amylases ( AmyD and AmyG ), all of which affect α‐glucan synthesis. Gene deletion showed that AgsB was the major synthase. In addition, AmyG promoted α‐glucan synthesis whereas AmyD had a repressive effect. The lack of α‐glucan had no phenotypic impact on solid medium, but reduced conidial adhesion during germination in shaken liquid. Moreover, α‐glucan level correlated with resistance to C alcofluor W hite. Intriguingly, overexpression of agsA could compensate for the loss of agsB at the α‐glucan level, but not for phenotypic defects. Thus, products of AgsA and AgsB have different roles in the cell wall, consistent with agsA being mainly expressed at conidiation. These results suggest that α‐glucan contributes to drug sensitivity and conidia adhesion in A . nidulans , and is differentially regulated by two synthases and two amylases.