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The effect of tunicamycin on secreted glycosidases of Aspergillus niger

1981; Elsevier BV; Volume: 210; Issue: 1 Linguagem: Inglês

10.1016/0003-9861(81)90170-3

1096-0384

Brian K. Speake, David J. Malley, F. W. Hemming,

Biofuel production and bioconversion

The main glycosidases secreted into the culture medium during growth of Aspergillus niger were β-glucosidase, α-galactosidase, and β-N-acetylglucosaminidase. In the presence of tunicamycin, an inhibitor of protein N-glycosylation, the activities of these enzymes in the culture medium were considerably decreased, whereas fungal growth and total mycelial protein content were not diminished. Intracellular glycosidase activity was also reduced in the presence of tunicamycin. The antibiotic also caused a decrease in the incorporation of mannose into total protein of the culture filtrate. Polyacrylamide gel electrophoresis of these proteins indicated that the majority of the mannosylated proteins were affected. The incorporation of leucine into total culture filtrate protein was not inhibited by tunicamycin. The amount of β-N-acetylglucosaminidase in the culture medium was estimated by immunotitration of enzyme activity with specific antiserum. The results suggest that the decreased enzyme activity observed during growth in the presence of tunicamycin is due to a reduced amount of enzyme.