Isomaltose formed by α-glucosidases triggers amylase induction in Aspergillus nidulans
- 314 Downloads
Among various α-glucobioses examined, isomaltose was the most effective inducer for amylase synthesis in Aspergillus nidulans. Amylase induction by maltose was completely inhibited by addition of cast-anospermine or cycloheximide, while induction by isomaltose was not affected by the inhibitors, suggesting that amylase induction by maltose requires inducible α-glucosidases. Disruption of the α-glucosidase A gene (agdA), the α-glucosidase B gene (agdB), or both genes did not abolish maltose-dependent induction, although amylase production induced by maltose decreased about 2-fold in the agdA/agdB double disruptant, compared with that in the agdB disruptant at all concentrations tested. Upon induction by isomaltose, amylase synthesis was enhanced considerably in the agdB and agdA/agdB disruptants. Even at 3 nM, isomaltose induced amylase production in the double disruptant, supporting the suggestion that isomaltose is a physiological inducer for amylase. Therefore, maltose must be converted to isomaltose by α-glucosidases prior to triggering amylase synthesis, but no specific α-glucosidase is required for amylase induction by maltose. Probably any α-glucosidases having isomaltqse-forming activity, including AgdA and AgdB, may participate in amylase induction by maltose.
KeywordsAspergillus nidulans α-Glucosidase Isomaltose Amylase induction
Unable to display preview. Download preview PDF.
- Chiba S (1988) α-Glucosidases. In: Amylase Research Society of Japan (ed) Handbook of amylases and related enzymes. Pergamon, Oxford, pp 104–105Google Scholar
- Flipphi M, Mathieu M, Cirpus I, Panozzo C, Felenbok B (2001) Regulation of the aldehyde dehydrogenase gene (aldA) and its role in the control of the coinducer level necessary for induction of the ethanol utilization pathway in Aspergillus nidulans. J Biol Chem 276:6950–6958PubMedCrossRefGoogle Scholar
- Kita A, Matsui H, Somoto A, Kimura A, Takata M, Chiba S (1991) Substrate specificity and subsite affinities of crystalline α-glucosidase from Aspergillus niger. Agric Biol Chem 55:2327–2335Google Scholar
- Nelson N (1944) A photometric adaptation of the Somogyi method for the determination of glucose. J Biol Chem 153:375–380Google Scholar
- Tonomura K, Suzuki H, Nakamura N, Kuraya K, Tanabe O (1961) On the inducers of α-amylase formation in Aspergillus oryzae. Agric Biol Chem 25:1–6Google Scholar