Cloning and characterisation of Aspergillus niger genes encoding an alpha-galactosidase and a beta-mannosidase involved in galactomannan degradation
Author
Summary, in English
α-Galactosidase (EC 3.2.1.22) and β-mannosidase (EC 3.2.1.25) participate in the hydrolysis of complex plant saccharides such as galacto(gluco)mannans. Here we report on the cloning and characterization of genes encoding an α-galactosidase (AglC) and a β-mannosidase (MndA) from Aspergillus niger. The aglC and mndA genes code for 747 and 931 amino acids, respectively, including the eukaryotic signal sequences. The predicted isoelectric points of AglC and MndA are 4.56 and 5.17, and the calculated molecular masses are 79.674 and 102.335 kDa, respectively. Both AglC and MndA contain several putative N-glycosylation sites. AglC was assigned to family 36 of the glycosyl hydrolases and MndA was assigned to family 2. The expression patterns of aglC and mndA and two other genes encoding A. nigerα-galactosidases (aglA and aglB) during cultivation on galactomannan were studied by Northern analysis. A comparison of gene expression on monosaccharides in the A. niger wild-type and a CreA mutant strain showed that the carbon catabolite repressor protein CreA has a strong influence on aglA, but not on aglB, aglC or mndA. AglC and MndA were purified from constructed overexpression strains of A. niger, and the combined action of these enzymes degraded a galactomanno-oligosaccharide into galactose and mannose. The possible roles of AglC and MndA in galactomannan hydrolysis is discussed.
Department/s
Publishing year
2001
Language
English
Pages
2982-2990
Publication/Series
European Journal of Biochemistry
Volume
268
Issue
10
Links
Document type
Journal article
Publisher
Wiley-Blackwell
Topic
- Biological Sciences
Keywords
- α-galactosidase
- expression.
- β-mannosidase
- cloning
- Aspergillus niger
Status
Published
ISBN/ISSN/Other
- ISSN: 0014-2956