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Aspergillus niger genome-wide analysis reveals a large number of novel alpha-glucan acting enzymes with unexpected expression profiles

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Author: Yuan, X.-L. · Kaaij, R.M. van der · Hondel, C.A.M.J.J. van den · Punt, P.J. · Maarel, M.J.E.C. van der · Dijkhuizen, L. · Ram, A.F.J.
Type:article
Date:2008
Institution: TNO Kwaliteit van Leven
Source:Molecular Genetics and Genomics, 6, 279, 545-561
Identifier: 240837
doi: doi:10.1007/s00438-008-0332-7
Keywords: Biology · Alpha-amylase · Alpha-glucan · Alpha-glucosidase · AmyR · Aspergillus niger · Cell wall · Glucoamylase · Maltose · Starch · Starch-binding domain · 1,4 alpha glucan branching enzyme · alpha glucosidase · amylase · cell enzyme · cell membrane protein · fungal protein · glucan 1,4 alpha glucosidase · glycosidase · glycosylphosphatidylinositol · maltose · protein amyr · starch · article · Aspergillus niger · carbohydrate metabolism · carbon source · controlled study · degradation · energy resource · enzymatic degradation · enzyme synthesis · gene expression profiling · gene identification · gene sequence · genetic transcription · genome analysis · microarray analysis · nonhuman · nucleotide sequence · priority journal · transcription regulation · alpha-Amylase · alpha-Glucosidases · Amino Acid Sequence · Aspergillus niger · Base Sequence · Conserved Sequence · Fungal Proteins · Gene Expression Profiling · Gene Expression Regulation, Fungal · Genome, Fungal · Genomics · Glucan 1,4-alpha-Glucosidase · Glycoside Hydrolases · Maltose · Molecular Sequence Data · Phylogeny · Trans-Activators · Transcription, Genetic · Aspergillus niger · Fungi

Abstract

The filamentous ascomycete Aspergillus niger is well known for its ability to produce a large variety of enzymes for the degradation of plant polysaccharide material. A major carbon and energy source for this soil fungus is starch, which can be degraded by the concerted action of α-amylase, glucoamylase and α-glucosidase enzymes, members of the glycoside hydrolase (GH) families 13, 15 and 31, respectively. In this study we have combined analysis of the genome sequence of A. niger CBS 513.88 with microarray experiments to identify novel enzymes from these families and to predict their physiological functions. We have identified 17 previously unknown family GH13, 15 and 31 enzymes in the A. niger genome, all of which have orthologues in other aspergilli. Only two of the newly identified enzymes, a putative α-glucosidase (AgdB) and an α-amylase (AmyC), were predicted to play a role in starch degradation. The expression of the majority of the genes identified was not induced by maltose as carbon source, and not dependent on the presence of AmyR, the transcriptional regulator for starch degrading enzymes. The possible physiological functions of the other predicted family GH13, GH15 and GH31 enzymes, including intracellular enzymes and cell wall associated proteins, in alternative α-glucan modifying processes are discussed. © 2008 The Author(s).