Aspergillus niger genome-wide analysis reveals a large number of novel alpha-glucan acting enzymes with unexpected expression profiles.
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 alpha-amylase, glucoamylase and alpha-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 alpha-glucosidase (AgdB) and an alpha-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 alpha-glucan modifying processes are discussed.
Yuan
Xiao-Lian
XL
Clusius Laboratory, Molecular Microbiology and Kluyver Centre for Genomics of Industrial Fermentations, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands. xyuan@science.uva.nl
van der Kaaij
Rachel M
RM
van den Hondel
Cees A M J J
CA
Punt
Peter J
PJ
van der Maarel
Marc J E C
MJ
Dijkhuizen
Lubbert
L
Ram
Arthur F J
AF
D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000378:metabolism; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D016681:Genome, Fungal; D023281:Genomics; D005087:Glucan 1,4-alpha-Glucosidase / Q000145:classification / Q000235:genetics / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000235:genetics*; D008320:Maltose / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic; D000516:alpha-Amylases / Q000145:classification / Q000235:genetics / Q000378:metabolism; D000520:alpha-Glucosidases / Q000145:classification / Q000235:genetics / Q000378:metabolism
D005656:Fungal Proteins; D015534:Trans-Activators; C414005:amyR protein, Aspergillus; D008320:Maltose; D006026:Glycoside Hydrolases; D000516:alpha-Amylases; D000520:alpha-Glucosidases; D005087:Glucan 1,4-alpha-Glucosidase