Characterisation of the Aspergillus niger dapB gene, which encodes a novel fungal type IV dipeptidyl aminopeptidase.
We have cloned the Aspergillus niger dapB gene. Analysis of its nucleotide sequence and the corresponding protein sequence indicates that the gene encodes a type IV dipeptidyl aminopeptidase (DPP IV). Based upon its deduced sequence we predict the presence of a transmembrane domain in the protein. Furthermore, dapB-overexpressing transformants display an increase in intracellular DPP IV activity. This is the first reported characterisation of a dipeptidyl aminopeptidase with a transmembrane domain from a filamentous fungus. Using the dapB sequence as a query, we were able to identify 14 DPP IV-encoding genes, and 12 additional DPPIV proteases in public genomic databases. Phylogenetic analysis reveals that in yeasts there are two clades of genes that encode DPP IV proteases with a transmembrane domain. In this study we demonstrate that, as in yeasts, two classes of DPP IV-encoding genes exist in filamentous fungi. However, only one of these codes for DPP IV proteases with a transmembrane domain. The second type present in filamentous fungi encodes extracellular DPP IV proteases. The dapB gene belongs to the first cluster. We propose that DapB plays a role in the proteolytic maturation of enzymes produced by A. niger.
Jalving
Ruud
R
Laboratory of Microbiology, Section Fungal Genomics, Wageningen University and Research Centre, Dreijenlaan 2, 6703 HA, Wageningen, The Netherlands.
Godefrooij
Jeroen
J
Veen
Wim J Ter
WJ
van Ooyen
Albert J J
AJ
Schaap
Peter J
PJ
D001234:Aspergillus niger / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D016000:Cluster Analysis; D019295:Computational Biology; D017931:DNA Primers; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D005800:Genes, Fungal / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA
D017931:DNA Primers; D008565:Membrane Proteins; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases