Sedolisins, a new class of secreted proteases from Aspergillus fumigatus with endoprotease or tripeptidyl-peptidase activity at acidic pHs.
The secreted proteolytic activity of Aspergillus fumigatus is of potential importance as a virulence factor and in the industrial hydrolysis of protein sources. The A. fumigatus genome contains sequences that could encode a five-member gene family that produces proteases in the sedolisin family (MEROPS S53). Four putative secreted sedolisins with a predicted 17- to 20-amino-acid signal sequence were identified and termed SedA to SedD. SedA produced heterologously in Pichia pastoris was an acidic endoprotease. Heterologously produced SedB, SedC, and SedD were tripeptidyl-peptidases (TPP) with a common specificity for tripeptide-p-nitroanilide substrates at acidic pHs. Purified SedB hydrolyzed the peptide Ala-Pro-Gly-Asp-Arg-Ile-Tyr-Val-His-Pro-Phe to Arg-Pro-Gly, Asp-Arg-Ile, and Tyr-Val-His-Pro-Phe, thereby confirming TPP activity of the enzyme. SedB, SedC, and SedD were detected by Western blotting in culture supernatants of A. fumigatus grown in a medium containing hemoglobin as the sole nitrogen source. A degradation product of SedA also was observed. A search for genes encoding sedolisin homologues in other fungal genomes indicates that sedolisin gene families are widespread among filamentous ascomycetes.
Reichard
Utz
U
Department of Medical Microbiology, University Hospital of Göttingen, Kreuzbergring 57, D-37075 Göttingen, Germany. ureicha@gwdg.de
Léchenne
Barbara
B
Asif
Abdul R
AR
Streit
Frank
F
Grouzmann
Eric
E
Jousson
Olivier
O
Monod
Michel
M
D000626:Aminopeptidases; D000818:Animals; D001232:Aspergillus fumigatus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D002268:Carboxypeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017077:Culture Media, Conditioned; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D010450:Endopeptidases / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010802:Phylogeny; D010843:Pichia / Q000201:enzymology / Q000235:genetics; D011817:Rabbits; D012697:Serine Endopeptidases / Q000378:metabolism
D017077:Culture Media, Conditioned; D005656:Fungal Proteins; D002268:Carboxypeptidases; D010450:Endopeptidases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C048001:tripeptidyl-peptidase 2; D012697:Serine Endopeptidases; C479198:sedolisin