title: Secreted glutamic protease rescues aspartic protease Pep deficiency in Aspergillus fumigatus during growth in acidic protein medium.
abstract: In an acidic protein medium Aspergillus fumigatus secretes an aspartic endoprotease (Pep) as well as tripeptidyl-peptidases, a prolyl-peptidase and carboxypeptidases. In addition, LC-MS/MS revealed a novel glutamic protease, AfuGprA, homologous to Aspergillus niger aspergillopepsin II. The importance of AfuGprA in protein digestion was evaluated by deletion of its encoding gene in A. fumigatus wild-type D141 and in a pepΔ mutant. Either A. fumigatus Pep or AfuGprA was shown to be necessary for fungal growth in protein medium at low pH. Exoproteolytic activity is therefore not sufficient for complete protein hydrolysis and fungal growth in a medium containing proteins as the sole nitrogen source. Pep and AfuGprA constitute a pair of endoproteases active at low pH, in analogy to A. fumigatus alkaline protease (Alp) and metalloprotease I (Mep), where at least one of these enzymes is necessary for fungal growth in protein medium at neutral pH. Heterologous expression of AfuGprA in Pichia pastoris showed that the enzyme is synthesized as a preproprotein and that the propeptide is removed through an autoproteolytic reaction at low pH to generate the mature protease. In contrast to A. niger aspergillopepsin II, AfuGprA is a single-chain protein and is structurally more similar to G1 proteases characterized in other non-Aspergillus fungi.
authors.affiliation: Department of Dermatology, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
authors.forename: Dev
authors.initials: D
authors.lastname: Sriranganadane
authors.affiliation: Department of Medical Microbiology and National Reference Centre for Systemic Mycoses, University Hospital of Göttingen, Germany.
authors.forename: Utz
authors.initials: U
authors.lastname: Reichard
authors.affiliation: Department of Dermatology, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
authors.forename: Karine
authors.initials: K
authors.lastname: Salamin
authors.affiliation: Department of Dermatology, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
authors.forename: Marina
authors.initials: M
authors.lastname: Fratti
authors.affiliation: Centre for Integrative Biology (CIBIO), University of Trento, Italy.
authors.forename: Olivier
authors.initials: O
authors.lastname: Jousson
authors.affiliation: Protein Analysis Facility, Centre for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Patrice
authors.initials: P
authors.lastname: Waridel
authors.affiliation: Protein Analysis Facility, Centre for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Manfredo
authors.initials: M
authors.lastname: Quadroni
authors.affiliation: Laboratory of Molecular and Cellular Biology, University of Neuchâtel, rue E-Argand 11, 2009 Neuchâtel, Switzerland.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Neuhaus
authors.affiliation: Department of Dermatology, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
authors.forename: Michel
authors.initials: M
authors.lastname: Monod
mesh_terms: D000143:Acids / Q000378:metabolism; D000595:Amino Acid Sequence; D057055:Aspartic Acid Proteases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001232:Aspergillus fumigatus / Q000201:enzymology* / Q000254:growth & development* / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry* / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport
chemical_list: D000143:Acids; D003470:Culture Media; D005656:Fungal Proteins; D018698:Glutamic Acid; D057055:Aspartic Acid Proteases; D010447:Peptide Hydrolases