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Neuhaus, Jean-Marc

Nom
Neuhaus, Jean-Marc
Affiliation principale
Fonction
Professeur ordinaire
Email
jean-marc.neuhaus@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/300

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  • Publication
    Métadonnées seulement
    Secreted glutamic protease rescues aspartic protease Pep deficiency in Aspergillus fumigatus during growth in acidic protein medium
    (2011)
    Sriranganadane, D.
    ;
    Reichard, U.
    ;
    Salamin, K.
    ;
    Fratti, M.
    ;
    Jousson, O.
    ;
    Waridel, P.
    ;
    Quadroni, M.
    ;
    Neuhaus, Jean-Marc 
    ;
    Monod, M.
    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 pepDelta 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.
  • Publication
    Métadonnées seulement
    Identification of novel secreted proteases during extracellular proteolysis by dermatophytes at acidic pH
    (2011)
    Sriranganadane, D.
    ;
    Waridel, P.
    ;
    Salamin, K.
    ;
    Feuermann, M.
    ;
    Mignon, B.
    ;
    Staib, P.
    ;
    Neuhaus, Jean-Marc 
    ;
    Quadroni, M.
    ;
    Monod, M.
    The dermatophytes are a group of closely related fungi which are responsible for the great majority of superficial mycoses in humans and animals. Among various potential virulence factors, their secreted proteolytic activity attracts a lot of attention. Most dermatophyte-secreted proteases which have so far been isolated in vitro are neutral or alkaline enzymes. However, inspection of the recently decoded dermatophyte genomes revealed many other hypothetical secreted proteases, in particular acidic proteases similar to those characterized in Aspergillus spp. The validation of such genome predictions instigated the present study on two dermatophyte species, Microsporum canis and Arthroderma benhamiae. Both fungi were found to grow well in a protein medium at acidic pH, accompanied by extracellular proteolysis. Shotgun MS analysis of secreted protein revealed fundamentally different protease profiles during fungal growth in acidic versus neutral pH conditions. Most notably, novel dermatophyte-secreted proteases were identified at acidic pH such as pepsins, sedolisins and acidic carboxypeptidases. Therefore, our results not only support genome predictions, but demonstrate for the first time the secretion of acidic proteases by dermatophytes. Our findings also suggest the existence of different pathways of protein degradation into amino acids and short peptides in these highly specialized pathogenic fungi.
  • Publication
    Métadonnées seulement
    Aspergillus protein degradation pathways with different secreted protease sets at neutral and acidic pH
    (2010)
    Sriranganadane, D.
    ;
    Waridel, P.
    ;
    Salamin, K.
    ;
    Reichard, U.
    ;
    Grouzmann, E.
    ;
    Neuhaus, Jean-Marc 
    ;
    Quadroni, M.
    ;
    Monod, M.
    Aspergillus fumigatus grows well at neutral and acidic pH in a medium containing protein as the sole nitrogen source by secreting two different sets of proteases. Neutral pH favors the secretion of neutral and alkaline endoproteases, leucine aminopeptidases (Laps) which are nonspecific monoaminopeptidases, and an X-prolyl dipeptidase (DppIV). Acidic pH environment promotes the secretion of an aspartic endoprotease of pepsin family (Pep1) and tripeptidyl-peptidases of the sedolisin family (SedB and SedD). A novel prolyl peptidase, AfuS28, was found to be secreted in both alkaline and acidic conditions. In previous studies, Laps were shown to degrade peptides from their N-terminus until an X-Pro sequence acts as a stop signal. X-Pro sequences can be then removed by DppIV, which allows Laps access to the following residues. We have shown that at acidic pH Seds degrade large peptides from their N-terminus into tripeptides until Pro in P1 or P'1 position acts as a stop for these exopeptidases. However, X-X-Pro and X-X-X-Pro sequences can be removed by AfuS28 thus allowing Seds further sequential proteolysis. In conclusion, both alkaline and acidic sets of proteases contain exoprotease activity capable of cleaving after proline residues that cannot be removed during sequential digestion by nonspecific exopeptidases.