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Analysis of the extracellular proteome from single deleted LPMO9s Aspergillus nidulans mutants growing in Avicel

ABSTRACT: Lytic polysaccharide monooxygenases (LPMOs) are oxidative enzymes found in viruses, archaea, bacteria as well as eukaryotes, such as fungi, algae and insects, actively contributing to the degradation of different polysaccharides. In Aspergillus nidulans, LPMOs from family AA9 (AnLPMO9s), along with an AA3 cellobiose dehydrogenase (AnCDH1), are co-secreted upon growth on crystalline cellulose and lignocellulosic substrates, indicating their role in the degradation of plant cell wall components. Functional analysis revealed that the three main secreted LPMO9s (AnLPMO9C, AnLPMO9F and AnLPMO9G) correspond to cellulose- active enzymes with distinct regioselectivity. Deletion and overexpression studies confirmed that the abundantly secreted AnLPMO9F is a major component of the extracellular cellulolytic system, while AnLPMO9G, less abundant in the secretome, has an important role by oxidizing crystalline fractions of cellulose. Single or double deletion of these AnLPMO9s partially impair fungal growth on sugarcane straw but not on crystalline cellulose, demonstrating the importance of LPMO9s for the saprophytic fungal lifestyle in the degradation of complex lignocellulosic substrates. Although the deletion of AnCDH1 slightly reduced the cellulolytic activity, it did not affect fungal growth indicating the existence of other electron donors to LPMOs. Additionally, double or triple knockouts of these enzymes had no accumulative deleterious effect on the cellulolytic activity nor on fungal growth, regardless of the deleted gene. The extracelllular proteomes of single deleted mutants growing in Avicel was analysed on a Q-TOF mass spectrometer and revealed an overall reduction in cellulase secretion, and some specifically some changes in the secretion of some enzymes, suggesting an adaptive mechanism adopted to compensate LPMO9s absence during cellulose degradation. Overexpression of AnLPMO9s in a cellulose-induced secretome background confirmed the importance and applicability of AnLPMO9G to improve lignocellulose saccharification.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Emericella Nidulans (strain Fgsc A4 / Atcc 38163 / Cbs 112.46 / Nrrl 194 / M139) (aspergillus Nidulans)

TISSUE(S): Fungal Cell

SUBMITTER: Marcelo Rubio

LAB HEAD: André Damásio

PROVIDER: PXD031881 | Pride | 2022-05-09

REPOSITORIES: Pride

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Analysis of the extracellular proteome from single deleted LPMO9s Aspergillus nidulans mutants growing in Avicel

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