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The Loss-of-Function Mutation aldA67 Leads to Enhanced α-L-Rhamnosidase Production by Aspergillus nidulans
- Source :
- Journal of Fungi, Vol 8, Iss 11, p 1181 (2022)
- Publication Year :
- 2022
- Publisher :
- MDPI AG, 2022.
-
Abstract
- In Aspergillus nidulans L-rhamnose is catabolised to pyruvate and L-lactaldehyde, and the latter ultimately to L-lactate, via the non-phosphorylated pathway (LRA) encoded by the genes lraA-D, and aldA that encodes a broad substrate range aldehyde dehydrogenase (ALDH) that also functions in ethanol utilisation. LRA pathway expression requires both the pathway-specific transcriptional activator RhaR (rhaR is expressed constitutively) and the presence of L-rhamnose. The deletion of lraA severely impairs growth when L-rhamnose is the sole source of carbon and in addition it abolishes the induction of genes that respond to L-rhamnose/RhaR, indicating that an intermediate of the LRA pathway is the physiological inducer likely required to activate RhaR. The loss-of-function mutation aldA67 also has a severe negative impact on growth on L-rhamnose but, in contrast to the deletion of lraA, the expression levels of L-rhamnose/RhaR-responsive genes under inducing conditions are substantially up-regulated and the production of α-L-rhamnosidase activity is greatly increased compared to the aldA+ control. These findings are consistent with accumulation of the physiological inducer as a consequence of the loss of ALDH activity. Our observations suggest that aldA loss-of-function mutants could be biotechnologically relevant candidates for the over-production of α-L-rhamnosidase activity or the expression of heterologous genes driven by RhaR-responsive promoters.
Details
- Language :
- English
- ISSN :
- 2309608X
- Volume :
- 8
- Issue :
- 11
- Database :
- Directory of Open Access Journals
- Journal :
- Journal of Fungi
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.b731d009962c4a52b3cd620bbbdc35f6
- Document Type :
- article
- Full Text :
- https://doi.org/10.3390/jof8111181