Unveiling a classical mutant in the context of the GH3 β-glucosidase family in Neurospora crassa
Classical fungal mutant strains obtained by mutagenesis have helped to elucidate fundamental metabolic pathways in the past. In the filamentous fungus Neurospora crassa , the gluc-1 strain was isolated long ago and characterized by its low level of β-glucosidase activity, which is essential for the...
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Published in | AMB Express Vol. 14; no. 1; p. 4 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Berlin/Heidelberg
Springer Berlin Heidelberg
05.01.2024
Springer Nature B.V Springer SpringerOpen |
Subjects | |
Online Access | Get full text |
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Summary: | Classical fungal mutant strains obtained by mutagenesis have helped to elucidate fundamental metabolic pathways in the past. In the filamentous fungus
Neurospora crassa
, the
gluc-1
strain was isolated long ago and characterized by its low level of β-glucosidase activity, which is essential for the degradation of cellulose, the most abundant biopolymer on Earth and the main polymeric component of the plant cell wall. Based on genomic resequencing, we hypothesized that the causative mutation resides in the β-glucosidase gene
gh3-3
(
bgl6, NCU08755
). In this work, growth patterns, enzymatic activities and sugar utilization rates were analyzed in several mutant and overexpression strains related to
gluc-1
and
gh3-3
. In addition, different mutants affected in the degradation and transport of cellobiose were analyzed. While overexpression of
gh3-3
led to the recovery of β-glucosidase activity in the
gluc-1
mutant, as well as normal utilization of cellobiose, the full gene deletion strain Δ
gh3-3
was found to behave differently than
gluc-1
with lower secreted β-glucosidase activity, indicating a dominant role of the amino acid substitution in the point mutated
gh3-3
gene of
gluc-1
. Our results furthermore confirm that GH3-3 is the major extracellular β-glucosidase in
N. crassa
and demonstrate that the two cellodextrin transporters CDT-1 and CDT-2 are essential for growth on cellobiose when the three main
N. crassa
β-glucosidases are absent. Overall, these findings provide valuable insight into the mechanisms of cellulose utilization in filamentous fungi, being an essential step in the efficient production of biorefinable sugars from agricultural and forestry plant biomass. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 USDOE AC05-76RL01830 PNNL-SA-194079 |
ISSN: | 2191-0855 2191-0855 |
DOI: | 10.1186/s13568-023-01658-0 |