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Intracellular β-glucosidase regulates cellulase expression and development in Aspergillus nidulans
Shun Yakabe1, Chihiro Kadooka1,2, Tomohiko Matsuzawa3
1Division of Applied Microbial Technology, Graduate School of Engineering, Sojo University, 4-22-1 Ikeda, Nishi-Ku, Kumamoto, 860-0082, Japan.
Applied Microbiology and Biotechnology
|May 4, 2026
Summary
The intracellular enzyme CbgA acts as a crucial signal gatekeeper in Aspergillus nidulans, controlling cellobiose levels to balance fungal development and metabolism. Its absence leads to metabolic defects, highlighting its role in regulating enzyme activity.
Area of Science:
- * Molecular and Cellular Biology
- * Mycology
- * Biochemistry
Background:
- * Intracellular β-glucosidases play vital roles in filamentous fungi, but their physiological functions are not fully understood.
- * β-Glucosidases (EC 3.2.1.21) are key enzymes in biomass degradation and metabolic regulation.
- * Aspergillus nidulans serves as a model organism for studying fungal physiology and gene function.
Purpose of the Study:
- * To characterize the roles of two intracellular β-glucosidases, CbgA and CbgB, in Aspergillus nidulans.
- * To elucidate the physiological impact of CbgA on cellulase activity, secondary metabolism, and fungal development.
- * To investigate the mechanism by which CbgA regulates intracellular cellobiose levels and its downstream effects.
Main Methods:
- * Gene deletion and construction of mutant strains (ΔcbgA, ΔcltB).
- * Biochemical assays to analyze enzyme activity and metabolite accumulation.
- * Phenotypic analysis including conidiation, secondary metabolite production, and cellulase activity.
Main Results:
- * CbgA was identified as the predominant intracellular β-glucosidase in Aspergillus nidulans.
- * Deletion of cbgA resulted in overactivated cellulases, cellobiose-dependent accumulation of secondary metabolites, and reduced conidiation.
- * Deletion of the cellobiose transporter gene cltB in the ΔcbgA background significantly attenuated these phenotypes, confirming the role of intracellular cellobiose.
Conclusions:
- * CbgA functions as a critical "signal gatekeeper" by modulating intracellular cellobiose levels, thereby regulating cellulase expression and fungal development.
- * Maintaining physiological intracellular cellobiose concentrations by CbgA is essential for preventing metabolic imbalance and ensuring proper coordination between nutrient transport and metabolism.
- * Targeting CbgA activity offers a potential strategy for optimizing cellulase production in fungal biotechnology applications.
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