catA, a new Aspergillus nidulans gene encoding a developmentally regulated catalase

Area of Science:

• Molecular biology
• Mycology
• Developmental biology

Background:

• Aspergillus nidulans asexual sporulation (conidiation) is a key model for gene regulation and development.
• CAN5 cDNA was identified by its induced transcript during conidiation.

Purpose of the Study:

• To characterize the gene corresponding to CAN5 cDNA.
• To investigate the role of the encoded catalase (catA) in Aspergillus nidulans development and oxidative stress response.

Main Methods:

• Molecular characterization of the catA gene.
• Analysis of catA mRNA expression during conidiation.
• Catalase activity assays using native gels.
• Construction and analysis of catA-disrupted mutants.

Main Results:

• The gene encodes a developmentally regulated catalase, catA, with greater similarity to prokaryotic than fungal catalases.
• catA expression is induced during sporulation but independent of key developmental genes (brlA, abaA, wetA).
• Two catalase activities were detected; catA disruption affected spore catalase, indicating at least two catalase genes. catA-mutant spores showed increased sensitivity to H2O2.

Conclusions:

• catA is a developmentally regulated catalase essential for spore resistance to oxidative stress.
• The findings suggest oxidative stress occurs during Aspergillus nidulans asexual development.
• At least two catalase genes exist in Aspergillus nidulans, with distinct roles in vegetative growth and sporulation.