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dewA encodes a fungal hydrophobin component of the Aspergillus spore wall
1Department of Genetics, University of Georgia, Athens 30602, USA.
Abstract:
An anonymous cDNA clone, pCAN4, was shown previously to correspond to an mRNA that accumulates preferentially during asexual sporulation of the filamentous fungus Aspergillus nidulans. The peptide encoded by pCAN4 is a fungal hydrophobin, a group of small, hydrophobic cell wall proteins. When the CAN4 gene was disrupted, conidia and conidiophores appeared to be normal, but sporulating colonies wetted more rapidly with detergent solutions than did the wild type. We renamed CAN4 dewA for the detergent wettable phenotype and mapped it to chromosome V, 24 map units from cysC. The A. nidulans rodA gene also encodes a sporulation-specific fungal hydrophobin. Spores of a dewA- rodA- double mutant were less hydrophobic than those of either mutant alone, showing that dewA and rodA contribute independently to spore-wall hydrophobicity. Immunolocalization of DewA by epitope tagging demonstrated that DewA is present in the spore wall, but not in the walls of germ tubes, hyphae or cells of the spore-producing conidiophore. We conclude that dewA encodes a new fungal hydrophobin component of the conidial wall.
Insights
The Aspergillus nidulans dewA gene encodes a hydrophobin essential for spore-wall hydrophobicity. Disruption of dewA leads to faster wetting of sporulating colonies, indicating its role in fungal development.
Area of Science:
- Mycology
- Biochemistry
- Genetics
Background:
- Hydrophobins are small, hydrophobic proteins found in fungal cell walls.
- Asexual sporulation in Aspergillus nidulans involves the accumulation of specific mRNAs.
- The previously identified cDNA clone pCAN4 corresponds to a hydrophobin involved in sporulation.
Purpose of the Study:
- To investigate the function of the gene encoded by pCAN4, renamed dewA.
- To determine the role of DewA in the hydrophobicity of Aspergillus nidulans spores.
- To elucidate the contribution of dewA and rodA to spore-wall properties.
Main Methods:
- Gene disruption of CAN4 (dewA) in Aspergillus nidulans.
- Phenotypic analysis of sporulating colonies, including wetting assays with detergent solutions.
- Genetic analysis of a dewA- rodA- double mutant.
- Immunolocalization of DewA using epitope tagging.
Main Results:
- Disruption of dewA resulted in sporulating colonies that wetted more rapidly with detergent solutions.
- A dewA- rodA- double mutant exhibited reduced spore hydrophobicity compared to single mutants.
- DewA was localized to the spore wall, but not to other fungal structures.
Conclusions:
- dewA encodes a novel fungal hydrophobin that is a component of the conidial wall.
- DewA independently contributes to the overall hydrophobicity of Aspergillus nidulans spores.
- The dewA gene plays a significant role in the surface properties of fungal spores.