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Two new genes involved in signalling ambient pH in Aspergillus nidulans
H N Arst1, E Bignell, J Tilburn
1Department of Infectious Diseases and Bacteriology, Royal Postgraduate Medical School, London, England.
Abstract:
Two new genes, palH and palI, where mutations mimic the effects of acidic growth pH have been identified in Aspergillus nidulans. A palH mutation is phenotypically indistinguishable from mutations in the palA, palB, palC, and palF genes, whereas palI mutations differ only in that they allow some growth at pH 8. Mutations in palA, B, C, F, and H are epistatic to a palI mutation and the significance of this epistasis is discussed. Additionally, palE and palB mutations have been shown to be allelic. Thus, a total of six genes where mutations mimic acidic growth conditions has been identified.
Insights
Researchers identified two new genes, palH and palI, in Aspergillus nidulans that affect growth pH. These findings expand the understanding of pH regulation in fungi.
Area of Science:
- Molecular Biology
- Mycology
- Genetics
Background:
- Fungal growth is sensitive to environmental pH.
- Genetic factors influencing pH homeostasis are crucial for fungal development.
- Previous studies identified several genes involved in pH regulation in Aspergillus nidulans.
Purpose of the Study:
- To identify novel genes in Aspergillus nidulans involved in regulating acidic growth pH.
- To characterize the function and genetic interactions of newly identified pH-related genes.
Main Methods:
- Mutagenesis screening to identify genes affecting growth pH.
- Phenotypic analysis of mutant strains under varying pH conditions.
- Epistasis analysis to determine gene interactions and order in regulatory pathways.
- Allele testing to confirm allelism between palE and palB mutations.
Main Results:
- Two new genes, palH and palI, were identified, with mutations mimicking acidic growth pH.
- palH mutations showed indistinguishable phenotypes from previously known pal genes (palA, palB, palC, palF).
- palI mutations allowed limited growth at alkaline pH (pH 8), distinguishing them from other pal mutations.
- Mutations in palA, palB, palC, palF, and palH were epistatic to palI mutations.
- palE and palB mutations were found to be allelic.
- A total of six genes affecting acidic growth conditions have now been identified.
Conclusions:
- The identification of palH and palI expands the known genetic network controlling pH homeostasis in Aspergillus nidulans.
- The distinct phenotype of palI suggests a unique role in pH regulation, potentially involving both acidic and alkaline tolerance.
- The observed epistasis provides insights into the hierarchical organization of pH regulatory pathways.
- The allelism of palE and palB simplifies the genetic map of pH-related genes.