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Analysis of two Aspergillus nidulans genes encoding extracellular proteases
P A vanKuyk1, B F Cheetham, M E Katz
1Molecular and Cellular Biology Division, University of New England, Armidale, New South Wales, 2351, Australia.
Fungal Genetics and Biology : FG & B
|July 7, 2000
Summary
The Aspergillus nidulans prtA gene produces most extracellular protease activity. A second gene, prtB, encodes a putative aspartic protease with a deletion, and is expressed at low levels.
Area of Science:
- Microbiology
- Molecular Biology
- Enzymology
Background:
- Aspergillus nidulans secretes significant extracellular protease activity.
- The specific genes and mechanisms responsible for this activity, particularly at acidic pH, are not fully understood.
Purpose of the Study:
- To characterize the genetic basis of extracellular protease activity in Aspergillus nidulans.
- To identify and analyze genes encoding proteases, including potential aspartic proteases.
Main Methods:
- Gene disruption to create prtA delta mutants.
- Genetic mapping of the prtA gene to chromosome V.
- Isolation and sequence analysis of the putative aspartic protease gene, prtB.
- Reverse transcription polymerase chain reaction (RT-PCR) to assess prtB gene expression.
Main Results:
- The prtA gene is responsible for the majority of extracellular protease activity at neutral and acidic pH.
- The prtA gene was mapped to chromosome V.
- A gene, prtB, encoding a putative aspartic protease was identified.
- The deduced amino acid sequence of PrtB suggests a deletion near an active site.
- RT-PCR confirmed low-level expression of the prtB gene.
Conclusions:
- PrtA is the primary extracellular protease in Aspergillus nidulans.
- The prtB gene encodes a potentially non-functional or modified aspartic protease due to a significant deletion.
- Further research is needed to elucidate the precise role and regulation of prtB in Aspergillus nidulans.