Multiple Catalase Genes Are Differentially Regulated in Aspergillus nidulans
Open Access
- 15 February 2001
- journal article
- research article
- Published by American Society for Microbiology in Journal of Bacteriology
- Vol. 183 (4) , 1434-1440
- https://doi.org/10.1128/jb.183.4.1434-1440.2001
Abstract
Detoxification of hydrogen peroxide is a fundamental aspect of the cellular antioxidant responses in which catalases play a major role. Two differentially regulated catalase genes, catA andcatB, have been studied in Aspergillus nidulans. Here we have characterized a third catalase gene, designated catC, which predicts a 475-amino-acid polypeptide containing a peroxisome-targeting signal. With a molecular mass of 54 kDa, CatC shows high similarity to other small-subunit monofunctional catalases and is most closely related to catalases from other fungi, Archaea, and animals. In contrast, the CatA (∼84 kDa) and CatB (∼79 kDa) enzymes belong to a family of large-subunit catalases, constituting a unique fungal and bacterial group. The catC gene displayed a relatively constant pattern of expression, not being induced by oxidative or other types of stress. Targeted disruption of catC eliminated a constitutive catalase activity not detected previously in zymogram gels. However, a catalase activity detected in catA catBmutant strains during late stationary phase was still present incatC and catABC null mutants, thus demonstrating the presence of a fourth catalase, here named catalase D (CatD). Neither catC nor catABC triple mutants showed any developmental defect, and both mutants grew as well as wild-type strains in H2O2-generating substrates, such as fatty acids, and/or purines as the sole carbon and nitrogen sources, respectively. CatD activity was induced during late stationary phase by glucose starvation, high temperature, and, to a lesser extent, H2O2 treatment. The existence of at least four differentially regulated catalases indicates a large and regulated capability for H2O2detoxification in filamentous fungi.This publication has 54 references indexed in Scilit:
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