Biochemistry, Molecular Biology, and Cell Biology of Yeast and Fungal Catalases

Abstract

Catalases appear to be an important part of the system that virtually all cells growing under aerobic conditions possess for their defense against oxidative stress. There is little hard evidence from all types of organisms to support this statement. Whether these enzymes in vivo act as true catalases, or in a way that is not yet completely understood, has not been clarified. Which type of organism should be chosen to study catalases? It should be a system that can be studied well using different approaches. Obviously, this organism should contain catalases in reasonably high amounts; preferably, these amounts should be variable and should depend on physiological conditions. Furthermore, studies on this organism would be more attractive if its catalase content had some practical importance; e.g., in biotechnology or agriculture. This could be used as an argument for studying catalases of Saccharomyces cerevisiae or of other yeasts. Indeed, the catalases of these organisms have been investigated fairly extensively for this and other reasons. A reasonable amount of information has accumulated and is reviewed here, with particular emphasis on S. cerevisiae.

STRUCTURE AND BIOCHEMISTRY OF YEAST AND FUNGAL CATALASES
Generally, catalases of microorganisms are a more diverse group of enzymes than those from animals and plants. Nevertheless, in yeasts and fungi almost exclusively heme-containing catalases are found. No manganese catalases have been reported, but two catalase-peroxidases from Septoria tritici and Penicillium simplicissimum are known, so far the sole eukaryotic members of this subtype. Only a handful of these catalases have been investigated...