Protoplasmic incompatibility and self-lysis in Podospora anserina: enzyme activities associated with cell destruction

Abstract

In the fungus Podospora anserina protoplasmic incompatibility, a phenomenon of cell destruction resulting from the presence in a common cytoplasm of nonallelic incompatible genes, is associated with the appearance of specific proteolytic activities and a phenoloxidase absent from normal cells. We have now shown that during cell lysis, the levels of four additional enzymes increase significantly (3- to 10-fold): a second phenoloxidase, a malate dehydrogenase, a reduced nicotinamide adenine dinucleotide dehydrogenase, and an amino acid oxidase. These increases were inhibited by cycloheximide but unaffected by 5-fluorouracil and actinomycin D or β-phenyl pyruvic acid, an inhibitor of the proteases specific to disintegrating cells. The increase of these four enzymes was shown to be suppressed by mutations in modifier genes known to prevent cell destruction and to inhibit the formation of the proteolytic enzymes.