Deficiency in homogentisic acid oxidase activity associated with the brown phenotype of Dictyostelium discoideum.

Mutations at the bwnA locus of Dictyostelium discoideum were found to result in drastically reduced levels of activity of the enzyme homogentisic acid oxidase. It is proposed that the brown phenotype associated with these mutations results from the accumulation of an intermediate in the tyrosine degradative pathway, homogentisic acid, and its subsequent spontaneous oxidation. This knowledge is used to devise improved screening procedures potentially useful in the parasexual genetics system of this organism.