A constitutive mutation in a posttranscriptional regulator gene for a phenoloxidase and proteases in Podospora anserina

Abstract

A recessive mutation in the gene mod-2 results in the synthesis at low temperatures of a phenoloxidase and an arrest of growth, reversible by β-phenylpyruvic acid, a protease inhibitor. Phenoloxidase synthesis is 5-fluorouracil resistant and cycloheximide sensitive. Suppression of both cold sensitivity and phenoloxidase synthesis by common factors (higher NH ⁺₄ concentrations or mutations) suggests that the protease, suspected to be responsible for cold sensitivity, also arises from preexisting mRNA molecules. Instead of being recessive and constitutive, the mod-2 mutation is suppressive and dominant when cold sensitivity and phenoloxidase synthesis are induced as the consequence of the nonallelic gene interactions C/D, C/E, or R/V responsible for protoplasmic incompatibility. Combinations of nonallelic incompatibility systems and several mod-2 mutations lead us to hypothesize that the translational control of the above proteins depends on conformational relationships between incompatibility gene products and mod-2.