The translation termination factor eRF1 (Sup45p) of Saccharomyces cerevisiae is required for pseudohyphal growth and invasion.

Mutations in the essential genes SUP45 and SUP35, encoding yeast translation termination factors eRF1 and eRF3, respectively, lead to a wide range of phenotypes and affect various cell processes. In this work, we show that nonsense and missense mutations in the SUP45, but not the SUP35, gene abolish diploid pseudohyphal and haploid invasive growth. Missense mutations that change phosphorylation sites of Sup45 protein do not affect the ability of yeast strains to form pseudohyphae. Deletion of the C-terminal part of eRF1 did not lead to impairment of filamentation. We show a correlation between the filamentation defect and the budding pattern in sup45 strains. Inhibition of translation with specific antibiotics causes a significant reduction in pseudohyphal growth in the wild-type strain, suggesting a strong correlation between translation and the ability for filamentous growth. Partial restoration of pseudohyphal growth by addition of exogenous cAMP assumes that sup45 mutants are defective in the cAMP-dependent pathway that control filament formation.