STUbL-mediated degradation of the transcription factor MATα2 requires degradation elements that coincide with corepressor binding sites.

摘要: The yeast transcription factor MATα2 (α2) is a short-lived protein known to be ubiquitylated by two distinct pathways, one involving the ubiquitin-conjugating enzymes (E2s) Ubc6 and Ubc7 ubiquitin ligase (E3) Doa10 other operating with E2 Ubc4 heterodimeric E3 Slx5/Slx8. Although Slx5/Slx8 small ubiquitin-like modifier (SUMO)-targeted (STUbL), it does not require SUMO target α2 but instead directly recognizes α2. Little about determinants required for its Ubc4- STUbL-mediated degradation or how these substitute in recognition STUbL pathway. We describe elements within α2, both of which are necessary specifically can ubiquitylate C-terminal fragment mutating impairs this ubiquitylation. Surprisingly, identified here overlap specific interaction sites corepressors: Mcm1 site central linker Ssn6 (Cyc8) binding homeodomain. propose that competitive ubiquitylation machinery cofactors balanced so function repression yet short lived enough allow cell-type switching.