摘要
Centromeres are chromosomal loci marked by histone variant Cen H3(centromeric histone H3)and essential for genomic stability and cell division.The budding yeast E3 ubiquitin ligase Psh1 selectively recognizes the yeast Cen H3(Cse4)for ubiquitination and controls the cellular level of Cse4 for proteolysis,but the underlying mechanism remains largely unknown.Here,we show that Psh1 uses a Cse4-binding domain(CBD,residues 1-211)to interact with Cse4-H4 instead of H3-H4,yielding a dissociation constant(Kd)of 27 nM.Psh1 recognizes Cse4-specific residues in the L1 loop and a2 helix to ensure Cse4 binding and ubiquitination.We map the Psh1-binding region of Cse4-H4 and identify a wide range of Cse4-specific residues required for the Psh1-mediated Cse4 recognition and ubiquitination.Further analyses reveal that histone chaperone Scm3 can impair Cse4 ubiquitination by abrogating Psh1-Cse4 binding.Together,our study reveals a novel Cse4-binding mode distinct from those of known Cen H3 chaperones and elucidates the mechanism by which Scm3 competes with Psh1 for Cse4 binding.
基金
supported by the grants from Natural Science Foundation of China(31521002,31970621,31871318,31671344,31801070)
National Key Research and Development Program of China(2019YFA0508902)
Strategic Priority Research Program(XDB37010100)。
