The intrinsically disordered Sem1 protein functions as a molecular tether during proteasome lid biogenesis.

ABSTRACT: The intrinsically disordered yeast protein Sem1 (DSS1 in mammals) participates in multiple protein complexes, including the proteasome, but its role(s) within these complexes is uncertain. We report that Sem1 enforces the ordered incorporation of subunits Rpn3 and Rpn7 into the assembling proteasome lid. Sem1 uses conserved acidic segments separated by a flexible linker to grasp Rpn3 and Rpn7. The same segments are used for protein binding in other complexes, but in the proteasome lid they are uniquely deployed for recognizing separate polypeptides. We engineered TEV protease-cleavage sites into Sem1 to show that the tethering function of Sem1 is important for the biogenesis and integrity of the Rpn3-Sem1-Rpn7 ternary complex but becomes dispensable once the ternary complex incorporates in

SUBMITTER: Tomko RJ 

PROVIDER: S-EPMC3947554 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature