The YΦ Motif Defines the Structure-activity Relationships of Human 20S Proteasome Activators

Overview

Journal Nat Commun

Specialty Biology

Date 2022 Mar 10

PMID 35264557

Authors

Kwadwo A Opoku-Nsiah

Andres H de la Pena

Sarah K Williams

Nikita Chopra

Andrej Sali

Gabriel C Lander

Jason E Gestwicki

Affiliations

Soon will be listed here.

Abstract

The 20S proteasome (20S) facilitates turnover of most eukaryotic proteins. Substrate entry into the 20S first requires opening of gating loops through binding of HbYX motifs that are present at the C-termini of certain proteasome activators (PAs). The HbYX motif has been predominantly characterized in the archaeal 20S, whereas little is known about the sequence preferences of the human 20S (h20S). Here, we synthesize and screen ~120 HbYX-like peptides, revealing unexpected differences from the archaeal system and defining the h20S recognition sequence as the Y-F/Y (YФ) motif. To gain further insight, we create a functional chimera of the optimized sequence, NLSYYT, fused to the model activator, PA26. A cryo-EM structure of PA26-h20S is used to identify key interactions, including non-canonical contacts and gate-opening mechanisms. Finally, we demonstrate that the YФ sequence preferences are tuned by valency, allowing multivalent PAs to sample greater sequence space. These results expand the model for termini-mediated gating and provide a template for the design of h20S activators.

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