Distinct Regulatory Ribosomal Ubiquitylation events are reversible and hierarchically organized

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Abstract

Activation of the integrated stress response (ISR) or the ribosome-associated quality control (RQC) pathway stimulates regulatory ribosomal ubiquitylation (RRub) on distinct 40S ribosomal proteins, yet the cellular role and fate of ubiquitylated proteins remain unclear. We demonstrate that uS10 and uS5 ubiquitylation are dependent upon eS10 or uS3 ubiquitylation, respectively, suggesting that a hierarchical relationship exists among RRub events establishing a ubiquitin code on ribosomes. We show that stress dependent RRub events diminish after initial stimuli and that RRub loss is the result of demodification by deubiquitylating enzymes rather than protein degradation. Utilizing an optical RQC reporter we identify OTUD3 and USP21 as deubiquitylating enzymes that antagonize ZNF598-mediated 40S ubiquitylation and can limit RQC activation. Critically, cells lacking USP21 or OTUD3 have altered RQC activity and delayed eS10 deubiquitylation indicating a functional role for deubiquitylating enzymes within the RQC pathway.

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Danielle M Garshott

Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-4357-1781
Elayanambi Sundaramoorthy

Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-1256-9758
Marilyn Leonard

Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, United States

Competing interests
The authors declare that no competing interests exist.
Eric J Bennett

Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, United States

For correspondence
e1bennett@ucsd.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-1201-3314

Funding

National Institutes of Health (DP2-GM119132)

Eric J Bennett

National Institutes of Health (PGM085764)

Eric J Bennett

National Science Foundation (DGE-1650112)

Danielle M Garshott

The authors declare that the funders had no role in designing this study, data collection, or interpretation.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.