Dataset Information

The RNA-binding ubiquitin ligase MKRN1 acts as a sensor for ribosome-associated quality control of poly(A)-translation

ABSTRACT: Human cells have evolved multiple quality control mechanisms to ensure protein homeostasis by detecting aberrant mRNAs and protein products which are condemned for rapid decay. Translating ribosomes that run into poly(A) tails are terminally stalled, followed by ribosome recycling and rapid decay of the truncated nascent polypeptide via the ribosome-associated quality control (RQC). Here, we demonstrate that the conserved RNA-binding E3 ubiquitin ligase Makorin Ring Finger Protein 1 (MKRN1) acts as a novel sensor of poly(A) sequences to initiate ribosome stalling in RQC. Using individual-nucleotide resolution UV crosslinking and immunoprecipitation (iCLIP), we show that MKRN1 is positioned upstream of A-rich stretches and poly(A) tails in mRNAs via interaction with the cytoplasmic poly(A)-binding protein (PABP). Ubiquitin remnant profiling uncovers PABP and ribosomal protein RPS10 as well as multiple translational regulators as main targets of MRKN1-mediated ubiquitylation. The modified lysine in RPS10 is distinct from the main target sites of ZNF598, the second E3 ubiquitin ligase involved in initial ribosome stalling, indicating that multiple modifications need to converge to prevent promiscuous ubiquitylation of lysine-translating ribosomes. We propose that MKRN1 serves as a first line of poly(A) recognition at the RNA level to prevent erroneous protein products and maintain proteome integrity.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Petra Beli

LAB HEAD: Petra Beli

PROVIDER: PXD011772 | Pride | 2019-08-19

REPOSITORIES: Pride

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Publications

The RNA-binding ubiquitin ligase MKRN1 functions in ribosome-associated quality control of poly(A) translation.

Hildebrandt Andrea A Brüggemann Mirko M Rücklé Cornelia C Boerner Susan S Heidelberger Jan B JB Busch Anke A Hänel Heike H Voigt Andrea A Möckel Martin M MM Möckel Martin M MM Ebersberger Stefanie S Scholz Anica A Dold Annabelle A Schmid Tobias T Ebersberger Ingo I Roignant Jean-Yves JY Zarnack Kathi K König Julian J Beli Petra P

Genome biology 20191022 1

<h4>Background</h4>Cells have evolved quality control mechanisms to ensure protein homeostasis by detecting and degrading aberrant mRNAs and proteins. A common source of aberrant mRNAs is premature polyadenylation, which can result in non-functional protein products. Translating ribosomes that encounter poly(A) sequences are terminally stalled, followed by ribosome recycling and decay of the truncated nascent polypeptide via ribosome-associated quality control.<h4>Results</h4>Here, we demonstrat ...[more]

PMID: 31640799

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Project description:Translation elongation rates are regulated to ensure proper conformation and biological function of proteins. Translation of either non-stop mRNA or transcripts coding for poly-basic sequences induces ribosome stalling, and the arrest product is degraded by the ribosome-mediated quality control system (RQC). During this process, the stalled ribosome is dissociated into subunits, and the polypeptide is ubiquitinated by the E3 ubiquitin ligase Listerin on the 60S large ribosomal subunit (LSU) leading to subsequent proteasomal degradation. However, it is largely unknown how stalled ribosomes are recognized and dissociated into subunits. Here we report that ubiquitination of the ribosomal protein uS10 by the E3 ubiquitin ligase Hel2 is required for the production of the RQC substrate. RQC-trigger (RQT) factors, a RNA helicase-family protein Slh1/Rqt2, ubiquitin binding protein Cue3/Rqt3 and yKR023W/Rqt4, were also required for the primary steps of RQC, and associated with Hel2-ribosome complexes. Rqt2-4 factors were dispensable for the ubiquitination of uS10 by Hel2/Rqt1 and associated with ribosomes independent of the ubiquitination of uS10. However, the ubiquitin-binding activity of Rqt3 were crucial to trigger RQC. Cryo-electron microscopy (cryo-EM) analysis revealed that Hel2 bound ribosomes are in an rotated state containing hybrid state AP- and PE-tRNAs. Furthermore, ribosome profiling revealed that short footprints, hallmarks of hybrid state ribosomes18, were accumulated at tandem CGA rare codons at the beginning of the poly arginine stalling sequence and long footprints at subsequent codons, respectively. Short footprints at CGA codons were decreased in rqt1 mutant but drastically increased in uS10 mutants defective in the ubiquitination or rqt2 mutant. Collectively, our results demonstrate that Hel2 stabilizes ratcheted ribosomes leading to ubiquitination of uS10. Subsequently, Rqt2-4 factors target these hybrid state ribosomes specifically, allowing subsequent RQC reactions.

Dataset Information

The RNA-binding ubiquitin ligase MKRN1 acts as a sensor for ribosome-associated quality control of poly(A)-translation

Publications

The RNA-binding ubiquitin ligase MKRN1 functions in ribosome-associated quality control of poly(A) translation.

Similar Datasets

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