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Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses
11:19

Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses

Published on: February 25, 2011

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The Rqc2/Tae2 subunit of the ribosome-associated quality control (RQC) complex marks ribosome-stalled nascent

Ryo Yonashiro1, Erich B Tahara1, Mario H Bengtson1

  • 1Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, United States.

Elife
|March 5, 2016
PubMed

Insights

Ribosome stalling triggers a quality control pathway. This pathway modifies stalled proteins with CAT tails, causing them to aggregate and marking them for degradation.

Area of Science:

  • Molecular Biology
  • Protein Quality Control
  • Translation Regulation

Background:

  • Ribosome stalling during protein synthesis is a cellular stress that can be detrimental.
  • A conserved ribosome-associated quality control (RQC) pathway surveys stalled translation.
  • The RQC complex targets stalled nascent polypeptides (NCs) and associated mRNA for degradation.

Purpose of the Study:

  • To elucidate the function of CAT tails, alanine- and threonine-rich extensions added by Rqc2.
  • To determine the fate of CAT tail-modified (CATylated) nascent chains.
  • To investigate the mechanism linking ribosome stalling, CATylation, and protein aggregation.

Main Methods:

  • Investigated nascent chain modification and aggregation under conditions of impaired Ltn1 activity.
  • Analyzed nascent chains with limited ubiquitylation potential.
  • Utilized biochemical assays to detect detergent-insoluble protein aggregates.

Main Results:

  • Demonstrated that CATylation directly mediates the formation of detergent-insoluble NC aggregates.
  • Observed CATylation and aggregation when the E3 ligase Listerin (Ltn1) was inactivated.
  • Found that inefficient Ltn1 targeting favors Rqc2-mediated CATylation and aggregation.
  • Identified a translational stalling-dependent mechanism for protein aggregation.

Conclusions:

  • CATylation serves as a specific marker for nascent chain aggregation.
  • The RQC pathway can specifically target proteins for aggregation, independent of complete degradation.
  • This study reveals a novel mechanism linking translation errors to protein aggregation.
Keywords:
<i>s. cerevisiae</i>CAT tailNEMFRQCbiochemistrycell biologylisterinltn1protein aggregationribosomerqc2ubiquitination

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