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Cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling

The folding of newly synthesized proteins to the native state is a major challenge within the crowded cellular environment, as non-productive interactions can lead to misfolding, aggregation and degradation1. Cells cope with this challenge by coupling synthesis with polypeptide folding and by using...

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Autores principales: Shiber, Ayala, Döring, Kristina, Friedrich, Ulrike, Klann, Kevin, Merker, Dorina, Zedan, Mostafa, Tippmann, Frank, Kramer, Günter, Bukau, Bernd
Formato: Online Artículo Texto
Lenguaje:English
Publicado: 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6372068/
https://www.ncbi.nlm.nih.gov/pubmed/30158700
http://dx.doi.org/10.1038/s41586-018-0462-y
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author Shiber, Ayala
Döring, Kristina
Friedrich, Ulrike
Klann, Kevin
Merker, Dorina
Zedan, Mostafa
Tippmann, Frank
Kramer, Günter
Bukau, Bernd
author_facet Shiber, Ayala
Döring, Kristina
Friedrich, Ulrike
Klann, Kevin
Merker, Dorina
Zedan, Mostafa
Tippmann, Frank
Kramer, Günter
Bukau, Bernd
author_sort Shiber, Ayala
collection PubMed
description The folding of newly synthesized proteins to the native state is a major challenge within the crowded cellular environment, as non-productive interactions can lead to misfolding, aggregation and degradation1. Cells cope with this challenge by coupling synthesis with polypeptide folding and by using molecular chaperones to safeguard folding cotranslationally2. However, although most of the cellular proteome forms oligomeric assemblies3, little is known about the final step of folding: the assembly of polypeptides into complexes. In prokaryotes, a proof-of-concept study showed that the assembly of heterodimeric luciferase is an organized cotranslational process that is facilitated by spatially confined translation of the subunits encoded on a polycistronic mRNA4. In eukaryotes, however, fundamental differences—such as the rarity of polycistronic mRNAs and different chaperone constellations—raise the question of whether assembly is also coordinated with translation. Here we provide a systematic and mechanistic analysis of the assembly of protein complexes in eukaryotes using ribosome profiling. We determined the in vivo interactions of the nascent subunits from twelve hetero-oligomeric protein complexes of Saccharomyces cerevisiae at near-residue resolution. We find nine complexes assemble cotranslationally; the three complexes that do not show cotranslational interactions are regulated by dedicated assembly chaperones5–7. Cotranslational assembly often occurs uni-directionally, with one fully synthesized subunit engaging its nascent partner subunit, thereby counteracting its propensity for aggregation. The onset of cotranslational subunit association coincides directly with the full exposure of the nascent interaction domain at the ribosomal tunnel exit. The ribosome-associated Hsp70 chaperone Ssb8 is coordinated with assembly. Ssb transiently engages partially synthesized interaction domains and then dissociates before the onset of partner subunit association, presumably to prevent premature assembly interactions. Our study shows that cotranslational subunit association is a prevalent mechanism for the assembly of hetero-oligomers in yeast and indicates that translation, folding and assembly of protein complexes are integrated processes in eukaryotes.
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spelling pubmed-63720682019-02-28 Cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling Shiber, Ayala Döring, Kristina Friedrich, Ulrike Klann, Kevin Merker, Dorina Zedan, Mostafa Tippmann, Frank Kramer, Günter Bukau, Bernd Nature Article The folding of newly synthesized proteins to the native state is a major challenge within the crowded cellular environment, as non-productive interactions can lead to misfolding, aggregation and degradation1. Cells cope with this challenge by coupling synthesis with polypeptide folding and by using molecular chaperones to safeguard folding cotranslationally2. However, although most of the cellular proteome forms oligomeric assemblies3, little is known about the final step of folding: the assembly of polypeptides into complexes. In prokaryotes, a proof-of-concept study showed that the assembly of heterodimeric luciferase is an organized cotranslational process that is facilitated by spatially confined translation of the subunits encoded on a polycistronic mRNA4. In eukaryotes, however, fundamental differences—such as the rarity of polycistronic mRNAs and different chaperone constellations—raise the question of whether assembly is also coordinated with translation. Here we provide a systematic and mechanistic analysis of the assembly of protein complexes in eukaryotes using ribosome profiling. We determined the in vivo interactions of the nascent subunits from twelve hetero-oligomeric protein complexes of Saccharomyces cerevisiae at near-residue resolution. We find nine complexes assemble cotranslationally; the three complexes that do not show cotranslational interactions are regulated by dedicated assembly chaperones5–7. Cotranslational assembly often occurs uni-directionally, with one fully synthesized subunit engaging its nascent partner subunit, thereby counteracting its propensity for aggregation. The onset of cotranslational subunit association coincides directly with the full exposure of the nascent interaction domain at the ribosomal tunnel exit. The ribosome-associated Hsp70 chaperone Ssb8 is coordinated with assembly. Ssb transiently engages partially synthesized interaction domains and then dissociates before the onset of partner subunit association, presumably to prevent premature assembly interactions. Our study shows that cotranslational subunit association is a prevalent mechanism for the assembly of hetero-oligomers in yeast and indicates that translation, folding and assembly of protein complexes are integrated processes in eukaryotes. 2018-08-29 2018-09 /pmc/articles/PMC6372068/ /pubmed/30158700 http://dx.doi.org/10.1038/s41586-018-0462-y Text en Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:http://www.nature.com/authors/editorial_policies/license.html#terms
spellingShingle Article
Shiber, Ayala
Döring, Kristina
Friedrich, Ulrike
Klann, Kevin
Merker, Dorina
Zedan, Mostafa
Tippmann, Frank
Kramer, Günter
Bukau, Bernd
Cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling
title Cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling
title_full Cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling
title_fullStr Cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling
title_full_unstemmed Cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling
title_short Cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling
title_sort cotranslational assembly of protein complexes in eukaryotes revealed by ribosome profiling
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6372068/
https://www.ncbi.nlm.nih.gov/pubmed/30158700
http://dx.doi.org/10.1038/s41586-018-0462-y
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