Pre-emptive Quality Control of a Misfolded Membrane Protein by Ribosome-Driven Effects.
Curr Biol
; 30(5): 854-864.e5, 2020 03 09.
Article
in En
| MEDLINE
| ID: mdl-31956032
ABSTRACT
Cells possess multiple mechanisms that protect against the accumulation of toxic aggregation-prone proteins. Here, we identify a pre-emptive pathway that reduces synthesis of membrane proteins that have failed to properly assemble in the endoplasmic reticulum (ER). We show that loss of the ER membrane complex (EMC) or mutation of the Sec61 translocon causes reduced synthesis of misfolded forms of the yeast ABC transporter Yor1. Synthesis defects are rescued by various ribosomal mutations, as well as by reducing cellular ribosome abundance. Genetic and biochemical evidence point to a ribosome-associated quality-control pathway triggered by ribosome collisions when membrane domain insertion and/or folding fails. In support of this model, translation initiation also contributes to synthesis defects, likely by modulating ribosome abundance on the message. Examination of translation efficiency across the yeast membrane proteome revealed that polytopic membrane proteins have relatively low ribosome abundance, providing evidence for translational tuning to balance protein synthesis and folding. We propose that by modulating translation rates of poorly folded proteins, cells can pre-emptively protect themselves from potentially toxic aberrant transmembrane proteins.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Ribosomes
/
Saccharomyces cerevisiae
/
Protein Folding
/
Intracellular Membranes
/
Membrane Proteins
Language:
En
Journal:
Curr Biol
Journal subject:
BIOLOGIA
Year:
2020
Document type:
Article
Affiliation country:
United States