The conserved C-terminus of Sss1p is required to maintain the endoplasmic reticulum permeability barrier

The conserved C-terminus of Sss1p is required to maintain the endoplasmic reticulum permeability barrier

The endoplasmic reticulum (ER) is the entry point to the secretory pathway and major site of protein biogenesis. Translocation of secretory and integral membrane proteins across or into the ER membrane occurs via the evolutionarily conserved Sec61 complex, a heterotrimeric channel that comprises the...

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Bibliographic Details
Published in:The Journal of biological chemistry Vol. 295; no. 7; pp. 2125 - 2134
Main Authors: Witham, Christopher M., Dassanayake, Hasindu G., Paxman, Aleshanee L., Stevens, Kofi L.P., Baklous, Lamprini, White, Paris F., Black, Amy L., Steuart, Robert F.L., Stirling, Colin J., Schulz, Benjamin L., Mousley, Carl J.
Format: Journal Article
Language:English
Published: United States Elsevier Inc 14-02-2020
American Society for Biochemistry and Molecular Biology
Subjects:
Amino Acid Sequence - genetics
Cell Biology
endoplasmic reticulum (ER)
Endoplasmic Reticulum - genetics
endoplasmic reticulum stress (ER stress)
Endoplasmic Reticulum Stress - genetics
endoplasmic reticulum–associated protein degradation (ERAD)
gating
Multiprotein Complexes - chemistry
Multiprotein Complexes - genetics
Mutation - genetics
Permeability
Protein Biosynthesis - genetics
Protein Transport - genetics
Saccharomyces cerevisiae - genetics
Saccharomyces cerevisiae Proteins - chemistry
Saccharomyces cerevisiae Proteins - genetics
SEC Translocation Channels - chemistry
SEC Translocation Channels - genetics
Sec61 complex
Sec61p/Sec61α
Sss1p/Sec61γ
translocation
translocon gating
translocon gating
Sec61p/Sec61α
translocation
Sss1p/Sec61γ
gating
endoplasmic reticulum stress (ER stress)
Sec61 complex
endoplasmic reticulum (ER)
endoplasmic reticulum–associated protein degradation (ERAD)
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Summary:The endoplasmic reticulum (ER) is the entry point to the secretory pathway and major site of protein biogenesis. Translocation of secretory and integral membrane proteins across or into the ER membrane occurs via the evolutionarily conserved Sec61 complex, a heterotrimeric channel that comprises the Sec61p/Sec61α, Sss1p/Sec61γ, and Sbh1p/Sec61β subunits. In addition to forming a protein-conducting channel, the Sec61 complex also functions to maintain the ER permeability barrier, preventing the mass free flow of essential ER-enriched molecules and ions. Loss in Sec61 integrity is detrimental and implicated in the progression of disease. The Sss1p/Sec61γ C terminus is juxtaposed to the key gating module of Sec61p/Sec61α, and we hypothesize it is important for gating the ER translocon. The ER stress response was found to be constitutively induced in two temperature-sensitive sss1 mutants (sss1ts) that are still proficient to conduct ER translocation. A screen to identify intergenic mutations that allow for sss1ts cells to grow at 37 °C suggests the ER permeability barrier to be compromised in these mutants. We propose the extreme C terminus of Sss1p/Sec61γ is an essential component of the gating module of the ER translocase and is required to maintain the ER permeability barrier.
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Present address: Office of the Vice Chancellor, Flinders University, Sturt Rd., Bedford Park, SA 5042, Australia.
Edited by Peter Cresswell
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.RA119.010378