The Metastable XBP1u transmembrane domain defines determinants for intramembrane proteolysis by signal peptide peptidase
Summary - Unspliced XBP1 mRNA encodes XBP1u, the transcriptionally inert variant of the unfolded protein response (UPR) transcription factor XBP1s. XBP1u targets its mRNA-ribosome-nascent-chain-complex to the endoplasmic reticulum (ER) to facilitate UPR activation and prevents overactivation. Yet, i...
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| Main Authors: | , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
March 12, 2019
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| In: |
Cell reports
Year: 2019, Volume: 26, Issue: 11, Pages: 3087-3099, e1-e11 |
| ISSN: | 2211-1247 |
| DOI: | 10.1016/j.celrep.2019.02.057 |
| Online Access: | Verlag, Volltext: https://doi.org/10.1016/j.celrep.2019.02.057 Verlag, Volltext: http://www.sciencedirect.com/science/article/pii/S2211124719302360 
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| Author Notes: | Sara Suna Yücel, Walter Stelzer, Alessandra Lorenzoni, Manfred Wozny, Dieter Langosch, and Marius K. Lemberg |
| Summary: | Summary - Unspliced XBP1 mRNA encodes XBP1u, the transcriptionally inert variant of the unfolded protein response (UPR) transcription factor XBP1s. XBP1u targets its mRNA-ribosome-nascent-chain-complex to the endoplasmic reticulum (ER) to facilitate UPR activation and prevents overactivation. Yet, its membrane association is controversial. Here, we use cell-free translocation and cellular assays to define a moderately hydrophobic stretch in XBP1u that is sufficient to mediate insertion into the ER membrane. Mutagenesis of this transmembrane (TM) region reveals residues that facilitate XBP1u turnover by an ER-associated degradation route that is dependent on signal peptide peptidase (SPP). Furthermore, the impact of these mutations on TM helix dynamics was assessed by residue-specific amide exchange kinetics, evaluated by a semi-automated algorithm. Based on our results, we suggest that SPP-catalyzed intramembrane proteolysis of TM helices is not only determined by their conformational flexibility, but also by side-chain interactions near the scissile peptide bond with the enzyme’s active site. |
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| Item Description: | Gesehen am 24.04.2019 |
| Physical Description: | Online Resource |
| ISSN: | 2211-1247 |
| DOI: | 10.1016/j.celrep.2019.02.057 |