N-linked glycosylation and homeostasis of the endoplasmic reticulum

Cherepanova, Natalia A.; Shrimal, Shiteshu; Gilmore, Reid

doi:10.1016/j.ceb.2016.03.021

Cited by 214 publications

(233 citation statements)

References 65 publications

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“…A similar role for intramembrane proteolysis in the abundance control of glycosyltransferases has been described previously for the Golgi-resident SPP-like protease 3 (SPPL3) (Voss et al, 2014). This indicates that intramembrane proteolysis plays a global role in the control of protein glycosylation, which has a wide range of important functions such as controlling enzyme activity, protein-protein interactions and protein stability (Cherepanova et al, 2016).…”

Section: Discussionsupporting

confidence: 74%

“…We identified several subunits of the oligosacharyltransferase (OST) complex as substrates for the RHBDL4-dependent ERAD pathway. The OST complex catalyzes the transfer of a preassembled oligosaccharide from a lipid-linked oligosaccharide donor onto the asparagine residue of glycosylation acceptor sites known as sequons (N-X-S/T; X¹P) in newly synthesized proteins (Cherepanova et al, 2016). Insects, vertebrates and plants assemble two OST complexes that are composed of a complex-specific catalytic subunit (STT3A or STT3B), a set of shared subunits (RPN1, RPN2, DDOST, DAD1, OST4 and TMEM258 in mammalian cells) as well as complex-specific accessory subunits that only assemble with STT3A (DC2 and KCP2) or STT3B (MagT1 or TUSC3) (Kelleher et al, 2003;Roboti and High, 2012;Shibatani et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Intramembrane protease RHBDL4 cleaves oligosaccharyltransferase subunits to target them for ER-associated degradation

Knopf

Landscheidt

Pegg

et al. 2019

Preprint

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The Endoplasmic Reticulum (ER)-resident intramembrane rhomboid protease RHBDL4 generates metastable protein fragments and together with the ER-associated degradation (ERAD) machinery provides a clearance mechanism for aberrant and surplus proteins.However, the endogenous substrate spectrum and with that the role of RHBDL4 in physiological ERAD is mainly unknown. Here, we use quantitative proteomics to identify physiological RHBDL4 substrates. This revealed oligosacharyltransferase (OST) complex subunits such as the catalytic active subunit STT3A as substrates for the RHBDL4dependent ERAD pathway. RHBDL4-catalyzed cleavage inactivates OST subunits by triggering dislocation into the cytoplasm and subsequent proteasomal degradation. RHBDL4catalyzed cleavage is enhanced by positive charged transmembrane residues, which are recognized by a putative negative-charged docking site at the rhomboid active site gate.RHBDL4 controls the abundance and activity of OST, suggesting a novel link between the ERAD machinery and glycosylation tuning in the ER. AbbreviationsERAD, ER-associated degradation; OST, oligosacharyltransferase; TM, transmembrane; UIM, ubiquitin-interacting motif.

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Section: Discussionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Intramembrane protease RHBDL4 cleaves oligosaccharyltransferase subunits to target them for ER-associated degradation

Knopf

Landscheidt

Pegg

et al. 2019

Preprint

View full text Add to dashboard Cite

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“…Saccharomyces cerevisiae has two OST isoforms each with eight membrane proteins: the isoforms contain either Ost3 or Ost6 plus seven shared components: Ost1, 2, 4, and 5; Stt3; Wbp1; and Swp1 15 . All these subunits have homologs in the metazoan OST 2 : ribophorin I corresponds to the yeast Ost1, DAD1 to Ost2, N33/MagT1 or DC2/KCP2 to Ost3/6, OST4 to Ost4, TMEM258 to Ost5, OST48 to Wbp1, STT3A/STT3B to Stt3, and ribophorin II to Swp1 16 . Crystal structures of the Ost6 lumenal domain revealed a thioredoxin fold (TRX) 17,18 .…”

Section: Introductionmentioning

confidence: 99%

The atomic structure of a eukaryotic oligosaccharyltransferase complex

Bai

Wang

Zhao

et al. 2018

Nature

102

131

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SUMMARY N-glycosylation is a ubiquitous modification of eukaryotic secretory and membrane-bound proteins; about 90% of glycoproteins are N-glycosylated. The reaction is catalyzed by an eight-protein oligosaccharyltransferase complex, OST, embedded in the ER membrane. Our understanding of eukaryotic protein N-glycosylation has been limited due to the lack of high-resolution structures. Here we report a 3.5-Å resolution cryo-EM structure of the Saccharomyces cerevisiae OST, revealing the structures of Ost1–5, Stt3, Wbp1, and Swp1. We found that seven phospholipids mediate many of the inter-subunit interactions, and an Stt3 N-glycan mediates interaction with Wbp1 and Swp1 in the lumen. Ost3 was found to mediate the OST-Sec61 translocon interface, funneling the acceptor peptide towards the OST catalytic site as the nascent peptide emerges from the translocon. The structure provides novel insights into co-translational protein N-glycosylation and may facilitate the development of small-molecule inhibitors targeting this process.

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“…One of two isoforms of the oligosaccharyltransferase (OST), STT3A or STT3B, transfers a pre-formed glycan structure onto the asparagine residue11. Upon glucose trimming, the oligosaccharide serves as a tag for ER chaperones to detect the folding status of proteins and ultimately ensures that export is restricted only to properly folded glycoproteins12.…”

mentioning

confidence: 99%

Missense mutations near the N-glycosylation site of the A2 domain lead to various intracellular trafficking defects in coagulation factor VIII

Wei

Zheng

Zhu

et al. 2017

Sci Rep

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Missense mutation is the most common mutation type in hemophilia. However, the majority of missense mutations remain uncharacterized. Here we characterize how hemophilia mutations near the unused N-glycosylation site of the A2 domain (N582) of FVIII affect protein conformation and intracellular trafficking. N582 is located in the middle of a short 310-helical turn (D580-S584), in which most amino acids have multiple hemophilia mutations. All 14 missense mutations found in this 310-helix reduced secretion levels of the A2 domain and full-length FVIII. Secreted mutants have decreased activities relative to WT FVIII. Selected mutations also lead to partial glycosylation of N582, suggesting that rapid folding of local conformation prevents glycosylation of this site in wild-type FVIII. Protease sensitivity, stability and degradation of the A2 domain vary among mutants, and between non-glycosylated and glycosylated species of the same mutant. Most of the mutants interact with the ER chaperone BiP, while only mutants with aberrant glycosylation interact with calreticulin. Our results show that the short 310-helix from D580 to S584 is critical for proper biogenesis of the A2 domain and FVIII, and reveal a range of molecular mechanisms by which FVIII missense mutations lead to moderate to severe hemophilia A.

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N-linked glycosylation and homeostasis of the endoplasmic reticulum

Cited by 214 publications

References 65 publications

Intramembrane protease RHBDL4 cleaves oligosaccharyltransferase subunits to target them for ER-associated degradation

Intramembrane protease RHBDL4 cleaves oligosaccharyltransferase subunits to target them for ER-associated degradation

The atomic structure of a eukaryotic oligosaccharyltransferase complex

Missense mutations near the N-glycosylation site of the A2 domain lead to various intracellular trafficking defects in coagulation factor VIII

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