An evolving view of the eukaryotic oligosaccharyltransferase

Kelleher, Daniel J.; Gilmore, Reid

doi:10.1093/glycob/cwj066

Cited by 477 publications

(484 citation statements)

References 155 publications

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“…However, prokaryotic protein N-glycosylation is simpler and occurs post-translationally. In contrast, most N-glycosylation in eukaryotes is co-translational 14 . Eukaryotes have evolved a sophisticated machinery to cope with this complexity.…”

Section: Introductionmentioning

confidence: 96%

The atomic structure of a eukaryotic oligosaccharyltransferase complex

Bai

Wang

Zhao

et al. 2018

Nature

101

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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Section: Introductionmentioning

confidence: 96%

The atomic structure of a eukaryotic oligosaccharyltransferase complex

Bai

Wang

Zhao

et al. 2018

Nature

101

131

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“…TUSC3, the Ost3 Saccharomyces cerevisiae human ortholog, was initially identified as a 34 kD subunit in the yeast oligosaccharyltransferase complex (Kelleher and Gilmore 2006). The TUSC3 gene, composed of 11 exons spanning~224 Kbp of the genomic DNA on chromosome 8p22, encodes a predicted 348-amino-acid protein with five potential transmembrane domains.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, OTase is an oligomeric membrane-protein complex that mediates the transfer of a preassembled highmannose oligosaccharide onto asparagine residues of nascent polypeptides entering the lumen of the endoplasmic reticulum. Two mammalian OTase complexes composed of seven proteins differ by the presence of TUSC3 or IAP proteins (Kelleher and Gilmore 2006). TUSC3 appears ubiquitously expressed with greater expression in the fetal brain (Molinari et al 2008) and interacts with the alpha isoform of the protein phosphatase 1 (PPPC1A; OMIM176875) catalytic subunit, which is involved in the modulation of synaptic plasticity, and in memory and learning processes in mice (Garshasbi et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Homozygous Truncating Intragenic Duplication in TUSC3 Responsible for Rare Autosomal Recessive Nonsyndromic Intellectual Disability with No Clinical or Biochemical Metabolic Markers

Chehadeh

Bonnet²,

Callier

et al. 2014

JIMD Reports

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Intellectual disability (ID), which affects around 2-3% of the general population, is classically divided into syndromic and nonsyndromic forms, with several modes of inheritance. Nonsyndromic autosomal recessive ID (NS-ARID) appears extremely heterogeneous with numerous genes identified to date, including inborn errors of metabolism. The TUSC3 gene encodes a subunit of the endoplasmic reticulum (ER)-bound oligosaccharyltransferase complex, which mediates a key step of N-glycosylation. To date, only five families with NS-ARID and TUSC3 mutations or rearrangements have been reported in the literature. All patients had speech delay, moderate-to-severe ID, and moderate facial dysmorphism. Microcephaly was noted in one third of patients, as was short stature. No patients had congenital malformation except one patient with unilateral cryptorchidism. Glycosylation analyses of patients' fibroblasts showed normal N-glycan synthesis and transfer. We present a review of the 19 patients previously described in the literature and report on a sixth consanguineous family including two affected sibs, with intellectual disability, unspecific dysmorphic features, and no additional malformations identified by high-resolution array-CGH. A homozygous truncating intragenic duplication of the TUSC3 gene leading to an aberrant transcript was detected in two siblings. This observation, which is the first reported case of TUSC3 homozygous duplication, confirms the implication of TUSC3 in NS-ARID and the power of the high-resolution array-CGH in identifying intragenic rearrangements of genes implicated in nonsyndromic ID and rare diseases.

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“…[1][2][3] N-glycosylation is catalyzed in the lumen of the endoplasmic reticulum (ER) by the multiprotein complex oligosaccharyltransferase (OTase). 4 OTase physically associates with ribosomes bound at the translocon 5 and transfers an oligosaccharide (typically Glucose 3 Mannose 9 N-acetylglucosamine 2 ) from a dolicholpyrophosphate donor to selected Asn side-chains in nascent polypeptide substrates. Glycosylation efficiency of Asn residues is greatly enhanced if they are present in glycosylation ''sequons'' (Asn-Xaa-Thr/ Ser; Xaa=Pro), 4 although Asn not in sequons can in rare cases also be glycosylated.…”

Section: Introductionmentioning

confidence: 99%

“…4 OTase physically associates with ribosomes bound at the translocon 5 and transfers an oligosaccharide (typically Glucose 3 Mannose 9 N-acetylglucosamine 2 ) from a dolicholpyrophosphate donor to selected Asn side-chains in nascent polypeptide substrates. Glycosylation efficiency of Asn residues is greatly enhanced if they are present in glycosylation ''sequons'' (Asn-Xaa-Thr/ Ser; Xaa=Pro), 4 although Asn not in sequons can in rare cases also be glycosylated. 6 The presence of Nglycans on proteins assists productive folding in the ER intrinsically by virtue of their bulky hydrophilic nature, and also indirectly by specifically recruiting molecular chaperones.…”

Section: Introductionmentioning

confidence: 99%

Polypeptide binding specificities of Saccharomyces cerevisiae oligosaccharyltransferase accessory proteins Ost3p and Ost6p

et al. 2011

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Asparagine-linked glycosylation is a common and vital co-and post-translocational modification of diverse secretory and membrane proteins in eukaryotes that is catalyzed by the multiprotein complex oligosaccharyltransferase (OTase). Two isoforms of OTase are present in Saccharomyces cerevisiae, defined by the presence of either of the homologous proteins Ost3p or Ost6p, which possess different protein substrate specificities at the level of individual glycosylation sites. Here we present in vitro characterization of the polypeptide binding activity of these two subunits of the yeast enzyme, and show that the peptide-binding grooves in these proteins can transiently bind stretches of polypeptide with amino acid characteristics complementary to the characteristics of the grooves. We show that Ost6p, which has a peptide-binding groove with a strongly hydrophobic base lined by neutral and basic residues, binds peptides enriched in hydrophobic and acidic amino acids. Further, by introducing basic residues in place of the wild type neutral residues lining the peptide-binding groove of Ost3p, we engineer binding of a hydrophobic and acidic peptide. Our data supports a model of Ost3/6p function in which they transiently bind stretches of nascent polypeptide substrate to inhibit protein folding, thereby increasing glycosylation efficiency at nearby asparagine residues.

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An evolving view of the eukaryotic oligosaccharyltransferase

Cited by 477 publications

References 155 publications

The atomic structure of a eukaryotic oligosaccharyltransferase complex

The atomic structure of a eukaryotic oligosaccharyltransferase complex

Homozygous Truncating Intragenic Duplication in TUSC3 Responsible for Rare Autosomal Recessive Nonsyndromic Intellectual Disability with No Clinical or Biochemical Metabolic Markers

Polypeptide binding specificities of Saccharomyces cerevisiae oligosaccharyltransferase accessory proteins Ost3p and Ost6p

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