Protein O-mannosyltransferases associate with the translocon to modify translocating polypeptide chains

Loibl, Martin, Wunderle, Lina, Hutzler, Johannes, Schulz, Benjamin L., Aebi, Markus and Strahl, Sabine (2014) Protein O-mannosyltransferases associate with the translocon to modify translocating polypeptide chains. Journal of Biological Chemistry, 289 12: 8599-8611. doi:10.1074/jbc.M113.543116


Author Loibl, Martin
Wunderle, Lina
Hutzler, Johannes
Schulz, Benjamin L.
Aebi, Markus
Strahl, Sabine
Title Protein O-mannosyltransferases associate with the translocon to modify translocating polypeptide chains
Journal name Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
1083-351X
Publication date 2014-03-21
Year available 2014
Sub-type Article (original research)
DOI 10.1074/jbc.M113.543116
Open Access Status DOI
Volume 289
Issue 12
Start page 8599
End page 8611
Total pages 13
Place of publication Bethesda, MD United States
Publisher American Society for Biochemistry and Molecular Biology
Language eng
Subject 1303 Specialist Studies in Education
1307 Cell Biology
1312 Molecular Biology
Abstract O-Mannosylation and N-glycosylation are essential protein modifications that are initiated in the endoplasmic reticulum (ER). Protein translocation across the ER membrane and N-glycosylation are highly coordinated processes that take place at the translocon-oligosaccharyltransferase (OST) complex. In analogy, it was assumed that protein O-mannosyltransferases (PMTs) also act at the translocon, however, in recent years it turned out that prolonged ER residence allows O-mannosylation of un-/misfolded proteins or slow folding intermediates by Pmt1-Pmt2 complexes. Here, we reinvestigate protein O-mannosylation in the context of protein translocation. We demonstrate the association of Pmt1-Pmt2 with the OST, the trimeric Sec61, and the tetrameric Sec63 complex in vivo by co-immunoprecipitation. The coordinated interplay between PMT sand OST in vivo is further shown by a comprehensive mass spectrometry-based analysis of N-glycosylation site occupancy in pmtΔ mutants. In addition, we established a microsomal translation/translocation/O- mannosylation system. Using the serine/threonine-rich cell wall protein Ccw5 as a model, we show that PMTs efficiently mannosylate proteins during their translocation into microsomes. This in vitro system will help to unravel mechanistic differences between co- and post-translocational O-mannosylation.
Keyword Biochemistry & Molecular Biology
Biochemistry & Molecular Biology
BIOCHEMISTRY & MOLECULAR BIOLOGY
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID SFB638
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Non HERDC
School of Chemistry and Molecular Biosciences
 
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