Structural characterisation of the fungal Pmt4 homodimer
Protein O-mannosyltransferases (PMTs) are conserved endoplasmic reticulum membrane-embedded enzymes responsible for the transfer of mannose from dolichol phosphate-mannose (Dol-P-Man) to serine/threonine-rich protein substrates or unfolded proteins. PMTs from three subfamilies form obligate dimers w...
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| Hauptverfasser: | , , , , , , , , , , , , , |
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| Dokumenttyp: | Article (Journal) |
| Sprache: | Englisch |
| Veröffentlicht: |
14 December 2025
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| In: |
Nature Communications
Year: 2025, Jahrgang: 16, Pages: 1-14 |
| ISSN: | 2041-1723 |
| DOI: | 10.1038/s41467-025-67412-1 |
| Online-Zugang: | Verlag, kostenfrei, Volltext: https://doi.org/10.1038/s41467-025-67412-1 Verlag, kostenfrei, Volltext: https://www.nature.com/articles/s41467-025-67412-1 |
| Verfasserangaben: | Melanie A. McDowell, Klemens Wild, Francesco Fiorentino, Daniela Bausewein, Anke Metschies, Antonella Chiapparino, Yvonne Hackmann, Florestan L. Bilsing, David Brenske, Sofia Mortensen, Di Wu, Carol V. Robinson, Sabine Strahl & Irmgard Sinning |
| Zusammenfassung: | Protein O-mannosyltransferases (PMTs) are conserved endoplasmic reticulum membrane-embedded enzymes responsible for the transfer of mannose from dolichol phosphate-mannose (Dol-P-Man) to serine/threonine-rich protein substrates or unfolded proteins. PMTs from three subfamilies form obligate dimers with different substrate specificities and require the concerted action of their transmembrane domains (TMDs) and a luminal MIR domain for catalysis. Here, we present structures, native mass spectrometry, and structure-based mutagenesis of the fungal Pmt4 homodimer. The core fold of the TMDs and MIR domain is conserved with the Pmt1-Pmt2 heterodimer, indicating a shared catalytic mechanism. Distinct from Pmt4, the MIR domain interacts in cis with the TMDs of the same subunit and has a β-hairpin insertion required for O-mannosylation of substrates. We further identify a cytosolic binding site for substrate Dol-P-Man within the Pmt4 TMDs, which is conserved amongst PMTs and important for in vivo activity. Thus, we provide a framework to understand the substrate specificity and regulation of the Pmt4 homodimer. |
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| Beschreibung: | Veröffentlicht: 14. Dezember 2025 Gesehen am 11.02.2026 |
| Beschreibung: | Online Resource |
| ISSN: | 2041-1723 |
| DOI: | 10.1038/s41467-025-67412-1 |