Glycosyl transferase family 39/83 / Glycosyltransferase 39-like / Protein O-mannosyl-transferase, C-terminal four TM domain / Dolichyl-phosphate-mannose-protein mannosyltransferase / C-terminal four TMM region of protein-O-mannosyltransferase / MIR motif / MIR domain / MIR domain profile. / Domain in ryanodine and inositol trisphosphate receptors and protein O-mannosyltransferases / Mir domain superfamily 類似検索 - ドメイン・相同性
ACETATE ION / Dolichyl-phosphate-mannose--protein mannosyltransferase 類似検索 - 構成要素
ジャーナル: Nat Commun / 年: 2025 タイトル: Structural characterisation of the fungal Pmt4 homodimer. 著者: Melanie A McDowell / Klemens Wild / Francesco Fiorentino / Daniela Bausewein / Anke Metschies / Antonella Chiapparino / Yvonne Hackmann / Florestan L Bilsing / David Brenske / Sofia Mortensen ...著者: 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 / 要旨: 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 ...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.