6P25

Structure of S. cerevisiae protein O-mannosyltransferase Pmt1-Pmt2 complex bound to the sugar donor and a peptide acceptor

Summary for 6P25

• Entry DOI: 10.2210/pdb6p25/pdb
• EMDB information: 20236 20237 20240
• Descriptor: Dolichyl-phosphate-mannose--protein mannosyltransferase 1, Dolichyl-phosphate-mannose--protein mannosyltransferase 2, acceptor peptide, ... (6 entities in total)
• Functional Keywords: complex, transferase, glycosylation
• Biological source: Saccharomyces cerevisiae W303 (yeast); More
• Total number of polymer chains: 3
• Total formula weight: 183568.63

Authors

Bai, L.,Li, H. (deposition date: 2019-05-21, release date: 2019-07-10, Last modification date: 2024-10-30)

Primary citation

Bai, L.,Kovach, A.,You, Q.,Kenny, A.,Li, H.
Structure of the eukaryotic protein O-mannosyltransferase Pmt1-Pmt2 complex.
Nat.Struct.Mol.Biol., 26:704-711, 2019

PubMed Abstract: In eukaryotes, a nascent peptide entering the endoplasmic reticulum (ER) is scanned by two Sec61 translocon-associated large membrane machines for protein N-glycosylation and protein O-mannosylation, respectively. While the structure of the eight-protein oligosaccharyltransferase complex has been determined recently, the structures of mannosyltransferases of the PMT family, which are an integral part of ER protein homeostasis, are still unknown. Here we report cryo-EM structures of the Saccharomyces cerevisiae Pmt1-Pmt2 complex bound to a donor and an acceptor peptide at 3.2-Å resolution, showing that each subunit contains 11 transmembrane helices and a lumenal β-trefoil fold termed the MIR domain. The structures reveal the substrate recognition model and confirm an inverting mannosyl-transferring reaction mechanism by the enzyme complex. Furthermore, we found that the transmembrane domains of Pmt1 and Pmt2 share a structural fold with the catalytic subunits of oligosaccharyltransferases, confirming a previously proposed evolutionary relationship between protein O-mannosylation and protein N-glycosylation.

PubMed: 31285605
DOI: 10.1038/s41594-019-0262-6

Experimental method

ELECTRON MICROSCOPY (3.2 Å)