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Title | Structural and mechanistic basis of the central energy-converting methyltransferase complex of methanogenesis. |
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Journal, issue, pages | Proc Natl Acad Sci U S A, Vol. 121, Issue 14, Page e2315568121, Year 2024 |
Publish date | Apr 2, 2024 |
Authors | Iram Aziz / Kanwal Kayastha / Susann Kaltwasser / Janet Vonck / Sonja Welsch / Bonnie J Murphy / Jörg Kahnt / Di Wu / Tristan Wagner / Seigo Shima / Ulrich Ermler / |
PubMed Abstract | Methanogenic archaea inhabiting anaerobic environments play a crucial role in the global biogeochemical material cycle. The most universal electrogenic reaction of their methane-producing energy ...Methanogenic archaea inhabiting anaerobic environments play a crucial role in the global biogeochemical material cycle. The most universal electrogenic reaction of their methane-producing energy metabolism is catalyzed by -methyl-tetrahydromethanopterin: coenzyme M methyltransferase (MtrABCDEFGH), which couples the vectorial Na transport with a methyl transfer between the one-carbon carriers tetrahydromethanopterin and coenzyme M via a vitamin B derivative (cobamide) as prosthetic group. We present the 2.08 Å cryo-EM structure of Mtr(ABCDEFG) composed of the central Mtr(ABFG) stalk symmetrically flanked by three membrane-spanning MtrCDE globes. Tetraether glycolipids visible in the map fill gaps inside the multisubunit complex. Putative coenzyme M and Na were identified inside or in a side-pocket of a cytoplasmic cavity formed within MtrCDE. Its bottom marks the gate of the transmembrane pore occluded in the cryo-EM map. By integrating Alphafold2 information, functionally competent MtrA-MtrH and MtrA-MtrCDE subcomplexes could be modeled and thus the methyl-tetrahydromethanopterin demethylation and coenzyme M methylation half-reactions structurally described. Methyl-transfer-driven Na transport is proposed to be based on a strong and weak complex between MtrCDE and MtrA carrying vitamin B, the latter being placed at the entrance of the cytoplasmic MtrCDE cavity. Hypothetically, strongly attached methyl-cob(III)amide (His-on) carrying MtrA induces an inward-facing conformation, Na flux into the membrane protein center and finally coenzyme M methylation while the generated loosely attached (or detached) MtrA carrying cob(I)amide (His-off) induces an outward-facing conformation and an extracellular Na outflux. Methyl-cob(III)amide (His-on) is regenerated in the distant active site of the methyl-tetrahydromethanopterin binding MtrH implicating a large-scale shuttling movement of the vitamin B-carrying domain. |
External links | Proc Natl Acad Sci U S A / PubMed:38530900 / PubMed Central |
Methods | EM (single particle) |
Resolution | 2.08 Å |
Structure data | EMDB-18135, PDB-8q3v: |
Chemicals | ChemComp-MG:
ChemComp-JCV: ChemComp-NA: ChemComp-HOH: |
Source |
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Keywords | TRANSFERASE / methanogenesis / tetrahydromethanopterin / coenzyme M / vitamin B12 / Na+ transport |