Structure of the Methanosarcina mazei Mtr complex bound to the oxygen-stress responsive small protein MtrI.

ABSTRACT: Methanogenic archaea emit ~1 Gt of methane annually, impacting global carbon cycling and climate. Central to their energy metabolism is a membrane-bound, sodium-translocating methyltransferase complex: the N⁵-tetrahydromethanopterin:CoM-S-methyltransferase (Mtr). It couples methyl transfer between two methanogen-specific cofactors with sodium ion transport across the membrane, forming the only energy-conserving step in hydrogenotrophic methanogenesis. Here, we present a 2.1 Å single-particle cryo-EM structure of the Mtr complex from Methanosarcina mazei. The structure reveals the organization of all catalytic subunits, embedded archaeal lipids and the sodium-binding site. Most strikingly, we discover MtrI, a previously unannotated small open-reading frame encoded protein ( < 100 aa) found

SUBMITTER: Reif-Trauttmansdorff T 

PROVIDER: S-EPMC12774963 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature