National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM126982
米国
引用
ジャーナル: Proc Natl Acad Sci U S A / 年: 2024 タイトル: Capturing a methanogenic carbon monoxide dehydrogenase/acetyl-CoA synthase complex via cryogenic electron microscopy. 著者: Alison Biester / David A Grahame / Catherine L Drennan / 要旨: Approximately two-thirds of the estimated one-billion metric tons of methane produced annually by methanogens is derived from the cleavage of acetate. Acetate is broken down by a Ni-Fe-S-containing A- ...Approximately two-thirds of the estimated one-billion metric tons of methane produced annually by methanogens is derived from the cleavage of acetate. Acetate is broken down by a Ni-Fe-S-containing A-cluster within the enzyme acetyl-CoA synthase (ACS) to carbon monoxide (CO) and a methyl group (CH). The methyl group ultimately forms the greenhouse gas methane, whereas CO is converted to the greenhouse gas carbon dioxide (CO) by a Ni-Fe-S-containing C-cluster within the enzyme carbon monoxide dehydrogenase (CODH). Although structures have been solved of CODH/ACS from acetogens, which use these enzymes to make acetate from CO, no structure of a CODH/ACS from a methanogen has been reported. In this work, we use cryo-electron microscopy to reveal the structure of a methanogenic CODH and CODH/ACS from (CODH/ACS). We find that the N-terminal domain of acetogenic ACS, which is missing in all methanogens, is replaced by a domain of CODH. This CODH domain provides a channel for CO to travel between the two catalytic Ni-Fe-S clusters. It generates the binding surface for ACS and creates a remarkably similar CO alcove above the A-cluster using residues from CODH rather than ACS. Comparison of our CODH/ACS structure with our CODH structure reveals a molecular mechanism to restrict gas flow from the CO channel when ACS departs, preventing CO escape into the cell. Overall, these long-awaited structures of a methanogenic CODH/ACS reveal striking functional similarities to their acetogenic counterparts despite a substantial difference in domain organization.
Chain - Source name: AlphaFold / Chain - Initial model type: in silico model
ソフトウェア
名称: Coot (ver. 0.9.8.92)
詳細
Initial model was generated using AlphaFold, fit to the map using ChimeraX, followed by rigid body fitting in phenix, and finally iterative real space refinement in coot and phenix.
精密化
空間: REAL / 温度因子: 90.5204 / 当てはまり具合の基準: Correlation coefficient
得られたモデル
PDB-9c0q: Carbon monoxide dehydrogenase (CODH) from Methanosarcina thermophila, specimen prepared on blot plunger