7NPA

Crystal structure of the Coenzyme F420-dependent sulfite reductase from Methanothermococcus thermolithotrophicus at 1.55-A resolution

Summary for 7NPA

• Entry DOI: 10.2210/pdb7npa/pdb
• Descriptor: Coenzyme F420-dependent sulfite reductase, LITHIUM ION, DI(HYDROXYETHYL)ETHER, ... (13 entities in total)
• Functional Keywords: sulfite detoxification, sulfur metabolism, sulfide, hydrogenotrophic methanogens, iron-sulfur cluster, sulfite-reductase evolution, sulfite/nitrite reductase, siroheme, flavin, oxidoreductase, ferredoxin, f420, thermophile
• Biological source: Methanothermococcus thermolithotrophicus DSM 2095
• Total number of polymer chains: 16
• Total formula weight: 1184790.82

Authors

Jespersen, M.,Wagner, T. (deposition date: 2021-02-26, release date: 2022-03-23, Last modification date: 2024-02-07)

Primary citation

Jespersen, M.,Pierik, A.J.,Wagner, T.
Structures of the sulfite detoxifying F 420 -dependent enzyme from Methanococcales.
Nat.Chem.Biol., 2023

PubMed Abstract: Methanogenic archaea are main actors in the carbon cycle but are sensitive to reactive sulfite. Some methanogens use a sulfite detoxification system that combines an FH-oxidase with a sulfite reductase, both of which are proposed precursors of modern enzymes. Here, we present snapshots of this coupled system, named coenzyme F-dependent sulfite reductase (Group I Fsr), obtained from two marine methanogens. Fsr organizes as a homotetramer, harboring an intertwined six-[4Fe-4S] cluster relay characterized by spectroscopy. The wire, spanning 5.4 nm, electronically connects the flavin to the siroheme center. Despite a structural architecture similar to dissimilatory sulfite reductases, Fsr shows a siroheme coordination and a reaction mechanism identical to assimilatory sulfite reductases. Accordingly, the reaction of Fsr is unidirectional, reducing sulfite or nitrite with FH. Our results provide structural insights into this unique fusion, in which a primitive sulfite reductase turns a poison into an elementary block of life.

PubMed: 36658338
DOI: 10.1038/s41589-022-01232-y

Experimental method

X-RAY DIFFRACTION (1.55 Å)