Structures of the sulfite detoxifying F420-dependent enzyme from Methanococcales.
Nat Chem Biol
; 19(6): 695-702, 2023 06.
Article
em En
| MEDLINE
| ID: mdl-36658338
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 F420H2-oxidase with a sulfite reductase, both of which are proposed precursors of modern enzymes. Here, we present snapshots of this coupled system, named coenzyme F420-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 F420H2. Our results provide structural insights into this unique fusion, in which a primitive sulfite reductase turns a poison into an elementary block of life.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Methanococcales
/
Euryarchaeota
Idioma:
En
Revista:
Nat Chem Biol
Ano de publicação:
2023
Tipo de documento:
Article