Structure of a dioxygen reduction enzyme from Desulfovibrio gigas

Desulfovibrio gigas is a strict anaerobe that contains a well-characterized metabolic pathway that enables it to survive transient contacts with oxyge n. The terminal enzyme in this pathway, rubredoxin:oxygen oxidoreductase (R OO) reduces oxygen to water in a direct and safe way. The 2.5 Angstrom reso lution crystal structure of ROO shows that each monomer of this homodimeric enzyme consists of a novel combination of two domains, a flavodoxin-like d omain and a Zn-beta -lactamase-like domain that contains a di-iron center f or dioxygen reduction. This is the first structure of a member of a superfa mily of enzymes widespread in strict and facultative anaerobes, indicating its broad physiological significance.