The F₄₂₀-reducing [NiFe]-hydrogenase complex from Methanothermobacter marburgensis, the first X-ray structure of a group 3 family member.The reversible redox reaction between coenzyme F420 and H2 to F420H2 is catalyzed by an F420-reducing [NiFe]-hydrogenase (FrhABG), which is an enzyme of the energy metabolism of methanogenic archaea.  We report on the crystal structure of FrhABG from Methanothermobacter marburgensis at 1.7Å resolution and compare it with the structures of group 1 [NiFe]-hydrogenases, the only group structurally characterized yet. 
THERM