Hydrogenases from methanogenic archaea, nickel, a novel cofactor, and H2 storage.
Most methanogenic archaea reduce CO(2) with H(2) to CH(4). For the activation of H(2), they use different [NiFe]-hydrogenases, namely energy-converting [NiFe]-hydrogenases, heterodisulfide reductase-associated [NiFe]-hydrogenase or methanophenazine-reducing [NiFe]-hydrogenase, and F(420)-reducing [NiFe]-hydrogenase. The energy-converting [NiFe]-hydrogenases are phylogenetically related to complex I of the respiratory chain. Under conditions of nickel limitation, some methanogens synthesize a nickel-independent [Fe]-hydrogenase (instead of F(420)-reducing [NiFe]-hydrogenase) and by that reduce their nickel requirement. The [Fe]-hydrogenase harbors a unique iron-guanylylpyridinol cofactor (FeGP cofactor), in which a low-spin iron is ligated by two CO, one C(O)CH(2)-, one S-CH(2)-, and a sp(2)-hybridized pyridinol nitrogen. Ligation of the iron is thus similar to that of the low-spin iron in the binuclear active-site metal center of [NiFe]- and [FeFe]-hydrogenases. Putative genes for the synthesis of the FeGP cofactor have been identified. The formation of methane from 4 H(2) and CO(2) catalyzed by methanogenic archaea is being discussed as an efficient means to store H(2).
Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg, Germany. thauer@mpi-marburg.mpg.de
Rudolf K
RK
Thauer
Anne-Kristin
AK
Kaster
Meike
M
Goenrich
Michael
M
Schick
Takeshi
T
Hiromoto
Seigo
S
Shima
D001105:Archaea / Q000201:enzymology* / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D006864:Hydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009532:Nickel
D009532:Nickel; D006859:Hydrogen; D006864:Hydrogenase