The structure of the Ni-Fe site in the isolated HoxC subunit of the hydrogen-sensing hydrogenase from Ralstonia eutropha.
The regulatory Ni-Fe hydrogenase (RH) from Ralstonia eutropha which forms a [HoxBC]2 complex functions as a hydrogen sensor under aerobic conditions. We have studied a novel Strep-tag isolate of the RH large subunit, HoxC(ST), which lacks the Fe-S clusters of HoxB, allowing for structure determination of the catalytic site by X-ray absorption spectroscopy both at the Ni and, for the first time, also at the Fe K-edge. This technique, together with Fourier-transform infrared spectroscopy, revealed a Ni-Fe site with [O1(CysS)2Ni(II)(mu-SCys)2Fe(II)(CN)2(CO)] structure in about 50% of HoxC(ST) and a [(CysS)2Fe(II)(CN)2(CO)] site lacking Ni in the remainder protein. Possibly both sites may be intermediates in the maturation process of the RH.
Löscher
Simone
S
Freie Universität Berlin, FB Physik, Arnimallee 14, D-14195 Berlin, Germany.
Zebger
Ingo
I
Andersen
Lars K
LK
Hildebrandt
Peter
P
Meyer-Klaucke
Wolfram
W
Haumann
Michael
M
D001426:Bacterial Proteins / Q000737:chemistry*; D020134:Catalytic Domain; D020118:Cupriavidus necator / Q000201:enzymology*; D006859:Hydrogen / Q000378:metabolism; D006864:Hydrogenase / Q000737:chemistry*; D021122:Protein Subunits / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D014965:X-Rays
D001426:Bacterial Proteins; D021122:Protein Subunits; D006859:Hydrogen; C043296:nickel-iron hydrogenase; D006864:Hydrogenase