The H2-Metabolizing Prokaryotes

Probing the Origin of the Metabolic Precursor of the CO Ligand in the Catalytic Center of [NiFe] Hydrogenase

“…Although all three glycerolderived carbons occur as CO ligands, the terminal carbon atoms appear to be preferentially incorporated into the cofactor. This observation is supported by a control experiment using [2][3][4][5][6][7][8][9][10][11][12][13] C]glycerol as the substrate (supplemental Fig. S1).…”

“…In contrast to iron-only hydrogenases, which are assembled under completely anaerobic conditions (3,5,6), a number of [NiFe] hydrogenases is synthesized and catalytically active under aerobic conditions (7)(8)(9). Hence, biosynthesis of the metal cofactors needs to be protected against detrimental effects of oxygen.…”

H2 Conversion in the Presence of O2 as Performed by the Membrane‐Bound [NiFe]‐Hydrogenase of Ralstonia eutropha

“…The 34.6 kDa small subunit HoxK coordinates three iron-sulfur clusters in a linear arrangement. [12,[15][16][17] Two [4Fe-4S] clusters reside in the proximal and distal positions, while the [3Fe-4Fe] cluster has a medial location ( Figure 2). Thus, the small subunit provides an electron relay to the primary electron acceptor.…”

“…This b-proteobacterium is capable of growing on explosive gas mixtures, such as 70 % H 2 , 10 % CO 2 , and 20 % O 2 . [12,13] Under these conditions, H 2 serves as the sole energy source while CO 2 is fixed via the CalvinBenson-Bassham cycle to provide the cell with hydrocarbons. [14] In the process of energy conversion, dioxygen acts as terminal electron acceptor leading to the highly exergonic (DH o = À286 kJ mol À1 [6] ) overall reaction shown in Equation (2):…”

A Universal Scaffold for Synthesis of the Fe(CN)2(CO) Moiety of [NiFe] Hydrogenase

“…In this study, we have used this technique to identify of the diatomic ligands in HypCD complexes. The HypCD protein complexes were purified from different genetic backgrounds of two bacterial species, R. eutropha and E. coli, for which extensive information on [NiFe] hydrogenase maturation is available (2,3,10,19). The results reveal that the HypCD complex serves as a scaffold for the assembly of the Fe(CN) 2 (CO) entity of the active site in [NiFe] hydrogenases and provide insights into the chronological order of ligand binding to the HypCD complex.…”