Taming of a Poison: Biosynthesis of the NiFe-Hydrogenase Cyanide Ligands

  title={Taming of a Poison: Biosynthesis of the NiFe-Hydrogenase Cyanide Ligands},
  author={Stefanie Reissmann and Elisabeth O. Hochleitner and Haofan Wang and Athanasios Paschos and Friedrich Lottspeich and Richard S. Glass and August B{\"o}ck},
  pages={1067 - 1070}
NiFe-hydrogenases have an Ni-Fe site in which the iron has one CO and two CN groups as ligands. Synthesis of the CN ligands requires the activity of two hydrogenase maturation proteins: HypF and HypE. HypF is a carbamoyltransferase that transfers the carbamoyl moiety of carbamoyladenylate to the COOH-terminal cysteine of HypE and thus forms an enzyme-thiocarbamate. HypE dehydrates theS-carbamoyl moiety in an adenosine triphosphate–dependent process to yield the enzyme thiocyanate. Chemical… 
[NiFe]‐Hydrogenase Cofactor Assembly
All of the components of the active site cofactor are derived from inorganic sources abundant on primitive earth, perhaps suggesting that strong selective pressure has maintained this highly effective ancient bioinorganic catalyst of dihydrogen activation throughout evolution.
Crystal structures of the carbamoylated and cyanated forms of HypE for [NiFe] hydrogenase maturation
These structures reveal the detailed interactions around the carbamoylated and cyanated cysteine, providing structural basis for the biological conversion of primary amide to nitrile, and suggest that Lys134 functions as a proton acceptor in the dehydration of thiocarboxamide.
The Influence of Oxygen on [NiFe]–Hydrogenase Cofactor Biosynthesis and How Ligation of Carbon Monoxide Precedes Cyanation
An FT–IR spectroscopic analysis of HypC–HypD isolated from a hydrogenase–competent wild–type strain of Escherichia coli suggests that CO ligation precedes cyanation in vivo, and provides a rationale for the deleterious effects of O2 on in vivo cofactor biosynthesis.
Identification of an Isothiocyanate on the HypEF Complex Suggests a Route for Efficient Cyanyl–Group Channeling during [NiFe]–Hydrogenase Cofactor Generation
The IR signature of HypE could ultimately be assigned to isothiocyanate (–N=C=S) rather than thiOCyanate(–S–C≡N), which has important implications for cyanyl–group channeling during [NiFe]–hydrogenase cofactor generation.
Formyltetrahydrofolate decarbonylase synthesizes the active site CO ligand of O2-tolerant [NiFe] hydrogenase.
In vitro evidence is presented that purified HypX first transfers the formyl group of N10-formyltetrahydrofolate to produce formyl-coenzyme A (formyl-CoA) as central reaction intermediate, which makes it a unique catalyst among the group of CO-releasing enzymes.
Probing the Origin of the Metabolic Precursor of the CO Ligand in the Catalytic Center of [NiFe] Hydrogenase*
The results indicate at least two different pathways for biosynthesis of the CO ligand of [NiFe] hydrogenase, and the data indicate multiple, growth mode-dependent biosynthetic pathways for the carbonyl ligand.
[NiFe]-Hydrogenase Maturation.
Recent work illuminating how the accessory proteins contribute to the maturation of [NiFe]-hydrogenase is reviewed and some of the outstanding questions that remain to be resolved are discussed.
The importance of iron in the biosynthesis and assembly of [NiFe]-hydrogenases
Genetic analyses have provided evidence for the existence of key checkpoints during cofactor biosynthesis and enzyme assembly that ensure correct spatiotemporal maturation of these modular oxidoreductases.


HypF, a Carbamoyl Phosphate-converting Enzyme Involved in [NiFe] Hydrogenase Maturation*
Extensive mutagenesis of the putative functional motifs deduced from the derived amino acid sequence showed a full correlation of the resulting variants between their activity in hydrogenase maturation and the in vitro reactivity with carbamoyl phosphate.
Metal insertion into NiFe-hydrogenases.
The synthesis and the insertion of the metallocentre of NiFe-hydrogenases is a complex process, in which seven maturation enzymes plus ATP, GTP and carbamoyl phosphate are involved and a pathway along which maturation may take place is proposed.
Classification and phylogeny of hydrogenases.
Compelling evidence from sequences and structures indicates that the [NiFe]- and [Fe]-H2ases are phylogenetically distinct classes of proteins, which would be consistent with the phylogenetic distinctiveness of the two classes of H2ases.
Urea cycle: chemical simulation of arginine biosynthesis
The final step in the cycle, namely, the hydrolysis of arginine to urea and ornithine, has been accomplished and Amino group transfer from aspartate has also been demonstrated in the conversion of hypoxanthine to adenine.
Responses of the Fe(CN)2(CO) Unit to Electronic Changes as Related to Its Role in [NiFe]Hydrogenase
The observation of nearly identical infrared spectra in the diatomic (2000 cm-1) region of oxidized forms of [NiFe]hydrogenases, as isolated from Chromatium vinosum (Happe et al. Nature 1997, 385,
The protein–protein interaction map of Helicobacter pylori
A large-scale protein–protein interaction map of the human gastric pathogen Helicobacter pylori is built and the assignment of unannotated proteins to biological pathways is permitted.