title: Crystal structures of [NiFe] hydrogenase maturation proteins HypC, HypD, and HypE: insights into cyanation reaction by thiol redox signaling.
abstract: [NiFe] hydrogenase maturation proteins HypC, HypD, and HypE catalyze the insertion and cyanation of the iron center of [NiFe] hydrogenases by an unknown mechanism. We have determined the crystal structures of HypC, HypD, and HypE from Thermococcus kodakaraensis KOD1 at 1.8 A, 2.07 A, and 1.55 A resolution, respectively. The structure of HypD reveals its probable iron binding and active sites for cyanation. An extended conformation of each conserved motif of HypC and HypE allows the essential cysteine residues of both proteins to interact with the active site of HypD. Furthermore, the C-terminal tail of HypE is shown to exist in an ATP-dependent dynamic equilibrium between outward and inward conformations. Unexpectedly, the [4Fe-4S] cluster environment of HypD is quite similar to that of ferredoxin:thioredoxin reductase (FTR), indicating the existence of a redox cascade similar to the FTR system. These results suggest a cyanation reaction mechanism via unique thiol redox signaling in the HypCDE complex.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Rie
authors.initials: R
authors.lastname: Matsumi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Arai
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Atomi
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Imanaka
authors.forename: Kunio
authors.initials: K
authors.lastname: Miki
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D019843:Archaeal Proteins / Q000737:chemistry*; D001665:Binding Sites; D044822:Biodiversity; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D004220:Disulfides / Q000737:chemistry; D006864:Hydrogenase / Q000737:chemistry*; D007501:Iron / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry; D017433:Protein Structure, Secondary; D015398:Signal Transduction / Q000187:drug effects; D055672:Static Electricity; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D019712:Thermococcus / Q000737:chemistry*
chemical_list: D019843:Archaeal Proteins; D004220:Disulfides; D007506:Iron-Sulfur Proteins; D008024:Ligands; D013438:Sulfhydryl Compounds; D000255:Adenosine Triphosphate; D007501:Iron; D010088:Oxidoreductases; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; C021588:ferredoxin-thioredoxin reductase