title: Structural basis of a Ni acquisition cycle for [NiFe] hydrogenase by Ni-metallochaperone HypA and its enhancer.
abstract: The Ni atom at the catalytic center of [NiFe] hydrogenases is incorporated by a Ni-metallochaperone, HypA, and a GTPase/ATPase, HypB. We report the crystal structures of the transient complex formed between HypA and ATPase-type HypB (HypBAT) with Ni ions. Transient association between HypA and HypBAT is controlled by the ATP hydrolysis cycle of HypBAT, which is accelerated by HypA. Only the ATP-bound form of HypBAT can interact with HypA and induces drastic conformational changes of HypA. Consequently, upon complex formation, a conserved His residue of HypA comes close to the N-terminal conserved motif of HypA and forms a Ni-binding site, to which a Ni ion is bound with a nearly square-planar geometry. The Ni binding site in the HypABAT complex has a nanomolar affinity (Kd = 7 nM), which is in contrast to the micromolar affinity (Kd = 4 µM) observed with the isolated HypA. The ATP hydrolysis and Ni binding cause conformational changes of HypBAT, affecting its association with HypA. These findings indicate that HypA and HypBAT constitute an ATP-dependent Ni acquisition cycle for [NiFe]-hydrogenase maturation, wherein HypBAT functions as a metallochaperone enhancer and considerably increases the Ni-binding affinity of HypA.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan;
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan;
authors.forename: Takumi
authors.initials: T
authors.lastname: Kawashima
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan;
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Nishitani
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan; Japan Science and Technology Agency, CREST, 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan;
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Kanai
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan;
authors.forename: Takehiko
authors.initials: T
authors.lastname: Wada
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan;
authors.forename: Kenji
authors.initials: K
authors.lastname: Inaba
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan; Japan Science and Technology Agency, CREST, 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan;
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Atomi
authors.affiliation: Japan Science and Technology Agency, CREST, 7, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan; Department of Biotechnology, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan.
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Imanaka
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; miki@kuchem.kyoto-u.ac.jp.
authors.forename: Kunio
authors.initials: K
authors.lastname: Miki
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D018360:Crystallography, X-Ray; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D006868:Hydrolysis; D047908:Intracellular Signaling Peptides and Proteins; D008958:Models, Molecular; D009532:Nickel / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C499625:HypA protein, E coli; D047908:Intracellular Signaling Peptides and Proteins; D009532:Nickel; D000255:Adenosine Triphosphate; C043296:nickel-iron hydrogenase; D006864:Hydrogenase
keywords: X-ray crystallography; metallochaperone; metalloprotein; transient complex