Structural basis of a Ni acquisition cycle for [NiFe] hydrogenase by Ni-metallochaperone HypA and its enhancer

Satoshi Watanabe, Takumi Kawashima, Yuichi Nishitani, Tamotsu Kanai, Takehiko Wada, Kenji Inaba, Haruyuki Atomi, Tadayuki Imanaka, Kunio Miki

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)7701-7706
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number25
Publication statusPublished - 2015 Jun 23


  • Metallochaperone
  • Metalloprotein
  • Transient complex
  • X-ray crystallography

ASJC Scopus subject areas

  • General


Dive into the research topics of 'Structural basis of a Ni acquisition cycle for [NiFe] hydrogenase by Ni-metallochaperone HypA and its enhancer'. Together they form a unique fingerprint.

Cite this