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Bimodal Nickel-Binding Site on Escherichia coli [NiFe]-Hydrogenase Metallochaperone HypA

Journal Article · · Inorganic Chemistry
 [1];  [2];  [3];  [4];  [5]
  1. Univ. of Toronto, ON (Canada). Dept. of Chemistry; University of Toronto
  2. Univ. of Saskatchewan, Saskatoon, SK (Canada). Dept. of Chemistry
  3. Univ. of Toronto, ON (Canada). Dept. of Chemistry
  4. Univ. of Saskatchewan, Saskatoon, SK (Canada). Dept. of Geological Sciences
  5. Univ. of Toronto, ON (Canada). Dept. of Chemistry, and Dept. of Biochemistry
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[NiFe]-hydrogenase enzymes catalyze the reversible oxidation of hydrogen at a bimetallic active site and they are used by bacteria and archaea for anaerobic growth and pathogenesis. Maturation of the [NiFe]-hydrogenase requires several accessory proteins to assemble and insert the components of the active site. The penultimate maturation step is the delivery of nickel to a primed hydrogenase enzyme precursor protein, a process that is accomplished by two nickel metallochaperones, the accessory protein HypA and the GTPase HypB. Recent work demonstrated that nickel is rapidly transferred to HypA from GDP-loaded HypB within the context of a protein complex in a nickel selective and unidirectional process. To investigate the mechanism of metal transfer, we examined the allosteric effect of nucleotide cofactors and partner-proteins on the nickel environments of HypA and HypB by using a combination of biochemical, microbiological, computational, and spectroscopic techniques. We observed that loading HypB with either GDP or a non-hydrolyzable GTP analogue resulted in a similar nickel environment. In addition, interaction with a mutant version of HypA with disrupted nickel binding, H2Q-HypA, does not induce substantial changes to the HypB G-domain nickel site. Instead, the results demonstrate that HypB modifies the acceptor site of HypA. Analysis of a peptide maquette derived from the N-terminus of HypA revealed that nickel is predominately coordinated by atoms from the N-terminal Met-His- motif. Furthermore, HypA is capable of two nickel-binding modes at the N-terminus, a HypB-induced mode and a binding mode that mirrors the peptide maquette. Collectively, these results reveal that HypB brings about changes in the nickel coordination of HypA, providing a mechanism for the HypB-dependent control of the acquisition and release of nickel by HypA.
Research Organization:
Univ. of Toronto, ON (Canada)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
AC02-76SF00515
OSTI ID:
1529485
Journal Information:
Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 20 Vol. 58; ISSN 0020-1669
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English

Figures / Tables (10)

Figure 1(p. 22)figure Figure 1
Table 1(p. 23)table Table 1
Figure 2(p. 27)figure Figure 2
Figure 3(p. 30)figure Figure 3
Figure 4(p. 34)figure Figure 4
Table 2(p. 36)table Table 2
Figure 5(p. 39)figure Figure 5
Table 3(p. 40)table Table 3
Figure 6(p. 42)figure Figure 6
Figure 7(p. 51)figure Figure 7

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Related Subjects

08 HYDROGEN
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
[NiFe]-hydrogenase maturation
metal transfer
metallochaperones
nickel proteins