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Valer L, Rossetto D, Parkkila T, Sebastianelli L, Guella G, Hendricks AL, Cowan JA, Sang L, Mansy SS. Histidine Ligated Iron-Sulfur Peptides. Chembiochem 2022; 23:e202200202. [PMID: 35674331 PMCID: PMC9400863 DOI: 10.1002/cbic.202200202] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/08/2022] [Indexed: 11/17/2022]
Abstract
Iron-sulfur clusters are thought to be ancient cofactors that could have played a role in early protometabolic systems. Thus far, redox active, prebiotically plausible iron-sulfur clusters have always contained cysteine ligands to the cluster. However, extant iron-sulfur proteins can be found to exploit other modes of binding, including ligation by histidine residues, as seen with [2Fe-2S] Rieske and MitoNEET proteins. Here, we investigated the ability of cysteine- and histidine-containing peptides to coordinate a mononuclear Fe2+ center and a [2Fe-2S] cluster and compare their properties with purified iron-sulfur proteins. The iron-sulfur peptides were characterized by UV-vis, circular dichroism, and paramagnetic NMR spectroscopies and cyclic voltammetry. Small (≤6 amino acids) peptides can coordinate [2Fe-2S] clusters through a combination of cysteine and histidine residues with similar reduction potentials as their corresponding proteins. Such complexes may have been important for early cell-like systems.
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Affiliation(s)
- Luca Valer
- D-CIBIOUniversity of Trentovia Sommarive 938123Trento 28123Italy
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Daniele Rossetto
- D-CIBIOUniversity of Trentovia Sommarive 938123Trento 28123Italy
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Taylor Parkkila
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Lorenzo Sebastianelli
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Graziano Guella
- Department of PhysicsUniversity of TrentoVia Sommarive 14Trento38123Italy
| | - Amber L. Hendricks
- Department of Chemistry and BiochemistryThe Ohio State University100 West 18th AveColumbusOH 43210USA
| | - James A. Cowan
- Department of Chemistry and BiochemistryThe Ohio State University100 West 18th AveColumbusOH 43210USA
| | - Lingzi Sang
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Sheref S. Mansy
- D-CIBIOUniversity of Trentovia Sommarive 938123Trento 28123Italy
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
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2
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Hecel A, Kola A, Valensin D, Kozlowski H, Rowinska-Zyrek M. Metal specificity of the Ni(II) and Zn(II) binding sites of the N-terminal and G-domain of E. coli HypB. Dalton Trans 2021; 50:12635-12647. [PMID: 34545874 DOI: 10.1039/d1dt02126e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
HypB is one of the chaperones required for proper nickel insertion into [NiFe]-hydrogenase. Escherichia coli HypB has two potential Ni(II) and Zn(II) binding sites-the N-terminal one and the so-called GTPase one. The metal-loaded HypB-SlyD metallochaperone complex activates nickel release from the N-terminal HypB site. In this work, we focus on the metal selectivity of the two HypB metal binding sites and show that (i) the N-terminal region binds Zn(II) and Ni(II) ions with higher affinity than the G-domain and (ii) the lower affinity G domain binds Zn(II) more effectively than Ni(II). In addition, the high affinity N-terminal domain, both in water and membrane mimicking SDS solution, has a larger affinity towards Zn(II) than Ni(II), while an opposite situation is observed at basic pH; at pH 7.4, the affinity of this region towards both metals is almost the same. The N-terminal HypB region is also more effective in Ni(II) binding than the previously studied SlyD metal binding regions. Considering that the nickel chaperone SlyD activates the release of nickel and blocks the release of zinc from the N-terminal high-affinity metal site of HypB, we may speculate that such pH-dependent metal affinity might modulate HypB interactions with SlyD, being dependent on both pH and the protein's metal status.
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Affiliation(s)
- Aleksandra Hecel
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland.
| | - Arian Kola
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via A. Moro 2, 53100 Siena, Italy
| | - Daniela Valensin
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via A. Moro 2, 53100 Siena, Italy
| | - Henryk Kozlowski
- Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland. .,Institute of Health Sciences, University of Opole, 68 Katowicka St., 45-060 Opole, Poland
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3
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Lukatskaya MR, Feng D, Bak SM, To JWF, Yang XQ, Cui Y, Feldblyum JI, Bao Z. Understanding the Mechanism of High Capacitance in Nickel Hexaaminobenzene-Based Conductive Metal-Organic Frameworks in Aqueous Electrolytes. ACS NANO 2020; 14:15919-15925. [PMID: 33166110 DOI: 10.1021/acsnano.0c07292] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recently, intrinsically conductive metal-organic frameworks (MOFs) have demonstrated promising performance in fast-charging energy storage applications and may outperform some current electrode materials (e.g., porous carbons) for supercapacitors in terms of both gravimetric and volumetric capacitance. In this report, we examine the mechanism of high capacitance in a nickel hexaaminobenzene-based MOF (NiHAB). Using a combination of in situ Raman and X-ray absorption spectroscopies, as well as detailed electrochemical studies in a series of aqueous electrolytes, we demonstrate that the charge storage mechanism is, in fact, a pH-dependent surface pseudocapacitance, and unlike typical inorganic systems, where transition metals change oxidation state during charge/discharge cycles, NiHAB redox activity is ligand-centered.
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Affiliation(s)
- Maria R Lukatskaya
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Dawei Feng
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Seong-Min Bak
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - John W F To
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Xiao-Qing Yang
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Yi Cui
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Jeremy I Feldblyum
- Department of Chemistry, University at Albany, SUNY, Albany, New York 12222, United States
| | - Zhenan Bao
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
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4
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Wang X, Yang S, Yu Y, Dou M, Zhang Z, Wang F. Low-loading Pt nanoparticles embedded on Ni, N-doped carbon as superior electrocatalysts for oxygen reduction. Catal Sci Technol 2020. [DOI: 10.1039/c9cy01654f] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A synergetic catalytic system was built based on Pt NPs and atomic Ni–N–C joint active sites for better ORR electrocatalysis.
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Affiliation(s)
- Xinliang Wang
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Electrochemical Process and Technology for Materials
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Shaoxuan Yang
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Electrochemical Process and Technology for Materials
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Yihuan Yu
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Electrochemical Process and Technology for Materials
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Meiling Dou
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Electrochemical Process and Technology for Materials
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Zhengping Zhang
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Electrochemical Process and Technology for Materials
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Feng Wang
- State Key Laboratory of Chemical Resource Engineering
- Beijing Key Laboratory of Electrochemical Process and Technology for Materials
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
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5
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Urbina J, Patil A, Fujishima K, Paulino-Lima IG, Saltikov C, Rothschild LJ. A new approach to biomining: Bioengineering surfaces for metal recovery from aqueous solutions. Sci Rep 2019; 9:16422. [PMID: 31712654 PMCID: PMC6848105 DOI: 10.1038/s41598-019-52778-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 09/26/2019] [Indexed: 02/06/2023] Open
Abstract
Electronics waste production has been fueled by economic growth and the demand for faster, more efficient consumer electronics. The glass and metals in end-of-life electronics components can be reused or recycled; however, conventional extraction methods rely on energy-intensive processes that are inefficient when applied to recycling e-waste that contains mixed materials and small amounts of metals. To make e-waste recycling economically viable and competitive with obtaining raw materials, recovery methods that lower the cost of metal reclamation and minimize environmental impact need to be developed. Microbial surface adsorption can aid in metal recovery with lower costs and energy requirements than traditional metal-extraction approaches. We introduce a novel method for metal recovery by utilizing metal-binding peptides to functionalize fungal mycelia and enhance metal recovery from aqueous solutions such as those found in bioremediation or biomining processes. Using copper-binding as a proof-of-concept, we compared binding parameters between natural motifs and those derived in silico, and found comparable binding affinity and specificity for Cu. We then combined metal-binding peptides with chitin-binding domains to functionalize a mycelium-based filter to enhance metal recovery from a Cu-rich solution. This finding suggests that engineered peptides could be used to functionalize biological surfaces to recover metals of economic interest and allow for metal recovery from metal-rich effluent with a low environmental footprint, at ambient temperatures, and under circumneutral pH.
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Affiliation(s)
- Jesica Urbina
- University of California Santa Cruz, Department of Microbiology and Environmental Toxicology, Santa Cruz, CA, 95064, USA.
| | - Advait Patil
- Universities Space Research Association, Mountain View, CA, 94043, USA
| | - Kosuke Fujishima
- Tokyo Institute of Technology, Earth-Life Science Institute (ELSI), Tokyo, Japan
| | | | - Chad Saltikov
- University of California Santa Cruz, Department of Microbiology and Environmental Toxicology, Santa Cruz, CA, 95064, USA
| | - Lynn J Rothschild
- NASA Ames Research Center, Space Biosciences Division, Moffett Field, CA, 94035, USA
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6
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Lacasse MJ, Summers KL, Khorasani-Motlagh M, George GN, Zamble DB. Bimodal Nickel-Binding Site on Escherichia coli [NiFe]-Hydrogenase Metallochaperone HypA. Inorg Chem 2019; 58:13604-13618. [PMID: 31273981 DOI: 10.1021/acs.inorgchem.9b00897] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
[NiFe]-hydrogenase enzymes catalyze the reversible oxidation of hydrogen at a bimetallic cluster and 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 effects 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 nonhydrolyzable 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.
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Affiliation(s)
- Michael J Lacasse
- Department of Chemistry , University of Toronto , Toronto , Ontario M5S 3H6 , Canada
| | - Kelly L Summers
- Department of Chemistry , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5C9 , Canada
| | | | - Graham N George
- Department of Geological Sciences , University of Saskatchewan , Saskatoon , Saskatchewan S7N 5E2 , Canada
| | - Deborah B Zamble
- Department of Chemistry , University of Toronto , Toronto , Ontario M5S 3H6 , Canada.,Department of Biochemistry , University of Toronto , Toronto , Ontario M5S 1A8 , Canada
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7
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Complex formation between the Escherichia coli [NiFe]-hydrogenase nickel maturation factors. Biometals 2019; 32:521-532. [DOI: 10.1007/s10534-019-00173-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 01/18/2019] [Indexed: 11/26/2022]
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8
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Khorasani-Motlagh M, Lacasse MJ, Zamble DB. High-affinity metal binding by the Escherichia coli [NiFe]-hydrogenase accessory protein HypB is selectively modulated by SlyD. Metallomics 2018; 9:482-493. [PMID: 28352890 DOI: 10.1039/c7mt00037e] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
[NiFe]-hydrogenase, which catalyzes the reversible conversion between hydrogen gas and protons, is a vital component of the metabolism of many pathogens. Maturation of [NiFe]-hydrogenase requires selective nickel insertion that is completed, in part, by the metallochaperones SlyD and HypB. Escherichia coli HypB binds nickel with sub-picomolar affinity, and the formation of the HypB-SlyD complex activates nickel release from the high-affinity site (HAS) of HypB. In this study, the metal selectivity of this process was investigated. Biochemical experiments revealed that the HAS of full length HypB can bind stoichiometric zinc. Moreover, in contrast to the acceleration of metal release observed with nickel-loaded HypB, SlyD blocks the release of zinc from the HypB HAS. X-ray absorption spectroscopy (XAS) demonstrated that SlyD does not impact the primary coordination sphere of nickel or zinc bound to the HAS of HypB. Instead, computational modeling and XAS of HypB loaded with nickel or zinc indicated that zinc binds to HypB with a different coordination sphere than nickel. The data suggested that Glu9, which is not a nickel ligand, directly coordinates zinc. These results were confirmed through the characterization of E9A-HypB, which afforded weakened zinc affinity compared to wild-type HypB but similar nickel affinity. This mutant HypB fully supports the production of [NiFe]-hydrogenase in E. coli. Altogether, these results are consistent with the model that the HAS of HypB functions as a nickel site during [NiFe]-hydrogenase enzyme maturation and that the metal selectivity is controlled by activation of metal release by SlyD.
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9
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Schnicker NJ, De Silva SM, Todd JD, Dey M. Structural and Biochemical Insights into Dimethylsulfoniopropionate Cleavage by Cofactor-Bound DddK from the Prolific Marine Bacterium Pelagibacter. Biochemistry 2017; 56:2873-2885. [DOI: 10.1021/acs.biochem.7b00099] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Nicholas J. Schnicker
- Department
of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Saumya M. De Silva
- Department
of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
| | - Jonathan D. Todd
- School
of Biological Sciences, University of East Anglia, Norwich Research
Park, Norwich NR4 7TJ, United Kingdom
| | - Mishtu Dey
- Department
of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States
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10
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Lacasse MJ, Douglas CD, Zamble DB. Mechanism of Selective Nickel Transfer from HypB to HypA, Escherichia coli [NiFe]-Hydrogenase Accessory Proteins. Biochemistry 2016; 55:6821-6831. [PMID: 27951644 DOI: 10.1021/acs.biochem.6b00706] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[NiFe]-hydrogenase enzymes catalyze the reversible reduction of protons to molecular hydrogen and serve as a vital component of the metabolism of many pathogens. The synthesis of the bimetallic catalytic center requires a suite of accessory proteins, and the penultimate step, nickel insertion, is facilitated by the metallochaperones HypA and HypB. In Escherichia coli, nickel moves from a site in the GTPase domain of HypB to HypA in a process accelerated by GDP. To determine how the transfer of nickel is controlled, the impacts of HypA and nucleotides on the properties of HypB were examined. Integral to this work was His2Gln HypA, a mutant with attenuated nickel affinity that does not support hydrogenase production in E. coli. This mutation inhibits the translocation of nickel from HypB. H2Q-HypA does not modulate the apparent metal affinity of HypB, but the stoichiometry and stability of the HypB-nickel complex are modulated by the nucleotide. Furthermore, the HypA-HypB interaction was detected by gel filtration chromatography if HypB was loaded with GDP, but not a GTP analogue, and the protein complex dissociated upon binding of nickel to His2 of HypA. In contrast, a nucleotide does not modulate the binding of zinc to HypB, and loading zinc into the GTPase domain of HypB inhibits formation of the complex with HypA. These results demonstrate that GTP hydrolysis controls both metal binding and protein-protein interactions, conferring selective and directional nickel transfer during [NiFe]-hydrogenase biosynthesis.
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Affiliation(s)
- Michael J Lacasse
- Department of Chemistry, University of Toronto , Toronto, Ontario, Canada M5S 3H6
| | - Colin D Douglas
- Department of Chemistry, University of Toronto , Toronto, Ontario, Canada M5S 3H6
| | - Deborah B Zamble
- Department of Chemistry, University of Toronto , Toronto, Ontario, Canada M5S 3H6.,Department of Biochemistry, University of Toronto , Toronto, Ontario, Canada M5S 1A8
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11
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Abstract
[NiFe]-hydrogenases catalyze the reversible conversion of hydrogen gas into protons and electrons and are vital metabolic components of many species of bacteria and archaea. At the core of this enzyme is a sophisticated catalytic center comprising nickel and iron, as well as cyanide and carbon monoxide ligands, which is anchored to the large hydrogenase subunit through cysteine residues. The production of this multicomponent active site is accomplished by a collection of accessory proteins and can be divided into discrete stages. The iron component is fashioned by the proteins HypC, HypD, HypE, and HypF, which functionalize iron with cyanide and carbon monoxide. Insertion of the iron center signals to the metallochaperones HypA, HypB, and SlyD to selectively deliver the nickel to the active site. A specific protease recognizes the completed metal cluster and then cleaves the C-terminus of the large subunit, resulting in a conformational change that locks the active site in place. Finally, the large subunit associates with the small subunit, and the complete holoenzyme translocates to its final cellular position. Beyond this broad overview of the [NiFe]-hydrogenase maturation process, biochemical and structural studies are revealing the fundamental underlying molecular mechanisms. Here, we review recent work illuminating how the accessory proteins contribute to the maturation of [NiFe]-hydrogenase and discuss some of the outstanding questions that remain to be resolved.
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Affiliation(s)
- Michael J Lacasse
- Department of Chemistry, University of Toronto , Toronto, Ontario, Canada M5S 3H6
| | - Deborah B Zamble
- Department of Chemistry, University of Toronto , Toronto, Ontario, Canada M5S 3H6.,Department of Biochemistry, University of Toronto , Toronto, Ontario, Canada M5S 1A8
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12
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Chivers PT. Cobalt and Nickel. BINDING, TRANSPORT AND STORAGE OF METAL IONS IN BIOLOGICAL CELLS 2014. [DOI: 10.1039/9781849739979-00381] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Cobalt and nickel play key roles in biological systems as cofactors in a small number of important enzymes. The majority of these are found in microbes. Evidence for direct roles for Ni(II) and Co(II) enzymes in higher organisms is limited, with the exception of the well-known requirement for the cobalt-containing vitamin B12 cofactor and the Ni-dependent urease in plants. Nonetheless, nickel in particular plays a key role in human health because of its essential role in microbes that inhabit various growth niches within the body. These roles can be beneficial, as can be seen with the anaerobic production and consumption of H2 in the digestive tract by bacteria and archaea that results in increased yields of short-chain fatty acids. In other cases, nickel has an established role in the establishment of pathogenic infection (Helicobacter pylori urease and colonization of the stomach). The synthesis of Co- and Ni-containing enzymes requires metal import from the extracellular milieu followed by the targeting of these metals to the appropriate protein and enzymes involved in metallocluster or cofactor biosynthesis. These metals are toxic in excess so their levels must be regulated carefully. This complex pathway of metalloenzyme synthesis and intracellular homeostasis requires proteins that can specifically recognize these metals in a hierarchical manner. This chapter focuses on quantitative and structural details of the cobalt and nickel binding sites in transport, trafficking and regulatory proteins involved in cobalt and nickel metabolism in microbes.
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Affiliation(s)
- Peter T. Chivers
- Department of Chemistry, School of Biological and Biomedical Sciences, and Biophysical Sciences Institute, Durham University Durham UK
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13
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Douglas CD, Ngu TT, Kaluarachchi H, Zamble DB. Metal transfer within the Escherichia coli HypB-HypA complex of hydrogenase accessory proteins. Biochemistry 2013; 52:6030-9. [PMID: 23899293 DOI: 10.1021/bi400812r] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The maturation of [NiFe]-hydrogenase in Escherichia coli is a complex process involving many steps and multiple accessory proteins. The two accessory proteins HypA and HypB interact with each other and are thought to cooperate to insert nickel into the active site of the hydrogenase-3 precursor protein. Both of these accessory proteins bind metal individually, but little is known about the metal-binding activities of the proteins once they assemble together into a functional complex. In this study, we investigate how complex formation modulates metal binding to the E. coli proteins HypA and HypB. This work lead to a re-evaluation of the HypA nickel affinity, revealing a KD on the order of 10(-8) M. HypA can efficiently remove nickel, but not zinc, from the metal-binding site in the GTPase domain of HypB, a process that is less efficient when complex formation between HypA and HypB is disrupted. Furthermore, nickel release from HypB to HypA is specifically accelerated when HypB is loaded with GDP, but not GTP. These results are consistent with the HypA-HypB complex serving as a transfer step in the relay of nickel from membrane transporter to its final destination in the hydrogenase active site and suggest that this complex contributes to the metal fidelity of this pathway.
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Affiliation(s)
- Colin D Douglas
- Department of Chemistry, University of Toronto , 80 St. George St., Toronto, Ontario M5S 3H6, Canada
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