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Weaver BR, Perkins LJ, Fernandez Candelaria FO, Burstyn JN, Buller AR. Molecular Determinants of Efficient Cobalt-Substituted Hemoprotein Production in E. coli. ACS Synth Biol 2023; 12:3669-3679. [PMID: 37963151 DOI: 10.1021/acssynbio.3c00481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Exchanging the native iron of heme for other metals yields artificial metalloproteins with new properties for spectroscopic studies and biocatalysis. Recently, we reported a method for the biosynthesis and incorporation of a non-natural metallocofactor, cobalt protoporphyrin IX (CoPPIX), into hemoproteins using the common laboratory strain Escherichia coli BL21(DE3). This discovery inspired us to explore the determinants of metal specificity for metallocofactor biosynthesis in E. coli. Herein, we report detailed kinetic analysis of the ferrochelatase responsible for metal insertion, EcHemH (E. coli ferrochelatase). This enzyme exhibits a small, less than 2-fold preference for Fe2+ over the non-native Co2+ substrate in vitro. To test how mutations impact EcHemH, we used a surrogate metal specificity screen to identify variants with altered metal insertion preferences. This engineering process led to a variant with an ∼30-fold shift in specificity toward Co2+. When assayed in vivo, however, the impact of this mutation is small compared to the effects of alteration of the external metal concentrations. These data suggest that incorporation of cobalt into PPIX is enabled by the native promiscuity of EcHemH coupled with BL21's impaired ability to maintain transition-metal homeostasis. With this knowledge, we generated a method for CoPPIX production in rich media, which yields cobalt-substituted hemoproteins with >95% cofactor purity and yields comparable to standard expression protocols for the analogous native hemoproteins.
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Affiliation(s)
- Brian R Weaver
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Lydia J Perkins
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | | | - Judith N Burstyn
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Andrew R Buller
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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2
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Dali A, Gabler T, Sebastiani F, Destinger A, Furtmüller PG, Pfanzagl V, Becucci M, Smulevich G, Hofbauer S. Active site architecture of coproporphyrin ferrochelatase with its physiological substrate coproporphyrin III: Propionate interactions and porphyrin core deformation. Protein Sci 2023; 32:e4534. [PMID: 36479958 PMCID: PMC9794026 DOI: 10.1002/pro.4534] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/29/2022] [Accepted: 12/03/2022] [Indexed: 12/13/2022]
Abstract
Coproporphyrin ferrochelatases (CpfCs) are enzymes catalyzing the penultimate step in the coproporphyrin-dependent (CPD) heme biosynthesis pathway, which is mainly utilized by monoderm bacteria. Ferrochelatases insert ferrous iron into a porphyrin macrocycle and have been studied for many decades, nevertheless many mechanistic questions remain unanswered to date. Especially CpfCs, which are found in the CPD pathway, are currently in the spotlight of research. This pathway was identified in 2015 and revealed that the correct substrate for these ferrochelatases is coproporphyrin III (cpIII) instead of protoporphyrin IX, as believed prior the discovery of the CPD pathway. The chemistry of cpIII, which has four propionates, differs significantly from protoporphyrin IX, which features two propionate and two vinyl groups. These findings let us to thoroughly describe the physiological cpIII-ferrochelatase complex in solution and in the crystal phase. Here, we present the first crystallographic structure of the CpfC from the representative monoderm pathogen Listeria monocytogenes bound to its physiological substrate, cpIII, together with the in-solution data obtained by resonance Raman and UV-vis spectroscopy, for wild-type ferrochelatase and variants, analyzing propionate interactions. The results allow us to evaluate the porphyrin distortion and provide an in-depth characterization of the catalytically-relevant binding mode of cpIII prior to iron insertion. Our findings are discussed in the light of the observed structural restraints and necessities for this porphyrin-enzyme complex to catalyze the iron insertion process. Knowledge about this initial situation is essential for understanding the preconditions for iron insertion in CpfCs and builds the basis for future studies.
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Affiliation(s)
- Andrea Dali
- Dipartimento di Chimica “Ugo Schiff” – DICUSUniversità di FirenzeSesto Fiorentino (FI)Italy
| | - Thomas Gabler
- Department of ChemistryInstitute of Biochemistry, University of Natural Resources and Life SciencesViennaAustria
| | - Federico Sebastiani
- Dipartimento di Chimica “Ugo Schiff” – DICUSUniversità di FirenzeSesto Fiorentino (FI)Italy
| | - Alina Destinger
- Department of ChemistryInstitute of Biochemistry, University of Natural Resources and Life SciencesViennaAustria
| | - Paul Georg Furtmüller
- Department of ChemistryInstitute of Biochemistry, University of Natural Resources and Life SciencesViennaAustria
| | - Vera Pfanzagl
- Department of ChemistryInstitute of Biochemistry, University of Natural Resources and Life SciencesViennaAustria
| | - Maurizio Becucci
- Dipartimento di Chimica “Ugo Schiff” – DICUSUniversità di FirenzeSesto Fiorentino (FI)Italy
| | - Giulietta Smulevich
- Dipartimento di Chimica “Ugo Schiff” – DICUSUniversità di FirenzeSesto Fiorentino (FI)Italy,INSTM Research Unit of FirenzeSesto Fiorentino (Fi)Italy
| | - Stefan Hofbauer
- Department of ChemistryInstitute of Biochemistry, University of Natural Resources and Life SciencesViennaAustria
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3
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Morris JA, Lickey BS, Liptak MD. Insertion of cobalt into tetrapyrroles. VITAMINS AND HORMONES 2022; 119:1-22. [PMID: 35337616 DOI: 10.1016/bs.vh.2022.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Vitamin B12 is one of the most complex cofactors known, and this chapter will discuss current understanding with regards to the cobalt insertion step of its syntheses. Two total syntheses of vitamin B12 were reported in the 1970s, which remain two of the most exceptional achievements of natural product synthesis. In subsequent years, two distinct biosynthetic pathways were identified in aerobic and anaerobic organisms. For these biosynthetic pathways, selectivity for Co(II) over other divalent metal ions with similar ionic radii and coordination chemistry remains an open question with three competing hypotheses proposed: metal affinity, tetrapyrrole distortion, and product inhibition. A 20 step biosynthetic route to convert 5-aminolevulinic acid (ALA) to vitamin B12 was elucidated in aerobic organisms in the 1990s, where cobalt is inserted relatively late in the pathway by the CobNST multi-protein complex. This chapter includes a mechanistic proposal for this reaction, but the majority of the proposal is based upon analogy to the ChlDHI magnesium chelatase complex as critical data for the cobalt chelatase is lacking. Later, in the 2010s, a distinct 21 step pathway from ALA to vitamin B12 was reported in anaerobic organisms, where cobalt is inserted early in the pathway by the enzyme CbiK. A recent study strongly suggests that the cobalt affinity of CbiK is the origin of cobalt selectivity for CbiK, but several important mechanistic questions remain unanswered. In general, it is expected that significant insight into the cobalt insertion mechanisms of CobNST and CbiK could be derived from additional structural, spectroscopic, and computational data.
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Affiliation(s)
- J A Morris
- Department of Chemistry, University of Vermont, Burlington, VT, United States
| | - B S Lickey
- Department of Chemistry, University of Vermont, Burlington, VT, United States
| | - M D Liptak
- Department of Chemistry, University of Vermont, Burlington, VT, United States.
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Fujishiro T, Ogawa S. The nickel-sirohydrochlorin formation mechanism of the ancestral class II chelatase CfbA in coenzyme F430 biosynthesis. Chem Sci 2021; 12:2172-2180. [PMID: 34163982 PMCID: PMC8179277 DOI: 10.1039/d0sc05439a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The class II chelatase CfbA catalyzes Ni2+ insertion into sirohydrochlorin (SHC) to yield the product nickel-sirohydrochlorin (Ni-SHC) during coenzyme F430 biosynthesis. CfbA is an important ancestor of all the class II chelatase family of enzymes, including SirB and CbiK/CbiX, functioning not only as a nickel-chelatase, but also as a cobalt-chelatase in vitro. Thus, CfbA is a key enzyme in terms of diversity and evolution of the chelatases catalyzing formation of metal-SHC-type of cofactors. However, the reaction mechanism of CfbA with Ni2+ and Co2+ remains elusive. To understand the structural basis of the underlying mechanisms and evolutionary aspects of the class II chelatases, X-ray crystal structures of Methanocaldococcus jannaschii wild-type CfbA with various ligands, including SHC, Ni2+, Ni-SHC, and Co2+ were determined. Further, X-ray crystallographic snapshot analysis captured a unique Ni2+-SHC-His intermediate complex and Co-SHC-bound CfbA, which resulted from a more rapid chelatase reaction for Co2+ than Ni2+. Meanwhile, an in vitro activity assay confirmed the different reaction rates for Ni2+ and Co2+ by CfbA. Based on these structural and functional analyses, the following substrate-SHC-assisted Ni2+ insertion catalytic mechanism was proposed: Ni2+ insertion to SHC is promoted by the support of an acetate side chain of SHC.
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Affiliation(s)
- Takashi Fujishiro
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University Shimo-Okubo 255 Sakura Saitama 338-8570 Japan +81-48-858-9293
| | - Shoko Ogawa
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University Shimo-Okubo 255 Sakura Saitama 338-8570 Japan +81-48-858-9293
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5
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Fujishiro T, Shimada Y, Nakamura R, Ooi M. Structure of sirohydrochlorin ferrochelatase SirB: the last of the structures of the class II chelatase family. Dalton Trans 2019; 48:6083-6090. [PMID: 30778451 DOI: 10.1039/c8dt04727h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crystal structure of Bacillus subtilis SirB, which catalyses the insertion of Fe2+ into the substrate sirohydrochlorin (SHC) in siroheme biosynthesis, is reported herein as the last of the structures of class II chelatases. The structure of SirB with Co2+ showed that the active site of SirB is located at the N-terminal domain with metal-binding amino acid residues His10, Glu43, and His76, which was also predicted for CbiX, but is distinct from the C-terminal active sites of CbiK and HemH. The biosynthetic model reactions using SirB, Co2+ and uroporphyrin I or protoporphyrin IX as a SHC analogue revealed that SirB showed chelatase activity for uroporphyrin I, but not for protoporphyrin IX. Simulations of tetrapyrroles docking to SirB provided an insight into its tetrapyrrole substrate recognition: SHC and uroporphyrin I were suitably bound beside the Co2+ ion-binding site at the active site cavity; protoporphyrin IX was also docked to the active site but its orientation was different from those of the other two tetrapyrroles. Summarizing the present data, it was proposed that the key structural features for substrate recognition of SirB could be the hydrophobic area at the active site as well as the substituents of the tetrapyrroles.
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Affiliation(s)
- Takashi Fujishiro
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
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6
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Liu Q, Tang M, Zeng W, Zhang X, Wang J, Zhou Z. Optimal Size Matching and Minimal Distortion Energy: Implications for Natural Selection by the Macrocycle of the Iron Species in Heme. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201600883] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Qiuhua Liu
- College of Chemistry and Chemical EngineeringCentral South University410083ChangshaChina
- Key Laboratory of Theoretical Organic Chemistry and Functional Molecules of the Ministry of EducationSchool of Chemistry and Chemical EngineeringHunan University of Science and Technology411201XiangtanChina
| | - Min Tang
- Key Laboratory of Theoretical Organic Chemistry and Functional Molecules of the Ministry of EducationSchool of Chemistry and Chemical EngineeringHunan University of Science and Technology411201XiangtanChina
| | - Wennan Zeng
- Key Laboratory of Theoretical Organic Chemistry and Functional Molecules of the Ministry of EducationSchool of Chemistry and Chemical EngineeringHunan University of Science and Technology411201XiangtanChina
| | - Xi Zhang
- Key Laboratory of Theoretical Organic Chemistry and Functional Molecules of the Ministry of EducationSchool of Chemistry and Chemical EngineeringHunan University of Science and Technology411201XiangtanChina
| | - Jianxiu Wang
- College of Chemistry and Chemical EngineeringCentral South University410083ChangshaChina
| | - Zaichun Zhou
- Key Laboratory of Theoretical Organic Chemistry and Functional Molecules of the Ministry of EducationSchool of Chemistry and Chemical EngineeringHunan University of Science and Technology411201XiangtanChina
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7
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Senge MO, MacGowan SA, O'Brien JM. Conformational control of cofactors in nature - the influence of protein-induced macrocycle distortion on the biological function of tetrapyrroles. Chem Commun (Camb) 2016; 51:17031-63. [PMID: 26482230 DOI: 10.1039/c5cc06254c] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Tetrapyrrole-containing proteins are one of the most fundamental classes of enzymes in nature and it remains an open question to give a chemical rationale for the multitude of biological reactions that can be catalyzed by these pigment-protein complexes. There are many fundamental processes where the same (i.e., chemically identical) porphyrin cofactor is involved in chemically quite distinct reactions. For example, heme is the active cofactor for oxygen transport and storage (hemoglobin, myoglobin) and for the incorporation of molecular oxygen in organic substrates (cytochrome P450). It is involved in the terminal oxidation (cytochrome c oxidase) and the metabolism of H2O2 (catalases and peroxidases) and catalyzes various electron transfer reactions in cytochromes. Likewise, in photosynthesis the same chlorophyll cofactor may function as a reaction center pigment (charge separation) or as an accessory pigment (exciton transfer) in light harvesting complexes (e.g., chlorophyll a). Whilst differences in the apoprotein sequences alone cannot explain the often drastic differences in physicochemical properties encountered for the same cofactor in diverse protein complexes, a critical factor for all biological functions must be the close structural interplay between bound cofactors and the respective apoprotein in addition to factors such as hydrogen bonding or electronic effects. Here, we explore how nature can use the same chemical molecule as a cofactor for chemically distinct reactions using the concept of conformational flexibility of tetrapyrroles. The multifaceted roles of tetrapyrroles are discussed in the context of the current knowledge on distorted porphyrins. Contemporary analytical methods now allow a more quantitative look at cofactors in protein complexes and the development of the field is illustrated by case studies on hemeproteins and photosynthetic complexes. Specific tetrapyrrole conformations are now used to prepare bioengineered designer proteins with specific catalytic or photochemical properties.
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Affiliation(s)
- Mathias O Senge
- School of Chemistry, SFI Tetrapyrrole Laboratory, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin 2, Ireland and Medicinal Chemistry, Institute of Molecular Medicine, Trinity Centre for Health Sciences, Trinity College Dublin, St. James's Hospital, Dublin 8, Ireland.
| | - Stuart A MacGowan
- School of Chemistry, SFI Tetrapyrrole Laboratory, Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse Street, Dublin 2, Ireland
| | - Jessica M O'Brien
- Medicinal Chemistry, Institute of Molecular Medicine, Trinity Centre for Health Sciences, Trinity College Dublin, St. James's Hospital, Dublin 8, Ireland.
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8
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Hunter GA, Vankayala SL, Gillam ME, Kearns FL, Lee Woodcock H, Ferreira GC. The conserved active site histidine-glutamate pair of ferrochelatase coordinately catalyzes porphyrin metalation. J PORPHYR PHTHALOCYA 2016. [DOI: 10.1142/s1088424616500395] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ferrochelatase catalyzes the insertion of ferrous iron into protoporphyrin IX to generate heme. Despite recent research on the reaction mechanism of ferrochelatase, the precise roles and localization of individual active site residues in catalysis, particularly those involved in the insertion of the ferrous iron into the protoporphyrin IX substrate, remain controversial. One outstanding question is from which side of the macrocycle of the bound porphyin substrate is the ferrous iron substrate inserted. Pre-steady state kinetic experiments done under single-turnover conditions conclusively demonstrate that metal ion insertion is pH-dependent, and that the conserved active site His-Glu pair coordinately catalyzes the metal ion insertion reaction. Further, p[Formula: see text] calculations and molecular dynamic simulations indicate that the active site His is deprotonated and the protonation state of the Glu relates to the conformational state of ferrochelatase. Specifically, the conserved Glu in the open conformation of ferrochelatase is deprotonated, while it remains protonated in the closed conformation. These findings support not only the role of the His-Glu pair in catalyzing metal ion insertion, as these residues need to be deprotonated to bind the incoming metal ion, but also the importance of the relationship between the protonation state of the Glu residue and the conformation of ferrochelatase. Finally, the results of this study are consistent with our previous proposal that the unwinding of the [Formula: see text]-helix, the major structural determinant of the closed to open conformational transition in ferrochelatase, is associated with the Glu residue binding the Fe[Formula: see text] substrate from a mitochondrial Fe[Formula: see text] donor.
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Affiliation(s)
- Gregory A. Hunter
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA
| | | | - Mallory E. Gillam
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA
| | - Fiona L. Kearns
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA
| | - H. Lee Woodcock
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA
| | - Gloria C. Ferreira
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA
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9
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Gao D, Canard G, Giorgi M, Vanloot P, Balaban TS. Electronic and Steric Effects of the Peripheral Substitution in Deca- and Undecaaryl Metallocorroles. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201301314] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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10
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Haddad R, Lu Y, Quirke JME, Berget P, Sun L, Fettinger JC, Leung K, Qiu Y, Schore NE, van Swol F, Medforth CJ, Shelnutt JA. Steric bulkiness of pyrrole substituents and the out-of-plane deformations of porphyrins: nickel(II) octaisopropylporphyrin and its meso-nitro derivative. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424611003707] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sterically bulky substituents at the β-carbons of the pyrrole rings of porphyrins are sufficient to cause large out-of-plane porphyrin distortions even in the absence of substituent groups at the meso carbons. It is well established that substituents at the meso-positions only or at both the β-pyrrole and the meso-positions are sufficiently bulky to result in large non-planar distortions of the macrocycle. However, no systematic studies of the effects of bulky β-pyrrole substituents alone have been reported. Herein, molecular simulations and X-ray crystallography of nickel(II) 2,3,7,8,12,13,17,18-octa(isopropyl)porphyrin reveal that large out-of-plane distortions (>1.5 Å) are induced by the steric repulsion of the β-isopropyl groups but fail to lead to a single strongly energetically favored conformer. The molecular simulations indicate that multiple conformers differing in the orientation of the isopropyl groups and the macrocycle conformation coexist in solution and this is confirmed by resonance Raman spectroscopy. Large downshifts in the structure-sensitive lines result from the non-planar distortion, and line broadenings result from structural heterogeneity. The heterogeneity originates from tradeoffs between energy contributions from steric repulsion and macrocycle distortion. Simulations for 5-nitro-2,3,7,8,12,13,17,18-octa(isopropyl)porphyrin suggest two possible orientations of the nitro group with respect to the macrocycle mean plane — one nearly vertical (as in the crystal structure) and another that is nearly parallel. INDO/S semiempirical calculations indicate an orbital of the NO2 group resides between the porphyrin frontier orbitals with significant mixing of the nitro and porphyrin orbitals.KEYWORDS: porphyrin, non-planar, resonance Raman, X-ray crystallography, crystal structure, isopropyl, nitro, conformer, molecular mechanics, molecular simulations, density functional theory, steric crowding, conformational heterogeneity.
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Affiliation(s)
- Raid Haddad
- Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, NM 87185-1349, USA
- Departments of Chemistry & Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, USA
| | - Yi Lu
- Departments of Chemistry & Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, USA
| | - J. Martin E. Quirke
- Department of Chemistry, Florida International University, Miami, FL 33199, USA
| | - Patrick Berget
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Lisong Sun
- Departments of Chemistry & Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, USA
| | | | - Kevin Leung
- Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, NM 87185-1349, USA
| | - Yan Qiu
- Departments of Chemistry & Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, USA
| | - Neil E. Schore
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Frank van Swol
- Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, NM 87185-1349, USA
- Departments of Chemistry & Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, USA
| | - Craig J. Medforth
- Departments of Chemistry & Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, USA
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - John A. Shelnutt
- Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, NM 87185-1349, USA
- Department of Chemistry, University of Georgia, Athens, GA 30607, USA
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Hunter GA, Al-Karadaghi S, Ferreira GC. FERROCHELATASE: THE CONVERGENCE OF THE PORPHYRIN BIOSYNTHESIS AND IRON TRANSPORT PATHWAYS. J PORPHYR PHTHALOCYA 2012; 15:350-356. [PMID: 21852895 DOI: 10.1142/s108842461100332x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ferrochelatase (also known as PPIX ferrochelatase; Enzyme Commission number 4.9.9.1.1) catalyzes the insertion of ferrous iron into PPIX to form heme. This reaction unites the biochemically synchronized pathways of porphyrin synthesis and iron transport in nearly all living organisms. The ferrochelatases are an evolutionarily diverse family of enzymes with no more than six active site residues known to be perfectly conserved. The availability of over thirty different crystal structures, including many with bound metal ions or porphyrins, has added tremendously to our understanding of ferrochelatase structure and function. It is generally believed that ferrous iron is directly channeled to ferrochelatase in vivo, but the identity of the suspected chaperone remains uncertain despite much recent progress in this area. Identification of a conserved metal ion binding site at the base of the active site cleft may be an important clue as to how ferrochelatases acquire iron, and catalyze desolvation during transport to the catalytic site to complete heme synthesis.
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Affiliation(s)
- Gregory A Hunter
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, Florida, 33620
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12
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Franco R, Al-Karadaghi S, Ferreira GC. Resonance Raman Spectroscopic Examination of Ferrochelatase-induced Porphyrin Distortion. J PORPHYR PHTHALOCYA 2012; 15:357-363. [PMID: 21776189 DOI: 10.1142/s1088424611003380] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ferrochelatase, the terminal enzyme of the heme biosynthetic pathway, catalyzes the insertion of ferrous iron into protoporphyrin IX to give heme. Resonance Raman spectroscopy has been instrumental in defining the distortion (mode and extent) of the porphyrin substrate, which is a critical step in the catalytic mechanism of ferrochelatase. Saddling is the predominant porphyrin out-of-plane deformation induced upon binding to ferrochelatase. Our analysis demonstrated that the intensity of the γ(15) line, which is assigned to an out-of-plane porphyrin vibration, in resonance Raman spectra obtained for wild-type- and variant ferrochelatase-bound porphyrin, correlates with the saddling deformation undergone by the porphyrin substrate. Further analysis of the three dimensional X-ray structures of bacterial, human and yeast ferrochelatases and the type and extent of distortion of the protein-bound porphyrin substrate and inhibitors using normal structure decomposition, support the view that ferrochelatase catalysis involves binding of a distorted porphyrin substrate and releasing of a flatter, metalated porphyrin.
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Affiliation(s)
- Ricardo Franco
- REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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Kim EJ, Kim P, Lee CH, Sung J, Yoon H, Kim D, Jang WD. Synthesis of stable monoporphyrinate lanthanide(iii) complexes without ancillary ligands. Chem Commun (Camb) 2012; 48:5611-3. [DOI: 10.1039/c2cc31015e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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