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Olczak T, Śmiga M, Antonyuk SV, Smalley JW. Hemophore-like proteins of the HmuY family in the oral and gut microbiome: unraveling the mystery of their evolution. Microbiol Mol Biol Rev 2024; 88:e0013123. [PMID: 38305743 PMCID: PMC10966948 DOI: 10.1128/mmbr.00131-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024] Open
Abstract
SUMMARY Heme (iron protoporphyrin IX, FePPIX) is the main source of iron and PPIX for host-associated pathogenic bacteria, including members of the Bacteroidota (formerly Bacteroidetes) phylum. Porphyromonas gingivalis, a keystone oral pathogen, uses a unique heme uptake (Hmu) system, comprising a hemophore-like protein, designated as the first member of the novel HmuY family. Compared to classical, secreted hemophores utilized by Gram-negative bacteria or near-iron transporter domain-based hemophores utilized by Gram-positive bacteria, the HmuY family comprises structurally similar proteins that have undergone diversification during evolution. The best characterized are P. gingivalis HmuY and its homologs from Tannerella forsythia (Tfo), Prevotella intermedia (PinO and PinA), Bacteroides vulgatus (Bvu), and Bacteroides fragilis (BfrA, BfrB, and BfrC). In contrast to the two histidine residues coordinating heme iron in P. gingivalis HmuY, Tfo, PinO, PinA, Bvu, and BfrA preferentially use two methionine residues. Interestingly, BfrB, despite conserved methionine residue, binds the PPIX ring without iron coordination. BfrC binds neither heme nor PPIX in keeping with the lack of conserved histidine or methionine residues used by other members of the HmuY family. HmuY competes for heme binding and heme sequestration from host hemoproteins with other members of the HmuY family to increase P. gingivalis competitiveness. The participation of HmuY in the host immune response confirms its relevance in relation to the survival of P. gingivalis and its ability to induce dysbiosis not only in the oral microbiome but also in the gut microbiome or other host niches, leading to local injuries and involvement in comorbidities.
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Affiliation(s)
- Teresa Olczak
- Laboratory of Medical Biology, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
| | - Michał Śmiga
- Laboratory of Medical Biology, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
| | - Svetlana V. Antonyuk
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, the University of Liverpool, Liverpool, United Kingdom
| | - John W. Smalley
- Institute of Life Course and Medical Sciences, School of Dentistry, the University of Liverpool, Liverpool, United Kingdom
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De Simone G, di Masi A, Tundo GR, Coletta M, Ascenzi P. Nitrite Reductase Activity of Ferrous Nitrobindins: A Comparative Study. Int J Mol Sci 2023; 24:ijms24076553. [PMID: 37047528 PMCID: PMC10094804 DOI: 10.3390/ijms24076553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
Nitrobindins (Nbs) are all-β-barrel heme proteins spanning from bacteria to Homo sapiens. They inactivate reactive nitrogen species by sequestering NO, converting NO to HNO2, and promoting peroxynitrite isomerization to NO3−. Here, the nitrite reductase activity of Nb(II) from Mycobacterium tuberculosis (Mt-Nb(II)), Arabidopsis thaliana (At-Nb(II)), Danio rerio (Dr-Nb(II)), and Homo sapiens (Hs-Nb(II)) is reported. This activity is crucial for the in vivo production of NO, and thus for the regulation of blood pressure, being of the utmost importance for the blood supply to poorly oxygenated tissues, such as the eye retina. At pH 7.3 and 20.0 °C, the values of the second-order rate constants (i.e., kon) for the reduction of NO2− to NO and the concomitant formation of nitrosylated Mt-Nb(II), At-Nb(II), Dr-Nb(II), and Hs-Nb(II) (Nb(II)-NO) were 7.6 M−1 s−1, 9.3 M−1 s−1, 1.4 × 101 M−1 s−1, and 5.8 M−1 s−1, respectively. The values of kon increased linearly with decreasing pH, thus indicating that the NO2−-based conversion of Nb(II) to Nb(II)-NO requires the involvement of one proton. These results represent the first evidence for the NO2 reductase activity of Nbs(II), strongly supporting the view that Nbs are involved in NO metabolism. Interestingly, the nitrite reductase reactivity of all-β-barrel Nbs and of all-α-helical globins (e.g., myoglobin) was very similar despite the very different three-dimensional fold; however, differences between all-α-helical globins and all-β-barrel Nbs suggest that nitrite reductase activity appears to be controlled by distal steric barriers, even though a more complex regulatory mechanism can be also envisaged.
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Affiliation(s)
| | | | - Grazia R. Tundo
- Dipartimento di Scienze Cliniche e Medicina Traslazionale, Università di Roma Tor Vergata, 00133 Roma, Italy
| | | | - Paolo Ascenzi
- Laboratorio Interdipartimentale di Microscopia Elettronica, Università Roma Tre, 00146 Roma, Italy
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3
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Siemińska K, Cierpisz P, Śmiga M, Olczak T. Porphyromonas gingivalis HmuY and Bacteroides vulgatus Bvu-A Novel Competitive Heme Acquisition Strategy. Int J Mol Sci 2021; 22:ijms22052237. [PMID: 33668119 PMCID: PMC7956564 DOI: 10.3390/ijms22052237] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 02/12/2021] [Accepted: 02/20/2021] [Indexed: 12/13/2022] Open
Abstract
Human oral and gut microbiomes are crucial for maintenance of homeostasis in the human body. Porphyromonas gingivalis, the key etiologic agent of chronic periodontitis, can cause dysbiosis in the mouth and gut, which results in local and systemic infectious inflammatory diseases. Our previous work resulted in extensive biochemical and functional characterization of one of the major P. gingivalis heme acquisition systems (Hmu), with the leading role played by the HmuY hemophore-like protein. We continued our studies on the homologous heme acquisition protein (Bvu) expressed by Bacteroides vulgatus, the dominant species of the gut microbiome. Results from spectrophotometric experiments showed that Bvu binds heme preferentially under reducing conditions using Met145 and Met172 as heme iron-coordinating ligands. Bvu captures heme bound to human serum albumin and only under reducing conditions. Importantly, HmuY is able to sequester heme complexed to Bvu. This is the first study demonstrating that B. vulgatus expresses a heme-binding hemophore-like protein, thus increasing the number of members of a novel HmuY-like family. Data gained in this study confirm the importance of HmuY in the context of P. gingivalis survival in regard to its ability to cause dysbiosis also in the gut microbiome.
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Leboffe L, di Masi A, Polticelli F, Trezza V, Ascenzi P. Structural Basis of Drug Recognition by Human Serum Albumin. Curr Med Chem 2020; 27:4907-4931. [DOI: 10.2174/0929867326666190320105316] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 02/12/2019] [Accepted: 03/06/2019] [Indexed: 12/18/2022]
Abstract
Background:
Human serum albumin (HSA), the most abundant protein in plasma,
is a monomeric multi-domain macromolecule with at least nine binding sites for endogenous
and exogenous ligands. HSA displays an extraordinary ligand binding capacity as a depot and
carrier for many compounds including most acidic drugs. Consequently, HSA has the potential
to influence the pharmacokinetics and pharmacodynamics of drugs.
Objective:
In this review, the structural determinants of drug binding to the multiple sites of
HSA are analyzed and discussed in detail. Moreover, insight into the allosteric and competitive
mechanisms underpinning drug recognition, delivery, and efficacy are analyzed and discussed.
Conclusion:
As several factors can modulate drug binding to HSA (e.g., concurrent administration
of drugs competing for the same binding site, ligand binding to allosteric-coupled
clefts, genetic inherited diseases, and post-translational modifications), ligand binding to HSA
is relevant not only under physiological conditions, but also in the pharmacological therapy
management.
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Affiliation(s)
- Loris Leboffe
- Department of Sciences, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy
| | - Alessandra di Masi
- Department of Sciences, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy
| | - Fabio Polticelli
- Department of Sciences, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy
| | - Viviana Trezza
- Department of Sciences, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy
| | - Paolo Ascenzi
- Interdepartmental Laboratory for Electron Microscopy, Roma Tre University, Via della Vasca Navale 79, I- 00146 Roma, Italy
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Prevotella intermedia produces two proteins homologous to Porphyromonas gingivalis HmuY but with different heme coordination mode. Biochem J 2020; 477:381-405. [PMID: 31899475 DOI: 10.1042/bcj20190607] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/20/2019] [Accepted: 01/02/2020] [Indexed: 02/07/2023]
Abstract
As part of the infective process, Porphyromonas gingivalis must acquire heme which is indispensable for life and enables the microorganism to survive and multiply at the infection site. This oral pathogenic bacterium uses a newly discovered novel hmu heme uptake system with a leading role played by the HmuY hemophore-like protein, responsible for acquiring heme and increasing virulence of this periodontopathogen. We demonstrated that Prevotella intermedia produces two HmuY homologs, termed PinO and PinA. Both proteins were produced at higher mRNA and protein levels when the bacterium grew under low-iron/heme conditions. PinO and PinA bound heme, but preferentially under reducing conditions, and in a manner different from that of the P. gingivalis HmuY. The analysis of the three-dimensional structures confirmed differences between apo-PinO and apo-HmuY, mainly in the fold forming the heme-binding pocket. Instead of two histidine residues coordinating heme iron in P. gingivalis HmuY, PinO and PinA could use one methionine residue to fulfill this function, with potential support of additional methionine residue/s. The P. intermedia proteins sequestered heme only from the host albumin-heme complex under reducing conditions. Our findings suggest that HmuY-like family might comprise proteins subjected during evolution to significant diversification, resulting in different heme coordination modes. The newer data presented in this manuscript on HmuY homologs produced by P. intermedia sheds more light on the novel mechanism of heme uptake, could be helpful in discovering their biological function, and in developing novel therapeutic approaches.
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Tannerella forsythia Tfo belongs to Porphyromonas gingivalis HmuY-like family of proteins but differs in heme-binding properties. Biosci Rep 2018; 38:BSR20181325. [PMID: 30266745 PMCID: PMC6200708 DOI: 10.1042/bsr20181325] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 09/10/2018] [Accepted: 09/20/2018] [Indexed: 12/16/2022] Open
Abstract
Porphyromonas gingivalis is considered the principal etiologic agent and keystone pathogen of chronic periodontitis. As an auxotrophic bacterium, it must acquire heme to survive and multiply at the infection site. P. gingivalis HmuY is the first member of a novel family of hemophore-like proteins. Bacterial heme-binding proteins usually use histidine-methionine or histidine-tyrosine residues to ligate heme-iron, whereas P. gingivalis HmuY uses two histidine residues. We hypothesized that other 'red complex' members, i.e. Tannerella forsythia and Treponema denticola might utilize similar heme uptake mechanisms to the P. gingivalis HmuY. Comparative and phylogenetic analyses suggested differentiation of HmuY homologs and low conservation of heme-coordinating histidine residues present in HmuY. The homologs were subjected to duplication before divergence of Bacteroidetes lineages, which could facilitate evolution of functional diversification. We found that T. denticola does not code an HmuY homolog. T. forsythia protein, termed as Tfo, binds heme, but preferentially in the ferrous form, and sequesters heme from the albumin-heme complex under reducing conditions. In agreement with that, the 3D structure of Tfo differs from that of HmuY in the folding of heme-binding pocket, containing two methionine residues instead of two histidine residues coordinating heme in HmuY. Heme binding to apo-HmuY is accompanied by movement of the loop carrying the His166 residue, closing the heme-binding pocket. Molecular dynamics simulations (MD) demonstrated that this conformational change also occurs in Tfo. In conclusion, our findings suggest that HmuY-like family might comprise proteins subjected during evolution to significant diversification, resulting in different heme-binding properties.
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Ascenzi P, Bocedi A, Gioia M, Fanali G, Fasano M, Coletta M. Warfarin inhibits allosterically the reductive nitrosylation of ferric human serum heme-albumin. J Inorg Biochem 2017; 177:63-75. [PMID: 28926756 DOI: 10.1016/j.jinorgbio.2017.08.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 08/30/2017] [Indexed: 12/31/2022]
Abstract
Human serum heme-albumin (HSA-heme-Fe) displays heme-based ligand binding and (pseudo-)enzymatic properties. Here, the effect of the prototypical drug warfarin on kinetics and thermodynamics of NO binding to ferric and ferrous HSA-heme-Fe (HSA-heme-Fe(III) and HSA-heme-Fe(II), respectively) and on the NO-mediated reductive nitrosylation of the heme-Fe atom is reported; data were obtained between pH5.5 and 9.5 at 20.0°C. Since warfarin is a common drug, its effect on the reactivity of HSA-heme-Fe represents a relevant issue in the pharmacological therapy management. The inhibition of NO binding to HSA-heme-Fe(III) and HSA-heme-Fe(II) as well as of the NO-mediated reductive nitrosylation of the heme-Fe(III) atom by warfarin has been ascribed to drug binding to the fatty acid binding site 2 (FA2), shifting allosterically the penta-to-six coordination equilibrium of the heme-Fe atom toward the low reactive species showing the six-coordinated metal center by His146 and Tyr161 residues. These data: (i) support the role of HSA-heme-Fe in trapping NO, (ii) highlight the modulation of the heme-Fe-based reactivity by drugs, and (iii) could be relevant for the modulation of HSA functions by drugs in vivo.
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Affiliation(s)
- Paolo Ascenzi
- Interdepartmental Laboratory for Electron Microscopy, Roma Tre University, I-00146 Roma, Italy.
| | - Alessio Bocedi
- Department of Chemical Sciences and Technology, University of Roma "Tor Vergata", I-00133 Roma, Italy
| | - Magda Gioia
- Department of Clinical Sciences and Translational Medicine, University of Roma "Tor Vergata", I-00133 Roma, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, I-70126 Bari, Italy
| | | | - Mauro Fasano
- Department of Science and High Technology, University of Insubria, I-21052 Busto Arsizio, VA, Italy; Neuroscience Research Center, University of Insubria, I-21052 Busto Arsizio, VA, Italy
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Roma "Tor Vergata", I-00133 Roma, Italy; Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, I-70126 Bari, Italy
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8
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Cao HL, Sun LH, Liu L, Li J, Tang L, Guo YZ, Mei QB, He JH, Yin DC. Structural consistency analysis of recombinant and wild-type human serum albumin. J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2016.07.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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9
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Biophysical characterization of the interaction of human albumin with an anionic porphyrin. Biochem Biophys Rep 2016; 7:295-302. [PMID: 28955918 PMCID: PMC5613655 DOI: 10.1016/j.bbrep.2016.07.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 06/16/2016] [Accepted: 07/14/2016] [Indexed: 11/21/2022] Open
Abstract
The manuscript describes the characterization of the interaction between meso-tetrakis(p-sulfonatophenyl)porphyrin (TSPP) and human serum albumin (HSA). TSPP is a candidate for the photosensitization of structural and functional changes in proteins while HSA provides both an excellent protein model and binding and functional characteristics that could be explored in future applications of the approach. A combination of optical spectroscopic techniques (e.g., fluorescence spectroscopy, fluorescence lifetime, circular dichroism, etc.) and computational docking simulations were applied to better characterize the TSPP/HSA interaction. Recent advances have revealed that the complex formed by TSPP and HSA has become potentially relevant to biomedical applications, biomaterials research and protein photosensitized engineering. The study has determined a likely location of the binding site that places TSPP at a site that overlaps partially with the low affinity site of ibuprofen and places one of the SO3− groups of the ligand in proximity of the Trp214 residue in HSA. The characterization will enable future studies aimed at photosensitizing non-native functions of HSA for biomedical and biomaterial applications. A novel protocol involving extensive dialysis and centrifugation eliminated aggregated protoporphyrins from the solution. Reliable FRET between Trp214 and the porphyrin ligands was established. FRET and docking simulations converge to a model consistent with experimental X-ray data. Photosensitization mediated by the porphyrin ligands prompts localized conformational changes in HSA.
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10
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Imatinib binding to human serum albumin modulates heme association and reactivity. Arch Biochem Biophys 2014; 560:100-12. [DOI: 10.1016/j.abb.2014.07.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 06/25/2014] [Accepted: 07/02/2014] [Indexed: 01/09/2023]
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Meneghini C, Leboffe L, Bionducci M, Fanali G, Meli M, Colombo G, Fasano M, Ascenzi P, Mobilio S. The five-to-six-coordination transition of ferric human serum heme-albumin is allosterically-modulated by ibuprofen and warfarin: a combined XAS and MD study. PLoS One 2014; 9:e104231. [PMID: 25153171 PMCID: PMC4143227 DOI: 10.1371/journal.pone.0104231] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 07/08/2014] [Indexed: 12/20/2022] Open
Abstract
Human serum albumin (HSA) is involved physiologically in heme scavenging; in turn, heme-albumin (HSA-heme-Fe) displays globin-like properties. Here, the allosteric effect of ibuprofen and warfarin on the local atomic structure around the ferric heme-Fe (heme-Fe(III)) atom of HSA-heme-Fe (HSA-heme-Fe(III)) has been probed by Fe-K edge X-ray absorption spectroscopy (XAS). The quantitative analysis of the Fe-K edge extended X-ray absorption fine structure (EXAFS) signals and modeling of the near edge (XANES) spectral features demonstrated that warfarin and ibuprofen binding modify the local structure of the heme-Fe(III). Combined XAS data analysis and targeted molecular dynamics (MD) simulations provided atomic resolution insights of protein structural rearrangements required to accommodate the heme-Fe(III) upon ibuprofen and warfarin binding. In the absence of drugs, the heme-Fe(III) atom is penta-coordinated having distorted 4+1 configuration made by the nitrogen atoms of the porphyrin ring and the oxygen phenoxy atom of the Tyr161 residue. MD simulations show that ibuprofen and warfarin association to the secondary fatty acid (FA) binding site 2 (FA2) induces a reorientation of domain I of HSA-heme-Fe(III), this leads to the redirection of the His146 residue providing an additional bond to the heme-Fe(III) atom, providing the 5+1 configuration. The comparison of Fe-K edge XANES spectra calculated using MD structures with those obtained experimentally confirms the reliability of the proposed structural model. As a whole, combining XAS and MD simulations it has been possible to provide a reliable model of the heme-Fe(III) atom coordination state and to understand the complex allosteric transition occurring in HSA-heme-Fe(III) upon ibuprofen and warfarin binding.
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Affiliation(s)
| | - Loris Leboffe
- Department of Sciences, Roma Tre University, Roma, Italy
- National Institute of Biostructures and Biosystems, Roma, Italy
| | | | - Gabriella Fanali
- Biomedical Research Division, Department of Theoretical and Applied Sciences, and Center of Neuroscience, University of Insubria, Busto Arsizio (VA), Italy
| | - Massimiliano Meli
- Institute for Molecular Recognition Chemistry, National Research Council, Milano, Italy
| | - Giorgio Colombo
- Institute for Molecular Recognition Chemistry, National Research Council, Milano, Italy
| | - Mauro Fasano
- Biomedical Research Division, Department of Theoretical and Applied Sciences, and Center of Neuroscience, University of Insubria, Busto Arsizio (VA), Italy
| | - Paolo Ascenzi
- National Institute of Biostructures and Biosystems, Roma, Italy
- Interdepartmental Laboratory of Electron Microscopy, Roma Tre University, Roma, Italy
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Ascenzi P, di Masi A, Tundo GR, Pesce A, Visca P, Coletta M. Nitrosylation mechanisms of Mycobacterium tuberculosis and Campylobacter jejuni truncated hemoglobins N, O, and P. PLoS One 2014; 9:e102811. [PMID: 25051055 PMCID: PMC4106858 DOI: 10.1371/journal.pone.0102811] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/23/2014] [Indexed: 01/19/2023] Open
Abstract
Truncated hemoglobins (trHbs) are widely distributed in bacteria and plants and have been found in some unicellular eukaryotes. Phylogenetic analysis based on protein sequences shows that trHbs branch into three groups, designated N (or I), O (or II), and P (or III). Most trHbs are involved in the O2/NO chemistry and/or oxidation/reduction function, permitting the survival of the microorganism in the host. Here, a detailed comparative analysis of kinetics and/or thermodynamics of (i) ferrous Mycobacterium tubertulosis trHbs N and O (Mt-trHbN and Mt-trHbO, respectively), and Campylobacter jejuni trHb (Cj-trHbP) nitrosylation, (ii) nitrite-mediated nitrosylation of ferrous Mt-trHbN, Mt-trHbO, and Cj-trHbP, and (iii) NO-based reductive nitrosylation of ferric Mt-trHbN, Mt-trHbO, and Cj-trHbP is reported. Ferrous and ferric Mt-trHbN and Cj-trHbP display a very high reactivity towards NO; however, the conversion of nitrite to NO is facilitated primarily by ferrous Mt-trHbN. Values of kinetic and/or thermodynamic parameters reflect specific trHb structural features, such as the ligand diffusion pathways to/from the heme, the heme distal pocket structure and polarity, and the ligand stabilization mechanisms. In particular, the high reactivity of Mt-trHbN and Cj-trHbP reflects the great ligand accessibility to the heme center by two protein matrix tunnels and the E7-path, respectively, and the penta-coordination of the heme-Fe atom. In contrast, the heme-Fe atom of Mt-trHbO the ligand accessibility to the heme center of Mt-trHbO needs large conformational readjustments, thus limiting the heme-based reactivity. These results agree with different roles of Mt-trHbN, Mt-trHbO, and Cj-trHbP in vivo.
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Affiliation(s)
- Paolo Ascenzi
- Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Roma, Italy
- * E-mail:
| | - Alessandra di Masi
- Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Roma, Italy
- Department of Sciences, University Roma Tre, Roma, Italy
| | - Grazia R. Tundo
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, Roma, Italy
- Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Bari, Italy
| | | | - Paolo Visca
- Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Roma, Italy
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Roma “Tor Vergata”, Roma, Italy
- Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Bari, Italy
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Warfarin modulates the nitrite reductase activity of ferrous human serum heme-albumin. J Biol Inorg Chem 2013; 18:939-46. [PMID: 24037275 DOI: 10.1007/s00775-013-1040-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 08/27/2013] [Indexed: 12/28/2022]
Abstract
Human serum heme-albumin (HSA-heme-Fe) displays reactivity and spectroscopic properties similar to those of heme proteins. Here, the nitrite reductase activity of ferrous HSA-heme-Fe [HSA-heme-Fe(II)] is reported. The value of the second-order rate constant for the reduction of [Formula: see text] to NO and the concomitant formation of nitrosylated HSA-heme-Fe(II) (i.e., k on) is 1.3 M(-1) s(-1) at pH 7.4 and 20 °C. Values of k on increase by about one order of magnitude for each pH unit decrease between pH 6.5 to 8.2, indicating that the reaction requires one proton. Warfarin inhibits the HSA-heme-Fe(II) reductase activity, highlighting the allosteric linkage between the heme binding site [also named the fatty acid (FA) binding site 1; FA1] and the drug-binding cleft FA2. The dissociation equilibrium constant for warfarin binding to HSA-heme-Fe(II) is (3.1 ± 0.4) × 10(-4) M at pH 7.4 and 20 °C. These results: (1) represent the first evidence for the [Formula: see text] reductase activity of HSA-heme-Fe(II), (2) highlight the role of drugs (e.g., warfarin) in modulating HSA(-heme-Fe) functions, and (3) strongly support the view that HSA acts not only as a heme carrier but also displays transient heme-based reactivity.
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Farooqi MJ, Penick MA, Negrete GR, Brancaleon L. Interaction of human serum albumin with novel 3,9-disubstituted perylenes. Protein J 2013; 32:493-504. [PMID: 23975144 PMCID: PMC3871871 DOI: 10.1007/s10930-013-9508-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Human serum albumin (HSA) has been used as a model for the binding of a number of different ligands, including polyaromatic hydrocarbons, to proteins. In this case we have investigated the interaction of HSA with a novel set of perylene derivatives. Di-substituted perylene analogues have been synthesized as potentially useful organic photovoltaic materials. Their photophysical properties may make them viable for fuel cell applications too. However, these molecules are poorly soluble especially in aqueous solvents. Binding to water-soluble proteins may provide a way to solubilize them. At the same time one can study whether the photophysical processes initiated by the irradiation of a perylene ligand can cause conformational changes to the host protein. With the present study we demonstrated that of the three perylene derivatives investigated only one, the dimethoxy analogue, has a significant affinity for HSA at a binding site near the bottom of the central cleft (in proximity of the Trp214 residue). The small affinity prevents any significant photoinduced changes to occur in the protein.
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Affiliation(s)
- Mohammed J. Farooqi
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
| | - Mark A. Penick
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, USA
| | - George R. Negrete
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, USA
| | - Lorenzo Brancaleon
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, USA
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