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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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Analysis of the HbpA Protein from Corynebacterium diphtheriae Clinical Isolates and Identification of a Putative Hemoglobin-Binding Site on HbpA. J Bacteriol 2022; 204:e0034922. [PMID: 36346227 PMCID: PMC9765017 DOI: 10.1128/jb.00349-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The Corynebacterium diphtheriae hemoglobin-binding protein HbpA is critical for the acquisition of iron from the hemoglobin-haptoglobin complex (Hb-Hp). Previous studies using C. diphtheriae strain 1737 showed that large aggregates formed by HbpA are associated with iron transport activity and enhanced binding to Hb-Hp; however, specific regions within HbpA required for Hb-Hp binding or iron uptake have not been identified. In this study, we characterized two clinical isolates from Austria, designated 07-18 and 09-15, which express HbpA proteins that share only 53% and 44% sequence identity, respectively, to the strain 1737 HbpA protein. The HbpA proteins expressed by the Austrian strains had functional and structural properties similar to those of the HbpA protein in strain 1737 despite the limited sequence similarity. These shared characteristics between the HbpA proteins included similar cellular localization, aggregate formation, and Hb and Hb-Hp binding. Additionally, the Austrian strains were able to acquire iron from Hb and Hb-Hp, and deletion of the hbpA gene from these two clinical isolates reduced their ability to use Hb-Hp as an iron source. A sequence comparison between the HbpA proteins from 1737 and the Austrian strains assisted in the identification of a putative Hb-binding site that shared similar characteristics with the Hb-binding regions in Staphylococcus aureus NEAT domains. Amino acid substitutions within this conserved Hb-binding region significantly reduced Hb and Hb-Hp binding and diminished the hemin-iron uptake function of HbpA. These findings represent important advances in our understanding of the interaction of HbpA with human hemoproteins. IMPORTANCE Hemoglobin (Hb) is the primary source of iron in humans, and the acquisition of hemin-iron from Hb is critical for many bacterial pathogens to infect and survive in the human host. In this study, we have examined the C. diphtheriae Hb-binding protein HbpA in two clinical isolates and show that these proteins, despite limited sequence similarity, are functionally equivalent to the previously described HbpA protein in strain 1737. A sequence comparison between these three strains led to the identification of a conserved Hb-binding site, which will further our understanding of how this novel protein functions in hemin-iron transport and, more generally, will expand our knowledge on how Hb interacts with proteins.
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Donegan RK. The role of host heme in bacterial infection. Biol Chem 2022; 403:1017-1029. [PMID: 36228088 DOI: 10.1515/hsz-2022-0192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 09/14/2022] [Indexed: 11/15/2022]
Abstract
Heme is an indispensable cofactor for almost all aerobic life, including the human host and many bacterial pathogens. During infection, heme and hemoproteins are the largest source of bioavailable iron, and pathogens have evolved various heme acquisition pathways to satisfy their need for iron and heme. Many of these pathways are regulated transcriptionally by intracellular iron levels, however, host heme availability and intracellular heme levels have also been found to regulate heme uptake in some species. Knowledge of these pathways has helped to uncover not only how these bacteria incorporate host heme into their metabolism but also provided insight into the importance of host heme as a nutrient source during infection. Within this review is covered multiple aspects of the role of heme at the host pathogen interface, including the various routes of heme biosynthesis, how heme is sequestered by the host, and how heme is scavenged by bacterial pathogens. Also discussed is how heme and hemoproteins alter the behavior of the host immune system and bacterial pathogens. Finally, some unanswered questions about the regulation of heme uptake and how host heme is integrated into bacterial metabolism are highlighted.
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Affiliation(s)
- Rebecca K Donegan
- Department of Chemistry, Barnard College, 3009 Broadway, New York, NY, 10027, USA
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Wu Z, Shao J, Zheng J, Liu B, Li Z, Shen N. A zero-sum game or an interactive frame? Iron competition between bacteria and humans in infection war. Chin Med J (Engl) 2022; 135:1917-1926. [PMID: 35830263 PMCID: PMC9746790 DOI: 10.1097/cm9.0000000000002233] [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] [Received: 01/04/2022] [Indexed: 11/26/2022] Open
Abstract
ABSTRACT Iron is an essential trace element for both humans and bacteria. It plays a vital role in life, such as in redox reactions and electron transport. Strict regulatory mechanisms are necessary to maintain iron homeostasis because both excess and insufficient iron are harmful to life. Competition for iron is a war between humans and bacteria. To grow, reproduce, colonize, and successfully cause infection, pathogens have evolved various mechanisms for iron uptake from humans, principally Fe 3+ -siderophore and Fe 2+ -heme transport systems. Humans have many innate immune mechanisms that regulate the distribution of iron and inhibit bacterial iron uptake to help resist bacterial invasion and colonization. Meanwhile, researchers have invented detection test strips and coupled antibiotics with siderophores to create tools that take advantage of this battle for iron, to help eliminate pathogens. In this review, we summarize bacterial and human iron metabolism, competition for iron between humans and bacteria, siderophore sensors, antibiotics coupled with siderophores, and related phenomena. We also discuss how competition for iron can be used for diagnosis and treatment of infection in the future.
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Affiliation(s)
- Zhenchao Wu
- Department of Pulmonary and Critical Care Medicine, Peking University Third Hospital, Beijing 100191, China
- Center for Infectious Diseases, Peking University Third Hospital, Beijing 100191, China
| | - Jiqi Shao
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Jiajia Zheng
- Department of Laboratory Medicine, Peking University Third Hospital, Beijing 100191, China
| | - Beibei Liu
- Department of Pulmonary and Critical Care Medicine, Peking University Third Hospital, Beijing 100191, China
| | - Zhiyuan Li
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Ning Shen
- Department of Pulmonary and Critical Care Medicine, Peking University Third Hospital, Beijing 100191, China
- Center for Infectious Diseases, Peking University Third Hospital, Beijing 100191, China
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Valenciano-Bellido S, Caaveiro JMM, Morante K, Sushko T, Nakakido M, Nagatoishi S, Tsumoto K. Structure and role of the linker domain of the iron surface-determinant protein IsdH in heme transportation in Staphylococcus aureus. J Biol Chem 2022; 298:101995. [PMID: 35500652 PMCID: PMC9163592 DOI: 10.1016/j.jbc.2022.101995] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 04/25/2022] [Accepted: 04/26/2022] [Indexed: 11/17/2022] Open
Abstract
Staphylococcus aureus is a major cause of deadly nosocomial infections, a severe problem fueled by the steady increase of resistant bacteria. The iron surface determinant (Isd) system is a family of proteins that acquire nutritional iron from the host organism, helping the bacterium to proliferate during infection, and therefore represents a promising antibacterial target. In particular, the surface protein IsdH captures hemoglobin (Hb) and acquires the heme moiety containing the iron atom. Structurally, IsdH comprises three distinctive NEAr-iron Transporter (NEAT) domains connected by linker domains. The objective of this study was to characterize the linker region between NEAT2 and NEAT3 from various biophysical viewpoints and thereby advance our understanding of its role in the molecular mechanism of heme extraction. We demonstrate the linker region contributes to the stability of the bound protein, likely influencing the flexibility and orientation of the NEAT3 domain in its interaction with Hb, but only exerts a modest contribution to the affinity of IsdH for heme. Based on these data, we suggest that the flexible nature of the linker facilitates the precise positioning of NEAT3 to acquire heme. In addition, we also found that residues His45 and His89 of Hb located in the heme transfer route toward IsdH do not play a critical role in the transfer rate-determining step. In conclusion, this study clarifies key elements of the mechanism of heme extraction of human Hb by IsdH, providing key insights into the Isd system and other protein systems containing NEAT domains.
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Affiliation(s)
| | - Jose M M Caaveiro
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo, Japan; Laboratory of Global Healthcare, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
| | - Koldo Morante
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Tatyana Sushko
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Makoto Nakakido
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo, Japan; Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
| | | | - Kouhei Tsumoto
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo, Japan; Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan; Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
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De Bei O, Marchetti M, Ronda L, Gianquinto E, Lazzarato L, Chirgadze DY, Hardwick SW, Cooper LR, Spyrakis F, Luisi BF, Campanini B, Bettati S. Cryo-EM structures of staphylococcal IsdB bound to human hemoglobin reveal the process of heme extraction. Proc Natl Acad Sci U S A 2022; 119:e2116708119. [PMID: 35357971 PMCID: PMC9168843 DOI: 10.1073/pnas.2116708119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 02/11/2022] [Indexed: 12/02/2022] Open
Abstract
Iron surface determinant B (IsdB) is a hemoglobin (Hb) receptor essential for hemic iron acquisition by Staphylococcus aureus. Heme transfer to IsdB is possible from oxidized Hb (metHb), but inefficient from Hb either bound to oxygen (oxyHb) or bound to carbon monoxide (HbCO), and encompasses a sequence of structural events that are currently poorly understood. By single-particle cryo-electron microscopy, we determined the structure of two IsdB:Hb complexes, representing key species along the heme extraction pathway. The IsdB:HbCO structure, at 2.9-Å resolution, provides a snapshot of the preextraction complex. In this early stage of IsdB:Hb interaction, the hemophore binds to the β-subunits of the Hb tetramer, exploiting a folding-upon-binding mechanism that is likely triggered by a cis/trans isomerization of Pro173. Binding of IsdB to α-subunits occurs upon dissociation of the Hb tetramer into α/β dimers. The structure of the IsdB:metHb complex reveals the final step of the extraction process, where heme transfer to IsdB is completed. The stability of the complex, both before and after heme transfer from Hb to IsdB, is influenced by isomerization of Pro173. These results greatly enhance current understanding of structural and dynamic aspects of the heme extraction mechanism by IsdB and provide insight into the interactions that stabilize the complex before the heme transfer event. This information will support future efforts to identify inhibitors of heme acquisition by S. aureus by interfering with IsdB:Hb complex formation.
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Affiliation(s)
- Omar De Bei
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
| | - Marialaura Marchetti
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
- Department of Medicine and Surgery, University of Parma, Parma 43126, Italy
| | - Luca Ronda
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
- Department of Medicine and Surgery, University of Parma, Parma 43126, Italy
- Institute of Biophysics, National Research Council, Pisa 56124, Italy
| | - Eleonora Gianquinto
- Department of Drug Science and Technology, University of Turin, Turin 10125, Italy
| | - Loretta Lazzarato
- Department of Drug Science and Technology, University of Turin, Turin 10125, Italy
| | - Dimitri Y. Chirgadze
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Steven W. Hardwick
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Lee R. Cooper
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Francesca Spyrakis
- Department of Drug Science and Technology, University of Turin, Turin 10125, Italy
| | - Ben F. Luisi
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
| | - Barbara Campanini
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
- Department of Food and Drug, University of Parma, Parma 43124, Italy
| | - Stefano Bettati
- Interdepartmental Center Biopharmanet-TEC, University of Parma, Parma 43124, Italy
- Department of Medicine and Surgery, University of Parma, Parma 43126, Italy
- Institute of Biophysics, National Research Council, Pisa 56124, Italy
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The Corynebacterium diphtheriae HbpA hemoglobin-binding protein contains a domain that is critical for hemoprotein-binding, cellular localization and function. J Bacteriol 2021; 203:e0019621. [PMID: 34370560 DOI: 10.1128/jb.00196-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The acquisition of hemin-iron from hemoglobin-haptoglobin (Hb-Hp) by Corynebacterium diphtheriae requires the iron-regulated surface proteins HtaA, ChtA, ChtC, and the recently identified Hb-Hp binding protein HbpA. We previously showed that a purified form of HbpA (HbpA-S), lacking the C-terminal region, was able to bind Hb-Hp. In this study, we show that the C-terminal region of HbpA significantly enhances binding to Hb-Hp. A purified form of HbpA that includes the C-terminal domain (HbpA-FL) exhibits much stronger binding to Hb-Hp than HbpA-S. Size exclusion chromatography (SEC) showed that HbpA-FL as well as HtaA-FL, ChtA-FL, and ChtC-FL exist as high molecular weight complexes, while HbpA-S is present as a monomer, indicating that the C-terminal region is required for formation of large aggregates. Growth studies showed that expression of HbpA-FL in the ΔhbpA mutant restored wild-type levels of growth in low-iron medium that contained Hb-Hp as the sole iron source, while HbpA-S failed to complement the ΔhbpA mutant. Protein localization studies in C. diphtheriae showed that HbpA-FL is present in both in the supernatant and in the membrane fractions, and that the C-terminal region is required for membrane anchoring. Purified HbpA-FL was able to enhance growth of the ΔhbpA mutant when added to culture medium that contained Hb-Hp as a sole iron source, suggesting that secreted HbpA is involved in the use of hemin-iron from Hb-Hp. These studies extend our understanding of this novel Hb-Hp binding protein in this important human pathogen. IMPORTANCE Hemoproteins, such as Hb, are an abundant source of iron in humans and are proposed to be required by numerous pathogens to cause disease. In this report, we expand on our previous studies in further defining the role of HbpA in hemin-iron acquisition in C. diphtheriae. HbpA is unique to C. diphtheriae, and appears to function unlike any previously described bacterial iron-regulated Hb- or Hb-Hp-binding protein. HbpA is both secreted and present in the membrane, and exists as a large aggregate that enhances its ability to bind Hb-Hp and promote hemin-iron uptake. Current studies with HbpA will increase our understanding of iron transport systems in C. diphtheriae.
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