1
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Macdonald R, Mahoney BJ, Soule J, Goring AK, Ford J, Loo JA, Cascio D, Clubb RT. The Shr receptor from Streptococcus pyogenes uses a cap and release mechanism to acquire heme-iron from human hemoglobin. Proc Natl Acad Sci U S A 2023; 120:e2211939120. [PMID: 36693107 PMCID: PMC9945957 DOI: 10.1073/pnas.2211939120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 12/19/2022] [Indexed: 01/25/2023] Open
Abstract
Streptococcus pyogenes (group A Streptococcus) is a clinically important microbial pathogen that requires iron in order to proliferate. During infections, S. pyogenes uses the surface displayed Shr receptor to capture human hemoglobin (Hb) and acquires its iron-laden heme molecules. Through a poorly understood mechanism, Shr engages Hb via two structurally unique N-terminal Hb-interacting domains (HID1 and HID2) which facilitate heme transfer to proximal NEAr Transporter (NEAT) domains. Based on the results of X-ray crystallography, small angle X-ray scattering, NMR spectroscopy, native mass spectrometry, and heme transfer experiments, we propose that Shr utilizes a "cap and release" mechanism to gather heme from Hb. In the mechanism, Shr uses the HID1 and HID2 modules to preferentially recognize only heme-loaded forms of Hb by contacting the edges of its protoporphyrin rings. Heme transfer is enabled by significant receptor dynamics within the Shr-Hb complex which function to transiently uncap HID1 from the heme bound to Hb's β subunit, enabling the gated release of its relatively weakly bound heme molecule and subsequent capture by Shr's NEAT domains. These dynamics may maximize the efficiency of heme scavenging by S. pyogenes, enabling it to preferentially recognize and remove heme from only heme-loaded forms of Hb that contain iron.
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Affiliation(s)
- Ramsay Macdonald
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Brendan J. Mahoney
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
- University of California, Los Angeles-United States Department of Energy Institute of Genomics and Proteomics, University of California, Los Angeles, CA90095
| | - Jess Soule
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Andrew K. Goring
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Jordan Ford
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Joseph A. Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
- University of California, Los Angeles-United States Department of Energy Institute of Genomics and Proteomics, University of California, Los Angeles, CA90095
- Molecular Biology Institute, University of California, Los Angeles, CA90095
| | - Duilio Cascio
- University of California, Los Angeles-United States Department of Energy Institute of Genomics and Proteomics, University of California, Los Angeles, CA90095
| | - Robert T. Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
- University of California, Los Angeles-United States Department of Energy Institute of Genomics and Proteomics, University of California, Los Angeles, CA90095
- Molecular Biology Institute, University of California, Los Angeles, CA90095
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2
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Huynh MS, Hooda Y, Li YR, Jagielnicki M, Lai CCL, Moraes TF. Reconstitution of surface lipoprotein translocation through the slam translocon. eLife 2022; 11:72822. [PMID: 35475756 PMCID: PMC9090332 DOI: 10.7554/elife.72822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Surface lipoproteins (SLPs) are peripherally attached to the outer leaflet of the outer membrane in many Gram-negative bacteria, playing significant roles in nutrient acquisition and immune evasion in the host. While the factors that are involved in the synthesis and delivery of SLPs in the inner membrane are well characterized, the molecular machinery required for the movement of SLPs to the surface are still not fully elucidated. In this study, we investigated the translocation of a SLP TbpB through a Slam1-dependent pathway. Using purified components, we developed an in vitro translocation assay where unfolded TbpB is transported through Slam1-containing proteoliposomes, confirming Slam1 as an outer membrane translocon. While looking to identify factors to increase translocation efficiency, we discovered the periplasmic chaperone Skp interacted with TbpB in the periplasm of Escherichia coli. The presence of Skp was found to increase the translocation efficiency of TbpB in the reconstituted translocation assays. A knockout of Skp in Neisseria meningitidis revealed that Skp is essential for functional translocation of TbpB to the bacterial surface. Taken together, we propose a pathway for surface destined lipoproteins, where Skp acts as a holdase for Slam-mediated TbpB translocation across the outer membrane.
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Affiliation(s)
- Minh Sang Huynh
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Yogesh Hooda
- MRC Laboratory of Molecular Biology, University of Cambridge, Cambridge, United Kingdom
| | - Yuzi Raina Li
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | | | | | - Trevor F Moraes
- Department of Biochemistry, University of Toronto, Toronto, Canada
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3
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Bateman TJ, Shah M, Ho TP, Shin HE, Pan C, Harris G, Fegan JE, Islam EA, Ahn SK, Hooda Y, Gray-Owen SD, Chen W, Moraes TF. A Slam-dependent hemophore contributes to heme acquisition in the bacterial pathogen Acinetobacter baumannii. Nat Commun 2021; 12:6270. [PMID: 34725337 PMCID: PMC8560813 DOI: 10.1038/s41467-021-26545-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 10/06/2021] [Indexed: 12/02/2022] Open
Abstract
Nutrient acquisition systems are often crucial for pathogen growth and survival during infection, and represent attractive therapeutic targets. Here, we study the protein machinery required for heme uptake in the opportunistic pathogen Acinetobacter baumannii. We show that the hemO locus, which includes a gene encoding the heme-degrading enzyme, is required for high-affinity heme acquisition from hemoglobin and serum albumin. The hemO locus includes a gene coding for a heme scavenger (HphA), which is secreted by a Slam protein. Furthermore, heme uptake is dependent on a TonB-dependent receptor (HphR), which is important for survival and/or dissemination into the vasculature in a mouse model of pulmonary infection. Our results indicate that A. baumannii uses a two-component receptor system for the acquisition of heme from host heme reservoirs.
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Affiliation(s)
- Thomas J Bateman
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Megha Shah
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Timothy Pham Ho
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | | | - Chuxi Pan
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Greg Harris
- National Research Council Canada, Human Health Therapeutics (HHT) Research Center, Ottawa, ON, Canada
| | - Jamie E Fegan
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Epshita A Islam
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Sang Kyun Ahn
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Yogesh Hooda
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Scott D Gray-Owen
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Wangxue Chen
- National Research Council Canada, Human Health Therapeutics (HHT) Research Center, Ottawa, ON, Canada
| | - Trevor F Moraes
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
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4
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An Exposed Outer Membrane Hemin-Binding Protein Facilitates Hemin Transport by a TonB-Dependent Receptor in Riemerella anatipestifer. Appl Environ Microbiol 2021; 87:e0036721. [PMID: 33990314 DOI: 10.1128/aem.00367-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Iron is an essential element for the replication of most bacteria, including Riemerella anatipestifer, a Gram-negative bacterial pathogen of ducks and other birds. R. anatipestifer utilizes hemoglobin-derived hemin as an iron source; however, the mechanism by which this bacterium acquires hemin from hemoglobin is largely unknown. Here, rhuA disruption was shown to impair iron utilization from duck hemoglobin in R. anatipestifer CH-1. Moreover, the putative lipoprotein RhuA was identified as a surface-exposed, outer membrane hemin-binding protein, but it could not extract hemin from duck hemoglobin. Mutagenesis studies showed that recombinant RhuAY144A, RhuAY177A, and RhuAH149A lost hemin-binding ability, suggesting that amino acid sites at tyrosine 144 (Y144), Y177, and histidine 149 (H149) are crucial for hemin binding. Furthermore, rhuR, the gene adjacent to rhuA, encodes a TonB2-dependent hemin transporter. The function of rhuA in duck hemoglobin utilization was abolished in the rhuR mutant strain, and recombinant RhuA was able to bind the cell surface of R. anatipestifer CH-1 ΔrhuA rather than R. anatipestifer CH-1 ΔrhuR ΔrhuA, indicating that RhuA associates with RhuR to function. The sequence of the RhuR-RhuA hemin utilization locus exhibits no similarity to those of characterized hemin transport systems. Thus, this locus is a novel hemin uptake locus with homologues distributed mainly in the Bacteroidetes phylum. IMPORTANCE In vertebrates, hemin from hemoglobin is an important iron source for infectious bacteria. Many bacteria can obtain hemin from hemoglobin, but the mechanisms of hemin acquisition from hemoglobin differ among bacteria. Moreover, most studies have focused on the mechanism of hemin acquisition from mammalian hemoglobin. In this study, we found that the RhuR-RhuA locus of R. anatipestifer CH-1, a duck pathogen, is involved in hemin acquisition from duck hemoglobin via a unique pathway. RhuA was identified as an exposed outer membrane hemin-binding protein, and RhuR was identified as a TonB2-dependent hemin transporter. Moreover, the function of RhuA in hemoglobin utilization is RhuR dependent and not vice versa. The homologues of RhuR and RhuA are widely distributed in bacteria in marine environments, animals, and plants, representing a novel hemin transportation system of Gram-negative bacteria. This study not only was important for understanding hemin uptake in R. anatipestifer but also enriched the knowledge about the hemin transportation pathway in Gram-negative bacteria.
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5
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Cole GB, Bateman TJ, Moraes TF. The surface lipoproteins of gram-negative bacteria: Protectors and foragers in harsh environments. J Biol Chem 2021; 296:100147. [PMID: 33277359 PMCID: PMC7857515 DOI: 10.1074/jbc.rev120.008745] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 12/02/2020] [Accepted: 12/04/2020] [Indexed: 11/06/2022] Open
Abstract
Gram-negative pathogens are enveloped by an outer membrane that serves as a double-edged sword: On the one hand, it provides a layer of protection for the bacterium from environmental insults, including other bacteria and the host immune system. On the other hand, it restricts movement of vital nutrients into the cell and provides a plethora of antigens that can be detected by host immune systems. One strategy used to overcome these limitations is the decoration of the outer surface of gram-negative bacteria with proteins tethered to the outer membrane through a lipid anchor. These surface lipoproteins (SLPs) fulfill critical roles in immune evasion and nutrient acquisition, but as more bacterial genomes are sequenced, we are beginning to discover their prevalence and their different roles and mechanisms and importantly how we can exploit them as antimicrobial targets. This review will focus on representative SLPs that gram-negative bacteria use to overcome host innate immunity, specifically the areas of nutritional immunity and complement system evasion. We elaborate on the structures of some notable SLPs required for binding target molecules in hosts and how this information can be used alongside bioinformatics to understand mechanisms of binding and in the discovery of new SLPs. This information provides a foundation for the development of therapeutics and the design of vaccine antigens.
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Affiliation(s)
- Gregory B Cole
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Thomas J Bateman
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Trevor F Moraes
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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6
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Hu J, Benny P, Wang M, Ma Y, Lambertini L, Peter I, Xu Y, Lee MJ. Intrauterine Growth Restriction Is Associated with Unique Features of the Reproductive Microbiome. Reprod Sci 2020; 28:828-837. [PMID: 33107014 DOI: 10.1007/s43032-020-00374-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 10/21/2020] [Indexed: 10/23/2022]
Abstract
Intrauterine growth restriction (IUGR) is an obstetrical complication with an increased risk of perinatal mortality and morbidity. The uterus, once considered to be a sterile environment, has now been described in recent microbiome studies to harbor diverse commensal placenta microbiota, as well as potentially pathogenic flora known to cause infection. Therefore, in this pilot study, we tested whether IUGR was associated with changes to the reproductive microbiome. The reproductive microbiome was surveyed using 16S sequencing (20 IUGR, 20 controls). Alpha and beta diversity were compared, and differential taxa features associated with IUGR were identified. Microbial screening of the placenta demonstrated a diverse range of flora predominantly including Proteobacteria, Fusobacteria, Firmicutes, and Bacteroidetes. Neither alpha- nor beta-diversity was significantly different by IUGR status. However, at the taxa level, IUGR patients had significantly higher prevalence of Neisseriaceae, mucosal β-hemolytic bacteria known to uptake iron-bound host proteins including hemoglobin. Moreover, the increase in anaerobic bacteria such as Desulfovibrio reflects the emergence of a hypoxic environment in the IUGR placenta. Further analysis of the reproductive microbiome of IUGR samples showed lower levels of H202-producing Bifidobacterium and Lactobacillus that switch from respiration to fermentation, a less energetic metabolic process, when oxygen levels decrease. Source tracking analysis showed that the placental microbial contents were predominantly contributed from an oral source, as compared to a gut or vaginal source. Our results suggest that the reproductive microbiome profiles may, in the future, constitute potential biomarkers for fetal health during pregnancy, while Neisseriaceae may constitute promising therapeutic targets for IUGR treatment.
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Affiliation(s)
- Jianzhong Hu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Paula Benny
- Department of Obstetrics, Gynecology and Women's Health, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Michelle Wang
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Washington University at St. Louis, Saint Louis, MO, USA
| | - Yula Ma
- Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Luca Lambertini
- Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Inga Peter
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Yajuan Xu
- The Third Affiliated Hospital of Zhangzhou University, Zhengzhou, Henan, China
| | - Men-Jean Lee
- Department of Obstetrics, Gynecology and Women's Health, University of Hawaii at Manoa, Honolulu, HI, USA.
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7
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Maurakis S, Cornelissen CN. Metal-Limited Growth of Neisseria gonorrhoeae for Characterization of Metal-Responsive Genes and Metal Acquisition from Host Ligands. J Vis Exp 2020. [PMID: 32202529 DOI: 10.3791/60903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Trace metals such as iron and zinc are vital nutrients known to play key roles in prokaryotic processes including gene regulation, catalysis, and protein structure. Metal sequestration by hosts often leads to metal limitation for the bacterium. This limitation induces bacterial gene expression whose protein products allow bacteria to overcome their metal-limited environment. Characterization of such genes is challenging. Bacteria must be grown in meticulously prepared media that allows sufficient access to nutritional metals to permit bacterial growth while maintaining a metal profile conducive to achieving expression of the aforementioned genes. As such, a delicate balance must be established for the concentrations of these metals. Growing a nutritionally fastidious organism such as Neisseria gonorrhoeae, which has evolved to survive only in the human host, adds an additional level of complexity. Here, we describe the preparation of a defined metal-limited medium sufficient to allow gonococcal growth and the desired gene expression. This method allows the investigator to chelate iron and zinc from undesired sources while supplementing the media with defined sources of iron or zinc, whose preparation is also described. Finally, we outline three experiments that utilize this media to help characterize the protein products of metal-regulated gonococcal genes.
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8
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Yadav R, Noinaj N, Ostan N, Moraes T, Stoudenmire J, Maurakis S, Cornelissen CN. Structural Basis for Evasion of Nutritional Immunity by the Pathogenic Neisseriae. Front Microbiol 2020; 10:2981. [PMID: 31998268 PMCID: PMC6965322 DOI: 10.3389/fmicb.2019.02981] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 12/10/2019] [Indexed: 12/17/2022] Open
Abstract
The pathogenic Neisseria species are human-adapted pathogens that cause quite distinct diseases. Neisseria gonorrhoeae causes the common sexually transmitted infection gonorrhea, while Neisseria meningitidis causes a potentially lethal form of bacterial meningitis. During infection, both pathogens deploy a number of virulence factors in order to thrive in the host. The focus of this review is on the outer membrane transport systems that enable the Neisseriae to utilize host-specific nutrients, including metal-binding proteins such as transferrin and calprotectin. Because acquisition of these critical metals is essential for growth and survival, understanding the structures of receptor-ligand complexes may be an important step in developing preventative or therapeutic strategies focused on thwarting these pathogens. Much can also be learned by comparing structures with antigenic diversity among the transporter sequences, as conserved functional domains in these essential transporters could represent the pathogens' "Achilles heel." Toward this goal, we present known or modeled structures for the transport systems produced by the pathogenic Neisseria species, overlapped with sequence diversity derived by comparing hundreds of neisserial protein sequences. Given the concerning increase in N. gonorrhoeae incidence and antibiotic resistance, these outer membrane transport systems appear to be excellent targets for new therapies and preventative vaccines.
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Affiliation(s)
- Ravi Yadav
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, United States
| | - Nicholas Noinaj
- Markey Center for Structural Biology, Department of Biological Sciences, Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, United States
| | - Nicholas Ostan
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Trevor Moraes
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Julie Stoudenmire
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, United States
| | - Stavros Maurakis
- Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, United States
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9
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Latham RD, Torrado M, Atto B, Walshe JL, Wilson R, Guss JM, Mackay JP, Tristram S, Gell DA. A heme-binding protein produced by Haemophilus haemolyticus inhibits non-typeable Haemophilus influenzae. Mol Microbiol 2019; 113:381-398. [PMID: 31742788 DOI: 10.1111/mmi.14426] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 11/14/2019] [Accepted: 11/15/2019] [Indexed: 01/02/2023]
Abstract
Commensal bacteria serve as an important line of defense against colonisation by opportunisitic pathogens, but the underlying molecular mechanisms remain poorly explored. Here, we show that strains of a commensal bacterium, Haemophilus haemolyticus, make hemophilin, a heme-binding protein that inhibits growth of the opportunistic pathogen, non-typeable Haemophilus influenzae (NTHi) in culture. We purified the NTHi-inhibitory protein from H. haemolyticus and identified the hemophilin gene using proteomics and a gene knockout. An x-ray crystal structure of recombinant hemophilin shows that the protein does not belong to any of the known heme-binding protein folds, suggesting that it evolved independently. Biochemical characterisation shows that heme can be captured in the ferrous or ferric state, and with a variety of small heme-ligands bound, suggesting that hemophilin could function under a range of physiological conditions. Hemophilin knockout bacteria show a limited capacity to utilise free heme for growth. Our data suggest that hemophilin is a hemophore and that inhibition of NTHi occurs by heme starvation, raising the possibility that competition from hemophilin-producing H. haemolyticus could antagonise NTHi colonisation in the respiratory tract.
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Affiliation(s)
- Roger D Latham
- School of Medicine, University of Tasmania, Hobart, Australia
| | - Mario Torrado
- School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
| | - Brianna Atto
- School of Health Sciences, University of Tasmania, Launceston, Australia
| | - James L Walshe
- School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
| | - Richard Wilson
- Central Science Laboratory, University of Tasmania, Hobart, Australia
| | - J Mitchell Guss
- School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
| | - Joel P Mackay
- School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
| | - Stephen Tristram
- School of Health Sciences, University of Tasmania, Launceston, Australia
| | - David A Gell
- School of Medicine, University of Tasmania, Hobart, Australia
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10
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Hu F, Xue Y, Guo C, Liu J, Mao S. The response of ruminal fermentation, epithelium-associated microbiota, and epithelial barrier function to severe feed restriction in pregnant ewes. J Anim Sci 2019; 96:4293-4305. [PMID: 30272228 DOI: 10.1093/jas/sky306] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 07/28/2018] [Indexed: 12/13/2022] Open
Abstract
The objective of this study was to evaluate the changes in the ruminal fermentation, epithelium-associated microbiota, and ruminal epithelial barrier function in response to severe feed restriction (SFR) in pregnant ewes. Sixteen pregnant ewes (108 d of gestation) were randomly blocked and assigned to 1 of 2 treatments: control (CON, n = 8) and SFR (n = 8). Ewes were fed a common diet with a 60:40 forage to concentrate ratio for 7-d baseline period followed by a SFR challenge period. Ewes on the SFR treatment were restricted to 30% of the base for 15 d. At the end of the experimental period, all animals were slaughtered and then ruminal contents and ruminal epithelial tissue were collected. Results showed that ruminal pH was greater in SFR group (P = 0.040) compared with CON group, while SFR decreased (P < 0.05) the concentrations of ruminal acetate, propionate, butyrate, and total volatile fatty acid. A plot of principal coordinate analysis and analysis of molecular variance revealed that the composition of ruminal epithelial bacterial communities in the CON group was distinct from that of the ruminal epithelial microbiome in the SFR animals. At the genus level, SFR increased the abundance of unclassified Neisseriaceae, Comamonas, and Papillibacter, and decreased the proportion of Howardella, Desulfobulbus, and Suttonella (P < 0.05) compared with CON group. The metagenome of ruminal epithelium-associated microbiota predicted by PICRUSt revealed that the SFR significantly affected 14 metabolic pathways, and 9 were significantly enriched in the SFR group. In particular, SFR markedly increased relative abundances of dominant gene families involved in amino acid metabolism (P = 0.003), cellular processes and signaling (P = 0.021), and lipid metabolism (P = 0.001). The real-time PCR results showed SFR decreased the mRNA expression of IL-10 (P = 0.003) and upregulated the mRNA expression of IL-6 (P = 0.003) and TLR4 (P = 0.021). The mRNA expression of Claudin-1 (P = 0.001) and ZO-1 (P = 0.009) were lower in the SFR group compared with the CON group. Generally, our data suggest that SFR decreased most ruminal fermentation parameters, altered the composition of rumen epithelium-associated microbiota, and compromised the barrier function of rumen epithelium. These findings are of great importance for understanding the alteration in the rumen function following SFR in pregnant ewes.
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Affiliation(s)
- Fan Hu
- Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Yanfeng Xue
- Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Changzheng Guo
- Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Junhua Liu
- Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Shengyong Mao
- Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
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11
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Macdonald R, Cascio D, Collazo MJ, Phillips M, Clubb RT. The Streptococcus pyogenes Shr protein captures human hemoglobin using two structurally unique binding domains. J Biol Chem 2018; 293:18365-18377. [PMID: 30301765 DOI: 10.1074/jbc.ra118.005261] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/03/2018] [Indexed: 12/19/2022] Open
Abstract
In order to proliferate and mount an infection, many bacterial pathogens need to acquire iron from their host. The most abundant iron source in the body is the oxygen transporter hemoglobin (Hb). Streptococcus pyogenes, a potentially lethal human pathogen, uses the Shr protein to capture Hb on the cell surface. Shr is an important virulence factor, yet the mechanism by which it captures Hb and acquires its heme is not well-understood. Here, we show using NMR and biochemical methods that Shr binds Hb using two related modules that were previously defined as domains of unknown function (DUF1533). These hemoglobin-interacting domains (HIDs), called HID1 and HID2, are autonomously folded and independently bind Hb. The 1.5 Å resolution crystal structure of HID2 revealed that it is a structurally unique Hb-binding domain. Mutagenesis studies revealed a conserved tyrosine in both HIDs that is essential for Hb binding. Our biochemical studies indicate that HID2 binds Hb with higher affinity than HID1 and that the Hb tetramer is engaged by two Shr receptors. NMR studies reveal the presence of a third autonomously folded domain between HID2 and a heme-binding NEAT1 domain, suggesting that this linker domain may position NEAT1 near Hb for heme capture.
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Affiliation(s)
- Ramsay Macdonald
- From the Department of Chemistry and Biochemistry,; UCLA-DOE Institute of Genomics and Proteomics and
| | | | | | | | - Robert T Clubb
- From the Department of Chemistry and Biochemistry,; UCLA-DOE Institute of Genomics and Proteomics and; Molecular Biology Institute, UCLA, Los Angeles, California 90095.
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12
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Mozzi A, Forni D, Clerici M, Cagliani R, Sironi M. The Diversity of Mammalian Hemoproteins and Microbial Heme Scavengers Is Shaped by an Arms Race for Iron Piracy. Front Immunol 2018; 9:2086. [PMID: 30271410 PMCID: PMC6142043 DOI: 10.3389/fimmu.2018.02086] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 08/23/2018] [Indexed: 11/13/2022] Open
Abstract
Iron is an essential micronutrient for most living species. In mammals, hemoglobin (Hb) stores more than two thirds of the body's iron content. In the bloodstream, haptoglobin (Hp) and hemopexin (Hpx) sequester free Hb or heme. Pathogenic microorganisms usually acquire iron from their hosts and have evolved complex systems of iron piracy to circumvent nutritional immunity. Herein, we performed an evolutionary analysis of genes coding for mammalian heme-binding proteins and heme-scavengers in pathogen species. The underlying hypothesis is that these molecules are engaged in a molecular arms race. We show that positive selection drove the evolution of mammalian Hb and Hpx. Positively selected sites in Hb are located at the interaction surface with Neisseria meningitidis heme scavenger HpuA and with Staphylococcus aureus iron-regulated surface determinant B (IsdB). In turn, positively selected sites in HpuA and IsdB are located in the flexible protein regions that contact Hb. A residue in Hb (S45H) was also selected on the Caprinae branch. This site stabilizes the interaction with Trypanosoma brucei hemoglobin-haptoglobin (HbHp) receptor (TbHpHbR), a molecule that also mediates trypanosome lytic factor (TLF) entry. In TbHpHbR, positive selection drove the evolution of a variant (L210S) which allows evasion from TLF but reduces affinity for HbHp. Finally, selected sites in Hpx are located at the interaction surface with the Haemophilus influenzae hemophore HxuA, which in turn displays fast evolving sites at the Hpx-binding interface. These results shed light into host-pathogens conflicts and establish the importance of nutritional immunity as an evolutionary force.
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Affiliation(s)
- Alessandra Mozzi
- Scientific Institute, IRCCS E. Medea, Bioinformatics, Lecco, Italy
| | - Diego Forni
- Scientific Institute, IRCCS E. Medea, Bioinformatics, Lecco, Italy
| | - Mario Clerici
- Department of Physiopathology and Transplantation, University of Milan, Milan, Italy.,Don C. Gnocchi Foundation ONLUS, IRCCS, Milan, Italy
| | - Rachele Cagliani
- Scientific Institute, IRCCS E. Medea, Bioinformatics, Lecco, Italy
| | - Manuela Sironi
- Scientific Institute, IRCCS E. Medea, Bioinformatics, Lecco, Italy
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Ejiofor OS, Ajunwa OM, Ezeudu CE, Emechebe GO, Okeke KN, Ifezulike CC, Ekejindu IM, Okoyeh JN, Osuala EO, Oli AN. The Bacteriology and Its Virulence Factors in Neonatal Infections: Threats to Child Survival Strategies. J Pathog 2018; 2018:4801247. [PMID: 30112215 PMCID: PMC6077539 DOI: 10.1155/2018/4801247] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/23/2018] [Accepted: 05/19/2018] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Neonatal infection refers to the infection of the newborn during the first twenty-eight days of life. It is one of the causes of infant morbidity and mortality worldwide. The aim of the study is to determine the relative contribution of the different pathogens to the overall disease burden. It will also determine the mechanisms of virulence of these pathogens that cause neonatal infections at Chukwuemeka Odumegwu Ojukwu University Teaching Hospital (COOUTH), Awka. METHODS Biological samples were collected from 30 neonates admitted at the special care baby unit (SCBU) of COOUTH and cultured using selective media and nutrient agar. The isolates were identified using microbiological and biochemical tests. The antibiogram study was determined using Kirby-Bauer disc diffusion method on Mueller Hinton Agar. Several methods previously reported in literature were used for the characterization of the virulence factors. RESULTS From the 30 blood samples collected, Pseudomonas spp. (19.7%), Escherichia coli (23%), Salmonella spp. (24.6%), and Staphylococcus aureus (32.8%) were isolated. Male to female ratio of study population was 1.5: 1. The isolates were 100 % resistant to ticarcillin, cephalothin, ceftazidime, and cefuroxime but appreciably susceptible to only levofloxacin (88.85%). They were moderately susceptible to ceftriaxone/sulbactam (39.05%) and azithromycin (26.46%). Common virulence factors identified among the isolates (up to 90 %) were hemolysin, biofilm formation, and acid resistance. Less common virulence factors were proteases (50 %), deoxyribonucleases (50 %), enterotoxins (63%), and lipopolysaccharide (70%). The virulence factors were found mostly among the S. aureus isolates. CONCLUSIONS Pseudomonas spp., Escherichia coli, Salmonella spp., and Staphylococcus aureus were implicated in neonatal infections in the center and most of them were resistant to conventional antibiotics. The organisms showed marked virulence and multidrug resistance properties. Levofloxacin, a fluoroquinolone, had superior activity on the isolates compared to other antibiotics used in the study.
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Affiliation(s)
- Obiora Shedrach Ejiofor
- Department of Pediatrics, Chukwuemeka Odumegwu Ojukwu University, Awka, Anambra State, Nigeria
| | - Onyinye Mercy Ajunwa
- Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, Agulu, Nnamdi Azikiwe University, Anambra State, Nigeria
| | - Chijioke Elias Ezeudu
- Department of Pediatrics, College of Health Sciences, Faculty of Medicine, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria
| | - George Ogonna Emechebe
- Department of Pediatrics, Chukwuemeka Odumegwu Ojukwu University, Awka, Anambra State, Nigeria
| | - Kenneth Nchekwube Okeke
- Department of Pediatrics, Chukwuemeka Odumegwu Ojukwu University, Awka, Anambra State, Nigeria
| | | | - Ifeoma Mercy Ekejindu
- Department of Medical Laboratory Science, Faculty of Health Science and Technology, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria
| | - Jude Nnaemeka Okoyeh
- Department of Clinical Laboratory Science, School of Health Sciences, Winston-Salem State University, Winston-Salem, NC, USA
| | - Eunice Ogonna Osuala
- Department of Nursing Sciences, Faculty of Health Science and Technology, Nnamdi Azikiwe University, Nnewi Campus, Nigeria
| | - Angus Nnamdi Oli
- Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, Agulu, Nnamdi Azikiwe University, Anambra State, Nigeria
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14
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Murphey AC, Mavridou DAI, Hodgkin J, Ferguson SJ. The heme auxotroph Caenorhabditis elegans can cleave the thioether bonds of c-type cytochromes. FEBS Lett 2018; 592:928-938. [PMID: 29430660 DOI: 10.1002/1873-3468.13006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/26/2018] [Accepted: 01/26/2018] [Indexed: 11/08/2022]
Abstract
Heme is essential and synthesized via highly regulated processes. For this reason, most organisms strive to recycle it or acquire it from their environment. When heme is bound to proteins noncovalently, degradation of the polypeptide is sufficient to release it. However, in some hemoproteins, such as c-type cytochromes, heme is covalently bound to the protein backbone. We use the heme auxotroph Caenorhabditis elegans to investigate if cytochromes c can be a heme source, and we show that this organism must encode a novel system which specifically cleaves the thioether bonds of c-type cytochromes. We also find that at limiting heme concentrations, while somatic tissues develop normally the germline fails to proliferate, suggesting the presence of a heme-sensing checkpoint in C. elegans.
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Affiliation(s)
| | - Despoina A I Mavridou
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, Kensington, UK
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15
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Tommassen J, Arenas J. Biological Functions of the Secretome of Neisseria meningitidis. Front Cell Infect Microbiol 2017; 7:256. [PMID: 28670572 PMCID: PMC5472700 DOI: 10.3389/fcimb.2017.00256] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 05/29/2017] [Indexed: 11/13/2022] Open
Abstract
Neisseria meningitidis is a Gram-negative bacterial pathogen that normally resides as a commensal in the human nasopharynx but occasionally causes disease with high mortality and morbidity. To interact with its environment, it transports many proteins across the outer membrane to the bacterial cell surface and into the extracellular medium for which it deploys the common and well-characterized autotransporter, two-partner and type I secretion mechanisms, as well as a recently discovered pathway for the surface exposure of lipoproteins. The surface-exposed and secreted proteins serve roles in host-pathogen interactions, including adhesion to host cells and extracellular matrix proteins, evasion of nutritional immunity imposed by iron-binding proteins of the host, prevention of complement activation, neutralization of antimicrobial peptides, degradation of immunoglobulins, and permeabilization of epithelial layers. Furthermore, they have roles in interbacterial interactions, including the formation and dispersal of biofilms and the suppression of the growth of bacteria competing for the same niche. Here, we will review the protein secretion systems of N. meningitidis and focus on the functions of the secreted proteins.
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Affiliation(s)
- Jan Tommassen
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht UniversityUtrecht, Netherlands
| | - Jesús Arenas
- Department of Molecular Microbiology and Institute of Biomembranes, Utrecht UniversityUtrecht, Netherlands
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16
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Hooda Y, Lai CCL, Moraes TF. Identification of a Large Family of Slam-Dependent Surface Lipoproteins in Gram-Negative Bacteria. Front Cell Infect Microbiol 2017; 7:207. [PMID: 28620585 PMCID: PMC5449769 DOI: 10.3389/fcimb.2017.00207] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/09/2017] [Indexed: 02/01/2023] Open
Abstract
The surfaces of many Gram-negative bacteria are decorated with soluble proteins anchored to the outer membrane via an acylated N-terminus; these proteins are referred to as surface lipoproteins or SLPs. In Neisseria meningitidis, SLPs such as transferrin-binding protein B (TbpB) and factor-H binding protein (fHbp) are essential for host colonization and infection because of their essential roles in iron acquisition and immune evasion, respectively. Recently, we identified a family of outer membrane proteins called Slam (Surface lipoprotein assembly modulator) that are essential for surface display of neisserial SLPs. In the present study, we performed a bioinformatics analysis to identify 832 Slam related sequences in 638 Gram-negative bacterial species. The list included several known human pathogens, many of which were not previously reported to possess SLPs. Hypothesizing that genes encoding SLP substrates of Slams may be present in the same gene cluster as the Slam genes, we manually curated neighboring genes for 353 putative Slam homologs. From our analysis, we found that 185 (~52%) of the 353 putative Slam homologs are located adjacent to genes that encode a protein with an N-terminal lipobox motif. This list included genes encoding previously reported SLPs in Haemophilus influenzae and Moraxella catarrhalis, for which we were able to show that the neighboring Slams are necessary and sufficient to display these lipoproteins on the surface of Escherichia coli. To further verify the authenticity of the list of predicted SLPs, we tested the surface display of one such Slam-adjacent protein from Pasteurella multocida, a zoonotic pathogen. A robust Slam-dependent display of the P. multocida protein was observed in the E. coli translocation assay indicating that the protein is a Slam-dependent SLP. Based on multiple sequence alignments and domain annotations, we found that an eight-stranded beta-barrel domain is common to all the predicted Slam-dependent SLPs. These findings suggest that SLPs with a TbpB-like fold are found widely in Proteobacteria where they exist with their interaction partner Slam. In the future, SLPs found in pathogenic bacteria can be investigated for their role in virulence and may also serve as candidates for vaccine development.
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Affiliation(s)
- Yogesh Hooda
- Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - Christine C L Lai
- Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - Trevor F Moraes
- Department of Biochemistry, University of TorontoToronto, ON, Canada
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17
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Transition metals at the host-pathogen interface: how Neisseria exploit human metalloproteins for acquiring iron and zinc. Essays Biochem 2017; 61:211-223. [PMID: 28487398 DOI: 10.1042/ebc20160084] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/06/2017] [Accepted: 03/13/2017] [Indexed: 12/17/2022]
Abstract
Transition metals are essential nutrients for all organisms and important players in the host-microbe interaction. During bacterial infection, a tug-of-war between the host and microbe for nutrient metals occurs: the host innate immune system responds to the pathogen by reducing metal availability and the pathogen tries to outmaneuver this response. The outcome of this competition, which involves metal-sequestering host-defense proteins and microbial metal acquisition machinery, is an important determinant for whether infection occurs. One strategy bacterial pathogens employ to overcome metal restriction involves hijacking abundant host metalloproteins. The obligate human pathogens Neisseria meningitidis and N. gonorrhoeae express TonB-dependent transport systems that capture human metalloproteins, extract the bound metal ions, and deliver these nutrients into the bacterial cell. This review highlights structural and mechanistic investigations that provide insights into how Neisseria acquire iron from the Fe(III)-transport protein transferrin (TF), the Fe(III)-chelating host-defense protein lactoferrin (LF), and the oxygen-transport protein hemoglobin (Hb), and obtain zinc from the metal-sequestering antimicrobial protein calprotectin (CP).
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18
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Abstract
Iron is essential for the survival of most bacteria but presents a significant challenge given its limited bioavailability. Furthermore, the toxicity of iron combined with the need to maintain physiological iron levels within a narrow concentration range requires sophisticated systems to sense, regulate, and transport iron. Most bacteria have evolved mechanisms to chelate and transport ferric iron (Fe3+) via siderophore receptor systems, and pathogenic bacteria have further lowered this barrier by employing mechanisms to utilize the host's hemoproteins. Once internalized, heme is cleaved by both oxidative and nonoxidative mechanisms to release iron. Heme, itself a lipophilic and toxic molecule, presents a significant challenge for transport into the cell. As such, pathogenic bacteria have evolved sophisticated cell surface signaling and transport systems to obtain heme from the host. In this review, we summarize the structure and function of the heme-sensing and transport systems of pathogenic bacteria and the potential of these systems as antimicrobial targets.
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Affiliation(s)
- Weiliang Huang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201;
| | - Angela Wilks
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201;
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19
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Diverse structural approaches to haem appropriation by pathogenic bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:422-433. [PMID: 28130069 DOI: 10.1016/j.bbapap.2017.01.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/16/2017] [Accepted: 01/23/2017] [Indexed: 11/24/2022]
Abstract
The critical need for iron presents a challenge for pathogenic bacteria that must survive in an environment bereft of accessible iron due to a natural low bioavailability and their host's nutritional immunity. Appropriating haem, either direct from host haemoproteins or by secreting haem-scavenging haemophores, is one way pathogenic bacteria can overcome this challenge. After capturing their target, haem appropriation systems must remove haem from a high-affinity binding site (on the host haemoprotein or bacterial haemophore) and transfer it to a binding site of lower affinity on a bacterial receptor. Structural information is now available to show how, using a combination of induced structural changes and steric clashes, bacteria are able to extract haem from haemophores, haemopexin and haemoglobin. This review focuses on structural descriptions of these bacterial haem acquisition systems, summarising how they bind haem and their target haemoproteins with particularly emphasis on the mechanism of haem extraction.
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20
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Grabe GJ, Zhang Y, Przydacz M, Rolhion N, Yang Y, Pruneda JN, Komander D, Holden DW, Hare SA. The Salmonella Effector SpvD Is a Cysteine Hydrolase with a Serovar-specific Polymorphism Influencing Catalytic Activity, Suppression of Immune Responses, and Bacterial Virulence. J Biol Chem 2016; 291:25853-25863. [PMID: 27789710 PMCID: PMC5207060 DOI: 10.1074/jbc.m116.752782] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/26/2016] [Indexed: 12/02/2022] Open
Abstract
Many bacterial pathogens secrete virulence (effector) proteins that interfere with immune signaling in their host. SpvD is a Salmonella enterica effector protein that we previously demonstrated to negatively regulate the NF-κB signaling pathway and promote virulence of S. enterica serovar Typhimurium in mice. To shed light on the mechanistic basis for these observations, we determined the crystal structure of SpvD and show that it adopts a papain-like fold with a characteristic cysteine-histidine-aspartate catalytic triad comprising Cys-73, His-162, and Asp-182. SpvD possessed an in vitro deconjugative activity on aminoluciferin-linked peptide and protein substrates in vitro A C73A mutation abolished SpvD activity, demonstrating that an intact catalytic triad is required for its function. Taken together, these results strongly suggest that SpvD is a cysteine protease. The amino acid sequence of SpvD is highly conserved across different S. enterica serovars, but residue 161, located close to the catalytic triad, is variable, with serovar Typhimurium SpvD having an arginine and serovar Enteritidis a glycine at this position. This variation affected hydrolytic activity of the enzyme on artificial substrates and can be explained by substrate accessibility to the active site. Interestingly, the SpvDG161 variant more potently inhibited NF-κB-mediated immune responses in cells in vitro and increased virulence of serovar Typhimurium in mice. In summary, our results explain the biochemical basis for the effect of virulence protein SpvD and demonstrate that a single amino acid polymorphism can affect the overall virulence of a bacterial pathogen in its host.
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Affiliation(s)
| | - Yue Zhang
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and
| | - Michal Przydacz
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and
| | | | - Yi Yang
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and
| | - Jonathan N Pruneda
- the Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge CB2 OQH, United Kingdom
| | - David Komander
- the Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge CB2 OQH, United Kingdom
| | | | - Stephen A Hare
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom and
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21
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Choby JE, Skaar EP. Heme Synthesis and Acquisition in Bacterial Pathogens. J Mol Biol 2016; 428:3408-28. [PMID: 27019298 PMCID: PMC5125930 DOI: 10.1016/j.jmb.2016.03.018] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 02/06/2023]
Abstract
Bacterial pathogens require the iron-containing cofactor heme to cause disease. Heme is essential to the function of hemoproteins, which are involved in energy generation by the electron transport chain, detoxification of host immune effectors, and other processes. During infection, bacterial pathogens must synthesize heme or acquire heme from the host; however, host heme is sequestered in high-affinity hemoproteins. Pathogens have evolved elaborate strategies to acquire heme from host sources, particularly hemoglobin, and both heme acquisition and synthesis are important for pathogenesis. Paradoxically, excess heme is toxic to bacteria and pathogens must rely on heme detoxification strategies. Heme is a key nutrient in the struggle for survival between host and pathogen, and its study has offered significant insight into the molecular mechanisms of bacterial pathogenesis.
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Affiliation(s)
- Jacob E Choby
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA; Tennessee Valley Healthcare System, U.S. Department of Veterans Affairs, Nashville, TN, USA.
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