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Jakob S, Steinchen W, Hanßmann J, Rosum J, Langenfeld K, Osorio-Valeriano M, Steube N, Giammarinaro PI, Hochberg GKA, Glatter T, Bange G, Diepold A, Thanbichler M. The virulence regulator VirB from Shigella flexneri uses a CTP-dependent switch mechanism to activate gene expression. Nat Commun 2024; 15:318. [PMID: 38182620 PMCID: PMC10770331 DOI: 10.1038/s41467-023-44509-z] [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] [Received: 06/02/2023] [Accepted: 12/11/2023] [Indexed: 01/07/2024] Open
Abstract
The transcriptional antisilencer VirB acts as a master regulator of virulence gene expression in the human pathogen Shigella flexneri. It binds DNA sequences (virS) upstream of VirB-dependent promoters and counteracts their silencing by the nucleoid-organizing protein H-NS. However, its precise mode of action remains unclear. Notably, VirB is not a classical transcription factor but related to ParB-type DNA-partitioning proteins, which have recently been recognized as DNA-sliding clamps using CTP binding and hydrolysis to control their DNA entry gate. Here, we show that VirB binds CTP, embraces DNA in a clamp-like fashion upon its CTP-dependent loading at virS sites and slides laterally on DNA after clamp closure. Mutations that prevent CTP-binding block VirB loading in vitro and abolish the formation of VirB nucleoprotein complexes as well as virulence gene expression in vivo. Thus, VirB represents a CTP-dependent molecular switch that uses a loading-and-sliding mechanism to control transcription during bacterial pathogenesis.
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Affiliation(s)
- Sara Jakob
- Department of Biology, University of Marburg, Marburg, Germany
| | - Wieland Steinchen
- Department of Chemistry, University of Marburg, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Juri Hanßmann
- Department of Biology, University of Marburg, Marburg, Germany
- Max Planck Fellow Group Bacterial Cell Biology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Julia Rosum
- Department of Biology, University of Marburg, Marburg, Germany
| | - Katja Langenfeld
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Manuel Osorio-Valeriano
- Department of Biology, University of Marburg, Marburg, Germany
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Niklas Steube
- Evolutionary Biochemistry Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Pietro I Giammarinaro
- Department of Chemistry, University of Marburg, Marburg, Germany
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Georg K A Hochberg
- Department of Chemistry, University of Marburg, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
- Evolutionary Biochemistry Group, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Timo Glatter
- Mass Spectrometry and Proteomics Facility, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Gert Bange
- Department of Chemistry, University of Marburg, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
- Max Planck Fellow Group Molecular Physiology of Microbes, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Andreas Diepold
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Martin Thanbichler
- Department of Biology, University of Marburg, Marburg, Germany.
- Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany.
- Max Planck Fellow Group Bacterial Cell Biology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
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2
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Du J, Zhang C, Long Q, Zhang L, Chen W, Liu Q. Characterization of a pathway-specific activator of edeine biosynthesis and improved edeine production by its overexpression in Brevibacillus brevis. FRONTIERS IN PLANT SCIENCE 2022; 13:1022476. [PMID: 36388555 PMCID: PMC9641203 DOI: 10.3389/fpls.2022.1022476] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 09/27/2022] [Indexed: 06/16/2023]
Abstract
Edeines are a group of non-ribosomal antibacterial peptides produced by Brevibacillus brevis. Due to the significant antibacterial properties of edeines, increasing edeine yield is of great interest in biomedical research. Herein, we identified that EdeB, a member of the ParB protein family, significantly improved edeine production in B. brevis. First, overexpression of edeB in B. brevis X23 increased edeine production by 92.27%. Second, in vitro bacteriostasis experiment showed that edeB-deletion mutant exhibited less antibacterial activity. Third, RT-qPCR assay demonstrated that the expression of edeA, edeQ, and edeK, which are key components of the edeine biosynthesis pathway, in edeB-deletion mutant X23(ΔedeB) was significantly lower than that in wild-type B. brevis strain X23. Finally, electrophoretic mobility shift assay (EMSA) showed that EdeB directly bound to the promoter region of the edeine biosynthetic gene cluster (ede BGC), suggesting that EdeB improves edeine production through interaction with ede BGC in B. brevis.
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Affiliation(s)
- Jie Du
- Hunan Provincial Engineering and Technology Research Center for Agricultural Microbiology Application, Hunan Institute of Microbiology, Changsha, China
| | - Cuiyang Zhang
- Hunan Provincial Engineering and Technology Research Center for Agricultural Microbiology Application, Hunan Institute of Microbiology, Changsha, China
| | - Qingshan Long
- Hunan Provincial Engineering and Technology Research Center for Agricultural Microbiology Application, Hunan Institute of Microbiology, Changsha, China
| | - Liang Zhang
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Wu Chen
- College of Plant Protection, Hunan Agricultural University, Changsha, China
| | - Qingshu Liu
- Hunan Provincial Engineering and Technology Research Center for Agricultural Microbiology Application, Hunan Institute of Microbiology, Changsha, China
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3
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The Key Element Role of Metallophores in the Pathogenicity and Virulence of Staphylococcus aureus: A Review. BIOLOGY 2022; 11:biology11101525. [PMID: 36290427 PMCID: PMC9598555 DOI: 10.3390/biology11101525] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/17/2022] [Accepted: 10/14/2022] [Indexed: 11/05/2022]
Abstract
The ubiquitous bacterium Staphylococcus aureus causes many diseases that sometimes can be fatal due to its high pathogenicity. The latter is caused by the ability of this pathogen to secrete secondary metabolites, enabling it to colonize inside the host causing infection through various processes. Metallophores are secondary metabolites that enable bacteria to sequester metal ions from the surrounding environment since the availability of metal ions is crucial for bacterial metabolism and virulence. The uptake of iron and other metal ions such as nickel and zinc is one of these essential mechanisms that gives this germ its virulence properties and allow it to overcome the host immune system. Additionally, extensive interactions occur between this pathogen and other bacteria as they compete for resources. Staphylococcus aureus has high-affinity metal import pathways including metal ions acquisition, recruitment and metal-chelate complex import. These characteristics give this bacterium the ability to intake metallophores synthesized by other bacteria, thus enabling it to compete with other microorganisms for the limited nutrients. In scarce host conditions, free metal ions are extremely low because they are confined to storage and metabolic molecules, so metal ions are sequestered by metallophores produced by this bacterium. Both siderophores (iron chelating molecules) and staphylopine (wide- spectrum metallophore) are secreted by Staphylococcus aureus giving it infectious properties. The genetic regulation of the synthesis and export together with the import of metal loaded metallophores are well established and are all covered in this review.
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Identification and Enzymatic Analysis of an Archaeal ATP-Dependent Serine Kinase from the Hyperthermophilic Archaeon Staphylothermus marinus. J Bacteriol 2021; 203:e0002521. [PMID: 34096778 DOI: 10.1128/jb.00025-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Serine kinase catalyzes the phosphorylation of free serine (Ser) to produce O-phosphoserine (Sep). An ADP-dependent Ser kinase in the hyperthermophilic archaeon Thermococcus kodakarensis (Tk-SerK) is involved in cysteine (Cys) biosynthesis and most likely Ser assimilation. An ATP-dependent Ser kinase in the mesophilic bacterium Staphylococcus aureus is involved in siderophore biosynthesis. Although proteins displaying various degrees of similarity with Tk-SerK are distributed in a wide range of organisms, it is unclear if they are actually Ser kinases. Here, we examined proteins from Desulfurococcales species in Crenarchaeota that display moderate similarity with Tk-SerK from Euryarchaeota (42 to 45% identical). Tk-serK homologs from Staphylothermus marinus (Smar_0555), Desulfurococcus amylolyticus (DKAM_0858), and Desulfurococcus mucosus (Desmu_0904) were expressed in Escherichia coli. All three partially purified recombinant proteins exhibited Ser kinase activity utilizing ATP rather than ADP as a phosphate donor. Purified Smar_0555 protein displayed activity for l-Ser but not other compounds, including d-Ser, l-threonine, and l-homoserine. The enzyme utilized ATP, UTP, GTP, CTP, and the inorganic polyphosphates triphosphate and tetraphosphate as phosphate donors. Kinetic analysis indicated that the Smar_0555 protein preferred nucleoside 5'-triphosphates over triphosphate as a phosphate donor. Transcript levels and Ser kinase activity in S. marinus cells grown with or without serine suggested that the Smar_0555 gene is constitutively expressed. The genes encoding Ser kinases examined here form an operon with genes most likely responsible for the conversion between Sep and 3-phosphoglycerate of central sugar metabolism, suggesting that the ATP-dependent Ser kinases from Desulfurococcales play a role in the assimilation of Ser. IMPORTANCE Homologs of the ADP-dependent Ser kinase from the archaeon Thermococcus kodakarensis (Tk-SerK) include representatives from all three domains of life. The results of this study show that even homologs from the archaeal order Desulfurococcales, which are the most structurally related to the ADP-dependent Ser kinases from the Thermococcales, are Ser kinases that utilize ATP, and in at least some cases inorganic polyphosphates, as the phosphate donor. The differences in properties between the Desulfurococcales and Thermococcales enzymes raise the possibility that Tk-SerK homologs constitute a group of kinases that phosphorylate free serine with a wide range of phosphate donors.
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Wohlgemuth R. Key advances in biocatalytic phosphorylations in the last two decades: Biocatalytic syntheses in vitro and biotransformations in vivo (in humans). Biotechnol J 2020; 16:e2000090. [PMID: 33283467 DOI: 10.1002/biot.202000090] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/06/2020] [Indexed: 01/05/2023]
Abstract
Biocatalytic phosphorylation reactions provide several benefits, such as more direct, milder, more selective, and shorter access routes to phosphorylated products. Favorable characteristics of biocatalytic methodologies represent advantages for in vitro as well as for in vivo phosphorylation reactions, leading to important advances in the science of synthesis towards bioactive phosphorylated compounds in various areas. The scope of this review covers key advances of biocatalytic phosphorylation reactions over the last two decades, for biocatalytic syntheses in vitro and for biotransformations in vivo (in humans). From the origins of probiotic life to in vitro synthetic applications and in vivo formation of bioactive pharmaceuticals, the common purpose is to outline the importance, relevance, and underlying connections of biocatalytic phosphorylations of small molecules. Asymmetric phosphorylations attracting increased attention are highlighted. Phosphohydrolases, phosphotransferases, phosphorylases, phosphomutases, and other enzymes involved in phosphorus chemistry provide powerful toolboxes for resource-efficient and selective in vitro biocatalytic syntheses of phosphorylated metabolites, chiral building blocks, pharmaceuticals as well as in vivo enzymatic formation of biologically active forms of pharmaceuticals. Nature's large diversity of phosphoryl-group-transferring enzymes, advanced enzyme and reaction engineering toolboxes make biocatalytic asymmetric phosphorylations using enzymes a powerful and privileged phosphorylation methodology.
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Affiliation(s)
- Roland Wohlgemuth
- Institute of Molecular and Industrial Biotechnology, Lodz University of Technology, Lodz, Poland.,Swiss Coordination Committee Biotechnology, Zurich, Switzerland
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6
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Hsu SH, Zhang S, Huang SC, Wu TK, Xu Z, Chang CY. Characterization of Enzymes Catalyzing the Formation of the Nonproteinogenic Amino Acid l-Dap in Capreomycin Biosynthesis. Biochemistry 2020; 60:77-84. [PMID: 33356147 DOI: 10.1021/acs.biochem.0c00808] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Capreomycin (CMN) and viomycin (VIO) are nonribosomal peptide antituberculosis antibiotics, the structures of which contain four nonproteinogenic amino acids, including l-2,3-diaminopropionic acid (l-Dap), β-ureidodehydroalanine, l-capreomycidine, and β-lysine. Previous bioinformatics analysis suggested that CmnB/VioB and CmnK/VioK participate in the formation of l-Dap; however, the real substrates of these enzymes are yet to be confirmed. We herein show that starting from O-phospho-l-Ser (OPS) and l-Glu precursors, CmnB catalyzes the condensation reaction to generate a metabolite intermediate N-(1-amino-1-carboxyl-2-ethyl)glutamic acid (ACEGA), which undergoes NAD+-dependent oxidative hydrolysis by CmnK to generate l-Dap. Furthermore, the binding site of ACEGA and the catalytic mechanism of CmnK were elucidated with the assistance of three crystal structures, including those of apo-CmnK, the NAD+-CmnK complex, and CmnK in an alternative conformation. The CmnK-ACEGA docking model revealed that the glutamate α-hydrogen points toward the nicotinamide moiety. It provides evidence that the reaction is dependent on hydride transfer to form an imine intermediate, which is subsequently hydrolyzed by a water molecule to produce l-Dap. These findings modify the original proposed pathway and provide insights into l-Dap formation in the biosynthesis of other related natural products.
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Affiliation(s)
- Sheng-Hsin Hsu
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC
| | - Shouqi Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Sheng-Cih Huang
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC
| | - Tung-Kung Wu
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC
| | - Zhengren Xu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Chin-Yuan Chang
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC.,Center for Intelligent Drug Systems and Smart Bio-devices, National Chiao Tung University, Hsinchu 30010, Taiwan, ROC
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7
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Marchetti M, De Bei O, Bettati S, Campanini B, Kovachka S, Gianquinto E, Spyrakis F, Ronda L. Iron Metabolism at the Interface between Host and Pathogen: From Nutritional Immunity to Antibacterial Development. Int J Mol Sci 2020; 21:E2145. [PMID: 32245010 PMCID: PMC7139808 DOI: 10.3390/ijms21062145] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 02/08/2023] Open
Abstract
Nutritional immunity is a form of innate immunity widespread in both vertebrates and invertebrates. The term refers to a rich repertoire of mechanisms set up by the host to inhibit bacterial proliferation by sequestering trace minerals (mainly iron, but also zinc and manganese). This strategy, selected by evolution, represents an effective front-line defense against pathogens and has thus inspired the exploitation of iron restriction in the development of innovative antimicrobials or enhancers of antimicrobial therapy. This review focuses on the mechanisms of nutritional immunity, the strategies adopted by opportunistic human pathogen Staphylococcus aureus to circumvent it, and the impact of deletion mutants on the fitness, infectivity, and persistence inside the host. This information finally converges in an overview of the current development of inhibitors targeting the different stages of iron uptake, an as-yet unexploited target in the field of antistaphylococcal drug discovery.
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Affiliation(s)
- Marialaura Marchetti
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
| | - Omar De Bei
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (O.D.B.); (B.C.)
| | - Stefano Bettati
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy
- Institute of Biophysics, National Research Council, 56124 Pisa, Italy
- National Institute of Biostructures and Biosystems, 00136 Rome, Italy
| | - Barbara Campanini
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (O.D.B.); (B.C.)
| | - Sandra Kovachka
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Eleonora Gianquinto
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Francesca Spyrakis
- Department of Drug Science and Technology, University of Turin, 10125 Turin, Italy; (S.K.); (E.G.); (F.S.)
| | - Luca Ronda
- Interdepartmental Center Biopharmanet-TEC, University of Parma, 43124 Parma, Italy; (M.M.); (S.B.)
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy
- Institute of Biophysics, National Research Council, 56124 Pisa, Italy
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Abstract
Natural nonproteinogenic amino acids vastly outnumber the well-known 22 proteinogenic amino acids. Such amino acids are generated in specialized metabolic pathways. In these pathways, diverse biosynthetic transformations, ranging from isomerizations to the stereospecific functionalization of C-H bonds, are employed to generate structural diversity. The resulting nonproteinogenic amino acids can be integrated into more complex natural products. Here we review recently discovered biosynthetic routes to freestanding nonproteinogenic α-amino acids, with an emphasis on work reported between 2013 and mid-2019.
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Affiliation(s)
- Jason B Hedges
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Katherine S Ryan
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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9
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Verstraete MM, Morales LD, Kobylarz MJ, Loutet SA, Laakso HA, Pinter TB, Stillman MJ, Heinrichs DE, Murphy MEP. The heme-sensitive regulator SbnI has a bifunctional role in staphyloferrin B production by Staphylococcus aureus. J Biol Chem 2019; 294:11622-11636. [PMID: 31197035 DOI: 10.1074/jbc.ra119.007757] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 06/12/2019] [Indexed: 01/30/2023] Open
Abstract
Staphylococcus aureus infection relies on iron acquisition from its host. S. aureus takes up iron through heme uptake by the iron-responsive surface determinant (Isd) system and by the production of iron-scavenging siderophores. Staphyloferrin B (SB) is a siderophore produced by the 9-gene sbn gene cluster for SB biosynthesis and efflux. Recently, the ninth gene product, SbnI, was determined to be a free l-serine kinase that produces O-phospho-l-serine (OPS), a substrate for SB biosynthesis. Previous studies have also characterized SbnI as a DNA-binding regulatory protein that senses heme to control sbn gene expression for SB synthesis. Here, we present crystal structures at 1.9-2.1 Å resolution of a SbnI homolog from Staphylococcus pseudintermedius (SpSbnI) in both apo form and in complex with ADP, a product of the kinase reaction; the latter confirmed the active-site location. The structures revealed that SpSbnI forms a dimer through C-terminal domain swapping and a dimer of dimers through intermolecular disulfide formation. Heme binding had only a modest effect on SbnI enzymatic activity, suggesting that its two functions are independent and structurally distinct. We identified a heme-binding site and observed catalytic heme transfer between a heme-degrading protein of the Isd system, IsdI, and SbnI. These findings support the notion that SbnI has a bifunctional role contributing precursor OPS to SB synthesis and directly sensing heme to control expression of the sbn locus. We propose that heme transfer from IsdI to SbnI enables S. aureus to control iron source preference according to the sources available in the environment.
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Affiliation(s)
- Meghan M Verstraete
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - L Daniela Morales
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Marek J Kobylarz
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Slade A Loutet
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Holly A Laakso
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Tyler B Pinter
- Department of Chemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Martin J Stillman
- Department of Chemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - David E Heinrichs
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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10
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Conroy BS, Grigg JC, Kolesnikov M, Morales LD, Murphy MEP. Staphylococcus aureus heme and siderophore-iron acquisition pathways. Biometals 2019; 32:409-424. [PMID: 30911924 DOI: 10.1007/s10534-019-00188-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 03/18/2019] [Indexed: 11/24/2022]
Abstract
Staphylococcus aureus is a versatile opportunistic human pathogen. Infection by this bacterium requires uptake of iron from the human host, but iron is highly restricted in this environment. Staphylococcus aureus iron sufficiency is achieved primarily through uptake of heme and high-affinity iron chelators, known as siderophores. Two siderophores (staphyloferrins) are produced and secreted by S. aureus into the extracellular environment to capture iron. Staphylococcus aureus expresses specific uptake systems for staphyloferrins and more general uptake systems for siderophores produced by other microorganisms. The S. aureus heme uptake system uses highly-specific cell surface receptors to extract heme from hemoglobin and hemoglobin-haptoglobin complexes for transport into the cytoplasm where it is degraded to liberate iron. Initially thought to be independent systems, recent findings indicate that these iron uptake pathways intersect. IruO is a reductase that releases iron from heme and some ferric-siderophores. Moreover, multifunctional SbnI produces a precursor for staphyloferrin B biosynthesis, and also binds heme to regulate expression of the staphyloferrin B biosynthesis pathway. Intersection of the S. aureus iron uptake pathways is hypothesized to be important for rapid adaptation to available iron sources. Components of the heme and siderophore uptake systems are currently being targeted in the development of therapeutics against S. aureus.
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Affiliation(s)
- Brigid S Conroy
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Jason C Grigg
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Maxim Kolesnikov
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - L Daniela Morales
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada.
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