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Lee M, Magante K, Gómez-Garzón C, Payne SM, Smith AT. Structural Determinants of Vibrio cholerae FeoB Nucleotide Promiscuity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.22.595361. [PMID: 38826458 PMCID: PMC11142208 DOI: 10.1101/2024.05.22.595361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Ferrous iron (Fe2+) is required for the growth and virulence of many pathogenic bacteria, including Vibrio cholerae (Vc), the causative agent of the disease cholera. For this bacterium, Feo is the primary system that transports Fe2+ into the cytosol. FeoB, the main component of this system, is regulated by a soluble cytosolic domain termed NFeoB. Recent reanalysis has shown that NFeoBs can be classified as either GTP-specific or NTP-promiscuous, but the structural and mechanistic bases for these differences were not known. To explore this intriguing property of FeoB, we solved the X-ray crystal structures of VcNFeoB in both the apo and GDP-bound forms. Surprisingly, this promiscuous NTPase displayed a canonical NFeoB G-protein fold like GTP-specific NFeoBs. Using structural bioinformatics, we hypothesized that residues surrounding the nucleobase could be important for both nucleotide affinity and specificity. We then solved the X-ray crystal structures of N150T VcNFeoB in the apo and GDP-bound forms to reveal H-bonding differences surround the guanine nucleobase. Interestingly, isothermal titration calorimetry revealed similar binding thermodynamics of the WT and N150T proteins to guanine nucleotides, while the behavior in the presence of adenine nucleotides was dramatically different. AlphaFold models of VcNFeoB in the presence of ADP and ATP showed important conformational changes that contribute to nucleotide specificity among FeoBs. Combined, these results provide a structural framework for understanding FeoB nucleotide promiscuity, which could be an adaptive measure utilized by pathogens to ensure adequate levels of intracellular iron across multiple metabolic landscapes.
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Affiliation(s)
- Mark Lee
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, 21250 USA
| | - Kate Magante
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, 21250 USA
| | - Camilo Gómez-Garzón
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712 USA
| | - Shelley M. Payne
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, 78712 USA
- John Ring LaMontagne Center for Infectious Disease, University of Texas at Austin, Austin, Texas, 78712 USA
| | - Aaron T. Smith
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, 21250 USA
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2
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Zhu L, Li W, Liu Y, Li J, Xu L, Gu L, Chen C, Cao Y, He Q. Metaproteomics analysis of anaerobic digestion of food waste by the addition of calcium peroxide and magnetite. Appl Environ Microbiol 2024; 90:e0145123. [PMID: 38224621 PMCID: PMC10880661 DOI: 10.1128/aem.01451-23] [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] [Received: 08/23/2023] [Accepted: 12/11/2023] [Indexed: 01/17/2024] Open
Abstract
Adding trace calcium peroxide and magnetite into a semi-continuous digester is a new method to effectively improve the anaerobic digestion of food waste. However, the microbial mechanism in this system has not been fully explored. Metaproteomics further revealed that the most active and significantly regulated genus u_p_Chloroflexi had formed a good cooperative relationship with Methanomicrobiales and Methanothrix in the system. u_p_Chloroflexi decomposed more organic compounds into CO2, acetate, amino acids, and other substances by alternating between short aerobic-anaerobic respiration. It perceived and adapted to the surrounding environment by producing biofilm, extracellular enzymes, and accelerating substrate transport, formed a respiratory barrier, and enhanced iron transport capacity by using highly expressed cytochrome C. The methanogens formed reactive oxygen species scavengers and reduced iron transport to prevent oxidative damage. This study provides new insight for improving the efficiency of anaerobic digestion of food waste and identifying key microorganisms and their regulated functional proteins in the calcium peroxide-magnetite digestion system.IMPORTANCEPrevious study has found that the combination of calcium peroxide and magnetite has a good promoting effect on the anaerobic digestion process of food waste. Through multiple omics approaches, information such as microbial population structure and changes in metabolites can be further analyzed. This study can help researchers gain a deeper understanding of the digestion pathway of food waste under the combined action of calcium peroxide and magnetite, further elucidate the impact mechanisms of calcium peroxide and magnetite at the microbial level, and provide theoretical guidance to improve the efficiency and stability of anaerobic digestion of food waste, as well as reduce operational costs. This research contributes to improving energy recovery efficiency, promoting sustainable management and development of food waste, and is of great significance to environmental protection.
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Affiliation(s)
- Lirong Zhu
- Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, China
| | - Wen Li
- Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, China
| | - Yongli Liu
- Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, China
| | - Jinze Li
- Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, China
| | - Linji Xu
- Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, China
| | - Li Gu
- Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, China
| | - Cong Chen
- Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, China
| | - Yang Cao
- Jiangsu Jiangnan Water Co., Ltd, Jiangyin, Jiangsu, China
| | - Qiang He
- Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, Chongqing, China
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Rychel K, Tan J, Patel A, Lamoureux C, Hefner Y, Szubin R, Johnsen J, Mohamed ETT, Phaneuf PV, Anand A, Olson CA, Park JH, Sastry AV, Yang L, Feist AM, Palsson BO. Laboratory evolution, transcriptomics, and modeling reveal mechanisms of paraquat tolerance. Cell Rep 2023; 42:113105. [PMID: 37713311 PMCID: PMC10591938 DOI: 10.1016/j.celrep.2023.113105] [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: 02/09/2023] [Revised: 07/09/2023] [Accepted: 08/23/2023] [Indexed: 09/17/2023] Open
Abstract
Relationships between the genome, transcriptome, and metabolome underlie all evolved phenotypes. However, it has proved difficult to elucidate these relationships because of the high number of variables measured. A recently developed data analytic method for characterizing the transcriptome can simplify interpretation by grouping genes into independently modulated sets (iModulons). Here, we demonstrate how iModulons reveal deep understanding of the effects of causal mutations and metabolic rewiring. We use adaptive laboratory evolution to generate E. coli strains that tolerate high levels of the redox cycling compound paraquat, which produces reactive oxygen species (ROS). We combine resequencing, iModulons, and metabolic models to elucidate six interacting stress-tolerance mechanisms: (1) modification of transport, (2) activation of ROS stress responses, (3) use of ROS-sensitive iron regulation, (4) motility, (5) broad transcriptional reallocation toward growth, and (6) metabolic rewiring to decrease NADH production. This work thus demonstrates the power of iModulon knowledge mapping for evolution analysis.
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Affiliation(s)
- Kevin Rychel
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Justin Tan
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Arjun Patel
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Cameron Lamoureux
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ying Hefner
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Richard Szubin
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Josefin Johnsen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Elsayed Tharwat Tolba Mohamed
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Patrick V Phaneuf
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Amitesh Anand
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, Maharashtra, India
| | - Connor A Olson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Joon Ho Park
- Department of Chemical Engineering, Massachusetts Institute of Technology, 500 Main Street, Building 76, Cambridge, MA 02139, USA
| | - Anand V Sastry
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Laurence Yang
- Department of Chemical Engineering, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Adam M Feist
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA; Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA; Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark.
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Van V, Brown JB, O'Shea CR, Rosenbach H, Mohamed I, Ejimogu NE, Bui TS, Szalai VA, Chacón KN, Span I, Zhang F, Smith AT. Iron-sulfur clusters are involved in post-translational arginylation. Nat Commun 2023; 14:458. [PMID: 36709327 PMCID: PMC9884297 DOI: 10.1038/s41467-023-36158-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 01/18/2023] [Indexed: 01/30/2023] Open
Abstract
Eukaryotic arginylation is an essential post-translational modification that modulates protein stability and regulates protein half-life. Arginylation is catalyzed by a family of enzymes known as the arginyl-tRNA transferases (ATE1s), which are conserved across the eukaryotic domain. Despite their conservation and importance, little is known regarding the structure, mechanism, and regulation of ATE1s. In this work, we show that ATE1s bind a previously undiscovered [Fe-S] cluster that is conserved across evolution. We characterize the nature of this [Fe-S] cluster and find that the presence of the [Fe-S] cluster in ATE1 is linked to its arginylation activity, both in vitro and in vivo, and the initiation of the yeast stress response. Importantly, the ATE1 [Fe-S] cluster is oxygen-sensitive, which could be a molecular mechanism of the N-degron pathway to sense oxidative stress. Taken together, our data provide the framework of a cluster-based paradigm of ATE1 regulatory control.
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Affiliation(s)
- Verna Van
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Janae B Brown
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Corin R O'Shea
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - Hannah Rosenbach
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Ijaz Mohamed
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Nna-Emeka Ejimogu
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Toan S Bui
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Veronika A Szalai
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Kelly N Chacón
- Department of Chemistry, Reed College, Portland, OR, 97202, USA
| | - Ingrid Span
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany
| | - Fangliang Zhang
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA.,Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Aaron T Smith
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA.
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5
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Van V, Smith AT. Reconstitution of the Arginyltransferase (ATE1) Iron-Sulfur Cluster. Methods Mol Biol 2023; 2620:209-217. [PMID: 37010764 DOI: 10.1007/978-1-0716-2942-0_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
Abstract
As global regulators of eukaryotic homeostasis, arginyltransferases (ATE1s) have essential functions within the cell. Thus, the regulation of ATE1 is paramount. It was previously postulated that ATE1 was a hemoprotein and that heme was an operative cofactor responsible for enzymatic regulation and inactivation. However, we have recently shown that ATE1 instead binds an iron-sulfur ([Fe-S]) cluster that appears to function as an oxygen sensor to regulate ATE1 activity. As this cofactor is oxygen-sensitive, purification of ATE1 in the presence of O2 results in cluster decomposition and loss. Here, we describe an anoxic chemical reconstitution protocol to assemble the [Fe-S] cluster cofactor in Saccharomyces cerevisiae ATE1 (ScATE1) and Mus musculus ATE1 isoform 1 (MmATE1-1).
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Affiliation(s)
- Verna Van
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, USA
| | - Aaron T Smith
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, USA.
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6
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Transcriptome analysis reveals reasons for the low tolerance of Clostridium tyrobutyricum to furan derivatives. Appl Microbiol Biotechnol 2022; 107:327-339. [DOI: 10.1007/s00253-022-12281-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 10/30/2022] [Accepted: 11/04/2022] [Indexed: 11/25/2022]
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7
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Sestok AE, O'Sullivan SM, Smith AT. A general protocol for the expression and purification of the intact transmembrane transporter FeoB. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183973. [PMID: 35636558 PMCID: PMC9203943 DOI: 10.1016/j.bbamem.2022.183973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 04/27/2023]
Abstract
Ferrous iron (Fe2+) transport is an essential process that supports the growth, intracellular survival, and virulence of several drug-resistant pathogens, and the ferrous iron transport (Feo) system is the most important and widespread protein complex that mediates Fe2+ transport in these organisms. The Feo system canonically comprises three proteins (FeoA/B/C). FeoA and FeoC are both small, accessory proteins localized to the cytoplasm, and their roles in the Fe2+ transport process have been of great debate. FeoB is the only wholly-conserved component of the Feo system and serves as the inner membrane-embedded Fe2+ transporter with a soluble G-protein-like N-terminal domain. In vivo studies have underscored the importance of Feo during infection, emphasizing the need to better understand Feo-mediated Fe2+ uptake, although a paucity of research exists on intact FeoB. To surmount this problem, we designed an overproduction and purification system that can be applied generally to a suite of intact FeoBs from several organisms. Importantly, we noted that FeoB is extremely sensitive to excess salt while in the membrane of a recombinant host, and we designed a workflow to circumvent this issue. We also demonstrated effective protein extraction from the lipid bilayer through small-scale solubilization studies. We then applied this approach to the large-scale purifications of Escherichia coli and Pseudomonas aeruginosa FeoBs to high purity and homogeneity. Lastly, we show that our protocol can be generally applied to various FeoB proteins. Thus, this workflow allows for isolation of suitable quantities of FeoB for future biochemical and biophysical characterization.
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Affiliation(s)
- Alex E Sestok
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Sean M O'Sullivan
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Aaron T Smith
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA.
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8
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Brown JB, Lee MA, Smith AT. The structure of Vibrio cholerae FeoC reveals conservation of the helix-turn-helix motif but not the cluster-binding domain. J Biol Inorg Chem 2022; 27:485-495. [PMID: 35796835 PMCID: PMC9398973 DOI: 10.1007/s00775-022-01945-4] [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: 02/28/2022] [Accepted: 06/04/2022] [Indexed: 11/26/2022]
Abstract
Most pathogenic bacteria require ferrous iron (Fe2+) in order to sustain infection within hosts. The ferrous iron transport (Feo) system is the most highly conserved prokaryotic transporter of Fe2+, but its mechanism remains to be fully characterized. Most Feo systems are composed of two proteins: FeoA, a soluble SH3-like accessory protein, and FeoB, a membrane protein that translocates Fe2+ across a lipid bilayer. Some bacterial feo operons encode FeoC, a third soluble, winged-helix protein that remains enigmatic in function. We previously demonstrated that selected FeoC proteins bind O2-sensitive [4Fe-4S] clusters via Cys residues, leading to the proposal that some FeoCs could sense O2 to regulate Fe2+ transport. However, not all FeoCs conserve these Cys residues, and FeoC from the causative agent of cholera (Vibrio cholerae) notably lacks any Cys residues, precluding cluster binding. In this work, we determined the NMR structure of VcFeoC, which is monomeric and conserves the helix-turn-helix domain seen in other FeoCs. In contrast, however, the structure of VcFeoC reveals a truncated winged β-sheet in which the cluster-binding domain is notably absent. Using homology modeling, we predicted the structure of VcNFeoB and used docking to identify an interaction site with VcFeoC, which is confirmed by NMR spectroscopy. These findings provide the first atomic-level structure of VcFeoC and contribute to a better understanding of its role vis-à-vis FeoB.
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Affiliation(s)
- Janae B Brown
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Mark A Lee
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA
| | - Aaron T Smith
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD, 21250, USA.
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9
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Abstract
Iron acquisition is essential for almost all living organisms. In certain environments, ferrous iron is the most prevalent form of this element. Feo is the most widespread system for ferrous iron uptake in bacteria and is critical for virulence in some species. The canonical architecture of Feo consists of a large transmembrane nucleoside triphosphatase (NTPase) protein, FeoB, and two accessory cytoplasmic proteins, FeoA and FeoC. The role of the latter components and the mechanism by which Feo orchestrates iron transport are unclear. In this study, we conducted a comparative analysis of Feo protein sequences to gain insight into the evolutionary history of this transporter. We identified instances of how horizontal gene transfer contributed to the evolution of Feo. Also, we found that FeoC, while absent in most lineages, is largely present in the Gammaproteobacteria group, although its sequence is poorly conserved. We propose that FeoC, which may couple FeoB NTPase activity with pore opening, was an ancestral element that has been dispensed with through mutations in FeoA and FeoB in some lineages. We provide experimental evidence supporting this hypothesis by isolating and characterizing FeoC-independent mutants of the Vibrio cholerae Feo system. Also, we confirmed that the closely related species Shewanella oneidensis does not require FeoC; thus, Vibrio FeoC sequences may resemble transitional forms on an evolutionary pathway toward FeoC-independent transporters. Finally, by combining data from our bioinformatic analyses with this experimental evidence, we propose an evolutionary model for the Feo system in bacteria. IMPORTANCE Feo, a ferrous iron transport system composed of three proteins (FeoA, -B, and -C), is the most prevalent bacterial iron transporter. It plays an important role in iron acquisition in low-oxygen environments and some host-pathogen interactions. The large transmembrane protein FeoB provides the channel for the transport of iron into the bacterial cell, but the functions of the two small, required accessory proteins FeoA and FeoC are not well understood. Analysis of the evolution of this transporter shows that FeoC is poorly conserved and has been lost from many bacterial lineages. Experimental evidence indicates that FeoC may have different functions in different species that retain this protein, and the loss of FeoC is promoted by mutations in FeoA or by the fusion of FeoA and FeoB.
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Brown JB, Lee MA, Smith AT. Ins and Outs: Recent Advancements in Membrane Protein-Mediated Prokaryotic Ferrous Iron Transport. Biochemistry 2021; 60:3277-3291. [PMID: 34670078 DOI: 10.1021/acs.biochem.1c00586] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Iron is an essential nutrient for virtually every living organism, especially pathogenic prokaryotes. Despite its importance, however, both the acquisition and the export of this element require dedicated pathways that are dependent on oxidation state. Due to its solubility and kinetic lability, reduced ferrous iron (Fe2+) is useful to bacteria for import, chaperoning, and efflux. Once imported, ferrous iron may be loaded into apo and nascent enzymes and even sequestered into storage proteins under certain conditions. However, excess labile ferrous iron can impart toxicity as it may spuriously catalyze Fenton chemistry, thereby generating reactive oxygen species and leading to cellular damage. In response, it is becoming increasingly evident that bacteria have evolved Fe2+ efflux pumps to deal with conditions of ferrous iron excess and to prevent intracellular oxidative stress. In this work, we highlight recent structural and mechanistic advancements in our understanding of prokaryotic ferrous iron import and export systems, with a focus on the connection of these essential transport systems to pathogenesis. Given the connection of these pathways to the virulence of many increasingly antibiotic resistant bacterial strains, a greater understanding of the mechanistic details of ferrous iron cycling in pathogens could illuminate new pathways for future therapeutic developments.
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Affiliation(s)
- Janae B Brown
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
| | - Mark A Lee
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
| | - Aaron T Smith
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
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11
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Cain TJ, Smith AT. Ferric iron reductases and their contribution to unicellular ferrous iron uptake. J Inorg Biochem 2021; 218:111407. [PMID: 33684686 PMCID: PMC8035299 DOI: 10.1016/j.jinorgbio.2021.111407] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 01/29/2021] [Accepted: 02/19/2021] [Indexed: 12/21/2022]
Abstract
Iron is a necessary element for nearly all forms of life, and the ability to acquire this trace nutrient has been identified as a key virulence factor for the establishment of infection by unicellular pathogens. In the presence of O2, iron typically exists in the ferric (Fe3+) oxidation state, which is highly unstable in aqueous conditions, necessitating its sequestration into cofactors and/or host proteins to remain soluble. To counter this insolubility, and to compete with host sequestration mechanisms, many unicellular pathogens will secrete low molecular weight, high-affinity Fe3+ chelators known as siderophores. Once acquired, unicellular pathogens must liberate the siderophore-bound Fe3+ in order to assimilate this nutrient into metabolic pathways. While these organisms may hydrolyze the siderophore backbone to release the chelated Fe3+, this approach is energetically costly. Instead, iron may be liberated from the Fe3+-siderophore complex through reduction to Fe2+, which produces a lower-affinity form of iron that is highly soluble. This reduction is performed by a class of enzymes known as ferric reductases. Ferric reductases are broadly-distributed electron-transport proteins that are expressed by numerous infectious organisms and are connected to the virulence of unicellular pathogens. Despite this importance, ferric reductases remain poorly understood. This review provides an overview of our current understanding of unicellular ferric reductases (both soluble and membrane-bound), with an emphasis on the important but underappreciated connection between ferric-reductase mediated Fe3+ reduction and the transport of Fe2+ via ferrous iron transporters.
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Affiliation(s)
- Timothy J Cain
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Aaron T Smith
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA.
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12
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Zhang Y, Sen S, Giedroc DP. Iron Acquisition by Bacterial Pathogens: Beyond Tris-Catecholate Complexes. Chembiochem 2020; 21:1955-1967. [PMID: 32180318 PMCID: PMC7367709 DOI: 10.1002/cbic.201900778] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/06/2020] [Indexed: 12/11/2022]
Abstract
Sequestration of the essential nutrient iron from bacterial invaders that colonize the vertebrate host is a central feature of nutritional immunity and the "fight over transition metals" at the host-pathogen interface. The iron quota for many bacterial pathogens is large, as iron enzymes often make up a significant share of the metalloproteome. Iron enzymes play critical roles in respiration, energy metabolism, and other cellular processes by catalyzing a wide range of oxidation-reduction, electron transfer, and oxygen activation reactions. In this Concept article, we discuss recent insights into the diverse ways that bacterial pathogens acquire this essential nutrient, beyond the well-characterized tris-catecholate FeIII complexes, in competition and cooperation with significant host efforts to cripple these processes. We also discuss pathogen strategies to adapt their metabolism to less-than-optimal iron concentrations, and briefly speculate on what might be an integrated adaptive response to the concurrent limitation of both iron and zinc in the infected host.
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Affiliation(s)
- Yifan Zhang
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405-7102, USA
| | - Sambuddha Sen
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, USA
| | - David P Giedroc
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405-7102, USA
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13
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Gómez-Garzón C, Payne SM. Vibrio cholerae FeoB hydrolyzes ATP and GTP in vitro in the absence of stimulatory factors. Metallomics 2020; 12:2065-2074. [PMID: 33174898 DOI: 10.1039/d0mt00195c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Feo is the most widely conserved system for ferrous iron transport in prokaryotes, and it is important for virulence in some pathogens. However, its mechanism of iron transport is not fully understood. In this study, we used full-length Vibrio cholerae FeoB (VcFeoB) as a model system to study whether its enzymatic activity is affected by regulatory factors commonly associated with FeoB proteins from other species or with G-proteins that have homology to FeoB. VcFeoB showed a higher rate of hydrolysis of both ATP and GTP than its N-terminal domain alone; likewise, ions such as K+ and Fe2+ did not modulate its nucleotide hydrolysis. We also showed that the three V. cholerae Feo proteins (FeoA, FeoB, and FeoC) work in a 1 : 1 : 1 molar ratio in vivo. Although both FeoA and FeoC are required for Feo-mediated iron transport, neither of these proteins affected the VcFeoB NTPase rate. These results are consistent with an active transport mechanism independent of stimulatory factors and highlight the importance of using full-length FeoB proteins as a reliable proxy to study Feo-mediated iron transport in vitro.
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Affiliation(s)
- Camilo Gómez-Garzón
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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