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Gonococcal Clinical Strains Bearing a Common gdhR Single Nucleotide Polymorphism That Results in Enhanced Expression of the Virulence Gene lctP Frequently Possess a mtrR Promoter Mutation That Decreases Antibiotic Susceptibility. mBio 2022; 13:e0027622. [PMID: 35258329 PMCID: PMC9040798 DOI: 10.1128/mbio.00276-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
GdhR is a transcriptional repressor of the virulence factor gene lctP, which encodes a unique l-lactate permease that has been linked to pathogenesis of Neisseria gonorrhoeae, and loss of gdhR can confer increased fitness of gonococci in a female mouse model of lower genital tract infection. In this work, we identified a single nucleotide polymorphism (SNP) in gdhR, which is often present in both recent and historical gonococcal clinical strains and results in a proline (P)-to-serine (S) change at amino acid position 6 (P6S) of GdhR. This mutation (gdhR6) was found to reduce GdhR transcriptional repression at lctP in gonococcal strains containing the mutant protein compared to wild-type GdhR. By using purified recombinant proteins and in vitro DNA-binding and cross-linking experiments, we found that gdhR6 impairs the DNA-binding activity of GdhR at lctP without an apparent effect on protein oligomerization. By analyzing a panel of U.S. (from 2017 to 2018) and Danish (1928 to 2013) clinical isolates, we observed a statistical association between gdhR6 and the previously described adenine deletion in the promoter of mtrR (mtrR-P A-del), encoding the repressor (MtrR) of the mtrCDE operon that encodes the MtrCDE multidrug efflux pump that can export antibiotics, host antimicrobials, and biocides. The frequent association of gdhR6 with the mtrR promoter mutation in these clinical isolates suggests that it has persisted in this genetic background to enhance lctP expression, thereby promoting virulence.
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2
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Cell-Free Protein Synthesis by Diversifying Bacterial Transcription Machinery. BIOTECH 2021; 10:biotech10040024. [PMID: 35822798 PMCID: PMC9245472 DOI: 10.3390/biotech10040024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 11/17/2022] Open
Abstract
We have evaluated several approaches to increase protein synthesis in a cell-free coupled bacterial transcription and translation system. A strong pargC promoter, originally isolated from a moderate thermophilic bacterium Geobacillus stearothermophilus, was used to improve the performance of a cell-free system in extracts of Escherichia coli BL21 (DE3). A stimulating effect on protein synthesis was detected with extracts prepared from recombinant cells, in which the E. coli RNA polymerase subunits α, β, β’ and ω are simultaneously coexpressed. Appending a 3′ UTR genomic sequence and a T7 transcription terminator to the protein-coding region also improves the synthetic activity of some genes from linear DNA. The E. coli BL21 (DE3) rna::Tn10 mutant deficient in a periplasmic RNase I was constructed. The mutant cell-free extract increases by up to four-fold the expression of bacterial and human genes mediated from both bacterial pargC and phage pT7 promoters. By contrast, the RNase E deficiency does not affect the cell-free expression of the same genes. The regulatory proteins of the extremophilic bacterium Thermotoga, synthesized in a cell-free system, can provide the binding capacity to target DNA regions. The advantageous characteristics of cell-free systems described open attractive opportunities for high-throughput screening assays.
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3
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Hasan MK, Dhungel BA, Govind R. Characterization of an operon required for growth on cellobiose in Clostridioides difficile. MICROBIOLOGY-SGM 2021; 167. [PMID: 34410904 DOI: 10.1099/mic.0.001079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cellobiose metabolism is linked to the virulence properties in numerous bacterial pathogens. Here, we characterized a putative cellobiose PTS operon of Clostridiodes difficile to investigate the role of cellobiose metabolism in C. difficile pathogenesis. Our gene knockout experiments demonstrated that the putative cellobiose operon enables uptake of cellobiose into C. difficile and allows growth when cellobiose is provided as the sole carbon source in minimal medium. Additionally, using reporter gene fusion assays and DNA pulldown experiments, we show that its transcription is regulated by CelR, a novel transcriptional repressor protein, which directly binds to the upstream region of the cellobiose operon to control its expression. We have also identified cellobiose metabolism to play a significant role in C. difficile physiology as observed by the reduction of sporulation efficiency when cellobiose uptake was compromised in the mutant strain. In corroboration to in vitro study findings, our in vivo hamster challenge experiment showed a significant reduction of pathogenicity by the cellobiose mutant strain in both the primary and the recurrent infection model - substantiating the role of cellobiose metabolism in C. difficile pathogenesis.
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Affiliation(s)
- Md Kamrul Hasan
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | | | - Revathi Govind
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
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4
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Almeida BC, Kaczmarek JA, Figueiredo PR, Prather KLJ, Carvalho ATP. Transcription factor allosteric regulation through substrate coordination to zinc. NAR Genom Bioinform 2021; 3:lqab033. [PMID: 33987533 PMCID: PMC8092373 DOI: 10.1093/nargab/lqab033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/30/2021] [Accepted: 04/08/2021] [Indexed: 11/14/2022] Open
Abstract
The development of new synthetic biology circuits for biotechnology and medicine requires deeper mechanistic insight into allosteric transcription factors (aTFs). Here we studied the aTF UxuR, a homodimer of two domains connected by a highly flexible linker region. To explore how ligand binding to UxuR affects protein dynamics we performed molecular dynamics simulations in the free protein, the aTF bound to the inducer D-fructuronate or the structural isomer D-glucuronate. We then validated our results by constructing a sensor plasmid for D-fructuronate in Escherichia coli and performed site-directed mutagenesis. Our results show that zinc coordination is necessary for UxuR function since mutation to alanines prevents expression de-repression by D-fructuronate. Analyzing the different complexes, we found that the disordered linker regions allow the N-terminal domains to display fast and large movements. When the inducer is bound, UxuR can sample an open conformation with a more pronounced negative charge at the surface of the N-terminal DNA binding domains. In opposition, in the free and D-glucuronate bond forms the protein samples closed conformations, with a more positive character at the surface of the DNA binding regions. These molecular insights provide a new basis to harness these systems for biological systems engineering.
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Affiliation(s)
- Beatriz C Almeida
- CNC-Center for Neuroscience and Cell Biology, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - Jennifer A Kaczmarek
- MIT-Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Pedro R Figueiredo
- CNC-Center for Neuroscience and Cell Biology, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - Kristala L J Prather
- MIT-Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alexandra T P Carvalho
- CNC-Center for Neuroscience and Cell Biology, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, 3004-504 Coimbra, Portugal
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5
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Horne CR, Venugopal H, Panjikar S, Wood DM, Henrickson A, Brookes E, North RA, Murphy JM, Friemann R, Griffin MDW, Ramm G, Demeler B, Dobson RCJ. Mechanism of NanR gene repression and allosteric induction of bacterial sialic acid metabolism. Nat Commun 2021; 12:1988. [PMID: 33790291 PMCID: PMC8012715 DOI: 10.1038/s41467-021-22253-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 03/03/2021] [Indexed: 12/20/2022] Open
Abstract
Bacteria respond to environmental changes by inducing transcription of some genes and repressing others. Sialic acids, which coat human cell surfaces, are a nutrient source for pathogenic and commensal bacteria. The Escherichia coli GntR-type transcriptional repressor, NanR, regulates sialic acid metabolism, but the mechanism is unclear. Here, we demonstrate that three NanR dimers bind a (GGTATA)3-repeat operator cooperatively and with high affinity. Single-particle cryo-electron microscopy structures reveal the DNA-binding domain is reorganized to engage DNA, while three dimers assemble in close proximity across the (GGTATA)3-repeat operator. Such an interaction allows cooperative protein-protein interactions between NanR dimers via their N-terminal extensions. The effector, N-acetylneuraminate, binds NanR and attenuates the NanR-DNA interaction. The crystal structure of NanR in complex with N-acetylneuraminate reveals a domain rearrangement upon N-acetylneuraminate binding to lock NanR in a conformation that weakens DNA binding. Our data provide a molecular basis for the regulation of bacterial sialic acid metabolism. The GntR superfamily is one of the largest families of transcription factors in prokaryotes. Here the authors combine biophysical analysis and structural biology to dissect the mechanism by which NanR — a GntR-family regulator — binds to its promoter to repress the transcription of genes necessary for sialic acid metabolism.
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Affiliation(s)
- Christopher R Horne
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Hariprasad Venugopal
- Clive and Vera Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, VIC, Australia
| | - Santosh Panjikar
- Australian Synchrotron, ANSTO, Clayton, VIC, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - David M Wood
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Amy Henrickson
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada
| | - Emre Brookes
- Department of Chemistry, University of Montana, Missoula, MT, USA
| | - Rachel A North
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Rosmarie Friemann
- Department of Clinical Microbiology, Sahlgrenska University Hospital, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden
| | - Michael D W Griffin
- Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, VIC, Australia
| | - Georg Ramm
- Clive and Vera Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, VIC, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada.,Department of Chemistry, University of Montana, Missoula, MT, USA
| | - Renwick C J Dobson
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand. .,Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, VIC, Australia.
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6
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Vigouroux A, Meyer T, Naretto A, Legrand P, Aumont-Nicaise M, Di Cicco A, Renoud S, Doré J, Lévy D, Vial L, Lavire C, Moréra S. Characterization of the first tetrameric transcription factor of the GntR superfamily with allosteric regulation from the bacterial pathogen Agrobacterium fabrum. Nucleic Acids Res 2021; 49:529-546. [PMID: 33313837 PMCID: PMC7797058 DOI: 10.1093/nar/gkaa1181] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 11/12/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022] Open
Abstract
A species-specific region, denoted SpG8-1b allowing hydroxycinnamic acids (HCAs) degradation is important for the transition between the two lifestyles (rhizospheric versus pathogenic) of the plant pathogen Agrobacterium fabrum. Indeed, HCAs can be either used as trophic resources and/or as induced-virulence molecules. The SpG8-1b region is regulated by two transcriptional regulators, namely, HcaR (Atu1422) and Atu1419. In contrast to HcaR, Atu1419 remains so far uncharacterized. The high-resolution crystal structures of two fortuitous citrate complexes, two DNA complexes and the apoform revealed that the tetrameric Atu1419 transcriptional regulator belongs to the VanR group of Pfam PF07729 subfamily of the large GntR superfamily. Until now, GntR regulators were described as dimers. Here, we showed that Atu1419 represses three genes of the HCAs catabolic pathway. We characterized both the effector and DNA binding sites and identified key nucleotides in the target palindrome. From promoter activity measurement using defective gene mutants, structural analysis and gel-shift assays, we propose N5,N10-methylenetetrahydrofolate as the effector molecule, which is not a direct product/substrate of the HCA degradation pathway. The Zn2+ ion present in the effector domain has both a structural and regulatory role. Overall, our work shed light on the allosteric mechanism of transcription employed by this GntR repressor.
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Affiliation(s)
- Armelle Vigouroux
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Thibault Meyer
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Anaïs Naretto
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Pierre Legrand
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - Magali Aumont-Nicaise
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Aurélie Di Cicco
- Sorbonne Université, Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, 26 rue d’Ulm, 75005 Paris, France
| | - Sébastien Renoud
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Jeanne Doré
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Daniel Lévy
- Sorbonne Université, Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, 26 rue d’Ulm, 75005 Paris, France
| | - Ludovic Vial
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Céline Lavire
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Solange Moréra
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
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7
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Molecular Cloning, Purification and Characterization of Mce1R of Mycobacterium tuberculosis. Mol Biotechnol 2021; 63:200-220. [PMID: 33423211 DOI: 10.1007/s12033-020-00293-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/18/2020] [Indexed: 10/22/2022]
Abstract
The mce1 operon of Mycobacterium tuberculosis, important for lipid metabolism/transport, host cell invasion, modulation of host immune response and pathogenicity, is under the transcriptional control of Mce1R. Hence characterizing Mce1R is an important step for novel anti-tuberculosis drug discovery. The present study reports functional and in silico characterization of Mce1R. In this work, we have computationally modeled the structure of Mce1R and have validated the structure by computational and experimental methods. Mce1R has been shown to harbor the canonical VanR-like structure with a flexible N-terminal 'arm', carrying conserved positively charged residues, most likely involved in the operator DNA binding. The mce1R gene has been cloned, expressed, purified and its DNA-binding activity has been measured in vitro. The Kd value for Mce1R-operator DNA interaction has been determined to be 0.35 ± 0.02 µM which implies that Mce1R binds to DNA with moderate affinity compared to the other FCD family of regulators. So far, this is the first report for measuring the DNA-binding affinity of any VanR-type protein. Despite significant sequence similarity at the N-terminal domain, the wHTH motif of Mce1R exhibits poor conservancy of amino acid residues, critical for DNA-binding, thus results in moderate DNA-binding affinity. The N-terminal DNA-binding domain is structurally dynamic while the C-terminal domain showed significant stability and such profile of structural dynamics is most likely to be preserved in the structural orthologs of Mce1R. In addition to this, a cavity has been detected in the C-terminal domain of Mce1R which contains a few conserved residues. Comparison with other FCD family of regulators suggests that most of the conserved residues might be critical for binding to specific ligand. The max pKd value and drug score for the cavity are estimated to be 9.04 and 109 respectively suggesting that the cavity represents a suitable target site for novel anti-tuberculosis drug discovery approaches.
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8
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Lin Z, Sun Y, Liu Y, Tong S, Shang Z, Cai Y, Lin W. Structural and Functional Analyses of the Transcription Repressor DgoR From Escherichia coli Reveal a Divalent Metal-Containing D-Galactonate Binding Pocket. Front Microbiol 2020; 11:590330. [PMID: 33224125 PMCID: PMC7674646 DOI: 10.3389/fmicb.2020.590330] [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: 08/01/2020] [Accepted: 10/20/2020] [Indexed: 11/21/2022] Open
Abstract
The transcription repressor of D-galactonate metabolism, DgoR, from Escherichia coli belongs to the FadR family of the GntR superfamily. In the presence of D-galactonate, DgoR binds to two inverted repeats overlapping the dgo cis-acting promoter repressing the expression of genes involved in D-galactonate metabolism. To further understand the structural and molecular details of ligand and effector interactions between D-galactonate and this FadR family member, herein we solved the crystal structure of C-terminal domain of DgoR (DgoR_C), which revealed a unique divalent metal-containing substrate binding pocket. The metal ion is required for D-galactonate binding, as evidenced by the dramatically decreased affinity between D-galactonate and DgoR in the presence of EDTA, which can be reverted by the addition of Zn2+, Mg2+, and Ca2+. The key amino acid residues involved in the interactions between D-galactonate and DgoR were revealed by molecular docking studies and further validated with biochemical studies by site-directed mutagenesis. It was found that changes to alanine in residues R102, W181, T191, and R224 resulted in significantly decreased binding affinities for D-galactonate, as determined by EMSA and MST assays. These results suggest that the molecular modifications induced by a D-galactonate and a metal binding in the DgoR are required for DNA binding activity and consequently, transcriptional inhibition.
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Affiliation(s)
- Zhaozhu Lin
- Department of Microbiology and Immunology, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yi Sun
- Department of Microbiology and Immunology, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yu Liu
- Department of Chemistry, Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ, United States
| | - Shujuan Tong
- Department of Microbiology and Immunology, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Zhuo Shang
- Department of Microbiology and Immunology, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yuanheng Cai
- Biochemistry and Cell Biology Department, Stony Brook University, Stony Brook, NY, United States
| | - Wei Lin
- Department of Microbiology and Immunology, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China.,State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.,Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing, China
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9
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How to outwit nature: Omics insight into butanol tolerance. Biotechnol Adv 2020; 46:107658. [PMID: 33220435 DOI: 10.1016/j.biotechadv.2020.107658] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 12/16/2022]
Abstract
The energy crisis, depletion of oil reserves, and global climate changes are pressing problems of developed societies. One possibility to counteract that is microbial production of butanol, a promising new fuel and alternative to many petrochemical reagents. However, the high butanol toxicity to all known microbial species is the main obstacle to its industrial implementation. The present state of the art review aims to expound the recent advances in modern omics approaches to resolving this insurmountable to date problem of low butanol tolerance. Genomics, transcriptomics, and proteomics show that butanol tolerance is a complex phenomenon affecting multiple genes and their expression. Efflux pumps, stress and multidrug response, membrane transport, and redox-related genes are indicated as being most important during butanol challenge, in addition to fine-tuning of global regulators of transcription (Spo0A, GntR), which may further improve tolerance. Lipidomics shows that the alterations in membrane composition (saturated lipids and plasmalogen increase) are very much species-specific and butanol-related. Glycomics discloses the pleiotropic effect of CcpA, the role of alternative sugar transport, and the production of exopolysaccharides as alternative routes to overcoming butanol stress. Unfortunately, the strain that simultaneously syntheses and tolerates butanol in concentrations that allow its commercialization has not yet been discovered or produced. Omics insight will allow the purposeful increase of butanol tolerance in natural and engineered producers and the effective heterologous expression of synthetic butanol pathways in strains hereditary butanol-resistant up to 3.2 - 4.9% (w/v). Future breakthrough can be achieved by a detailed study of the membrane proteome, of which 21% are proteins with unknown functions.
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10
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Arya G, Pal M, Sharma M, Singh B, Singh S, Agrawal V, Chaba R. Molecular insights into effector binding by DgoR, a GntR/FadR family transcriptional repressor of D-galactonate metabolism in Escherichia coli. Mol Microbiol 2020; 115:591-609. [PMID: 33068046 DOI: 10.1111/mmi.14625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 01/23/2023]
Abstract
Several GntR/FadR transcriptional regulators govern sugar acid metabolism in bacteria. Although effectors have been identified for a few sugar acid regulators, the mode of effector binding is unknown. Even in the overall FadR subfamily, there are limited details on effector-regulator interactions. Here, we identified the effector-binding cavity in Escherichia coli DgoR, a FadR subfamily transcriptional repressor of D-galactonate metabolism that employs D-galactonate as its effector. Using a genetic screen, we isolated several dgoR superrepressor alleles. Blind docking suggested eight amino acids corresponding to these alleles to form a part of the effector-binding cavity. In vivo and in vitro assays showed that these mutations compromise the inducibility of DgoR without affecting its oligomeric status or affinity for target DNA. Taking Bacillus subtilis GntR as a representative, we demonstrated that the effector-binding cavity is similar among FadR subfamily sugar acid regulators. Finally, a comparison of sugar acid regulators with other FadR members suggested conserved features of effector-regulator recognition within the FadR subfamily. Sugar acid metabolism is widely implicated in bacterial colonization and virulence. The present study sets the basis to investigate the influence of natural genetic variations in FadR subfamily regulators on their sensitivity to sugar acids and ultimately on host-bacterial interactions.
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Affiliation(s)
- Garima Arya
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Mohinder Pal
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Monika Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, India
| | - Bhupinder Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Swati Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Vishal Agrawal
- Department of Biochemistry, Panjab University, Chandigarh, India
| | - Rachna Chaba
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
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11
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Ambri F, D’Ambrosio V, Di Blasi R, Maury J, Jacobsen SAB, McCloskey D, Jensen MK, Keasling JD. High-Resolution Scanning of Optimal Biosensor Reporter Promoters in Yeast. ACS Synth Biol 2020; 9:218-226. [PMID: 31935067 DOI: 10.1021/acssynbio.9b00333] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Small-molecule binding allosteric transcription factors (aTFs) derived from bacteria enable real-time monitoring of metabolite abundances, high-throughput screening of genetic designs, and dynamic control of metabolism. Yet, engineering of reporter promoter designs of prokaryotic aTF biosensors in eukaryotic cells is complex. Here we investigate the impact of aTF binding site positions at single-nucleotide resolution in >300 reporter promoter designs in Saccharomyces cerevisiae. From this we identify biosensor output landscapes with transient and distinct aTF binding site position effects for aTF repressors and activators, respectively. Next, we present positions for tunable reporter promoter outputs enabling metabolite-responsive designs for a total of four repressor-type and three activator-type aTF biosensors with dynamic output ranges up to 8- and 26-fold, respectively. This study highlights aTF binding site positions in reporter promoters as key for successful biosensor engineering and that repressor-type aTF biosensors allows for more flexibility in terms of choice of binding site positioning compared to activator-type aTF biosensors.
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Affiliation(s)
- Francesca Ambri
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Vasil D’Ambrosio
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Roberto Di Blasi
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Jerome Maury
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | | | - Douglas McCloskey
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Michael K. Jensen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Jay. D Keasling
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
- Joint BioEnergy Institute, Emeryville, California 94608, United States
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Chemical and Biomolecular Engineering & Department of Bioengineering, University of California, Berkeley, California 94720, United States
- Center for Synthetic Biochemistry, Institute for Synthetic Biology, Shenzhen Institutes of Advanced Technologies, Shenzhen 518055, China
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12
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D'Ambrosio V, Pramanik S, Goroncy K, Jakočiūnas T, Schönauer D, Davari MD, Schwaneberg U, Keasling JD, Jensen MK. Directed evolution of VanR biosensor specificity in yeast. ACTA ACUST UNITED AC 2020. [DOI: 10.1016/j.biotno.2020.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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13
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Transcriptional regulation of a gonococcal gene encoding a virulence factor (L-lactate permease). PLoS Pathog 2019; 15:e1008233. [PMID: 31860664 PMCID: PMC6957213 DOI: 10.1371/journal.ppat.1008233] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 01/13/2020] [Accepted: 11/22/2019] [Indexed: 12/16/2022] Open
Abstract
GdhR is a GntR-type regulator of Neisseria gonorrhoeae encoded by a gene (gdhR) belonging to the MtrR regulon, which comprises multiple genes required for antibiotic resistance such as the mtrCDE efflux pump genes. In previous work we showed that loss of gdhR results in enhanced gonococcal fitness in a female mouse model of lower genital tract infection. Here, we used RNA-Seq to perform a transcriptional profiling study to determine the GdhR regulon. GdhR was found to regulate the expression of 2.3% of all the genes in gonococcal strain FA19, of which 39 were activated and 11 were repressed. Within the GdhR regulon we found that lctP, which encodes a unique L-lactate transporter and has been associated with gonococcal pathogenesis, was the highest of GdhR-repressed genes. By using in vitro transcription and DNase I footpriting assays we mapped the lctP transcriptional start site (TSS) and determined that GdhR directly inhibits transcription by binding to an inverted repeat sequence located 9 bases downstream of the lctP TSS. Epistasis analysis revealed that, while loss of lctP increased susceptibility of gonococci to hydrogen peroxide (H2O2) the loss of gdhR enhanced resistance; however, this GdhR-endowed property was reversed in a double gdhR lctP null mutant. We assessed the effect of different carbon sources on lctP expression and found that D-glucose, but not L-lactate or pyruvate, repressed lctP expression within a physiological concentration range but in a GdhR-independent manner. Moreover, we found that adding glucose to the medium enhanced susceptibility of gonococci to hydrogen peroxide. We propose a model for the role of lctP regulation via GdhR and glucose in the pathogenesis of N. gonorrhoeae.
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14
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Kotowska M, Świat M, Zarȩba-Pasławska J, Jaworski P, Pawlik K. A GntR-Like Transcription Factor HypR Regulates Expression of Genes Associated With L-Hydroxyproline Utilization in Streptomyces coelicolor A3(2). Front Microbiol 2019; 10:1451. [PMID: 31297104 PMCID: PMC6608401 DOI: 10.3389/fmicb.2019.01451] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 06/11/2019] [Indexed: 11/13/2022] Open
Abstract
Bacteria from the genus Streptomyces have been long exploited as the most prolific producers of antibiotics, other secondary metabolites and enzymes. They are important members of soil microbial communities that can adapt to changing conditions thank to the fine regulation of gene expression in response to environmental signals. Streptomyces coelicolor A3(2) is a model organism for molecular studies with the most deeply recognized interactions within the complex metabolic and regulatory network. However, details about molecular signals recognized by specialized regulatory proteins as well as their direct targets are often missing. We describe here a zinc-binding protein HypR (SCO6294) which belongs to FadR subfamily of GntR-like regulators. The DNA sequence 5'-TACAATGTCAC-3' recognized by the HypR protein in its own promoter region was identified by DNase I footprinting. Binding of six DNA fragments containing similar sequences located in other promoter regions were confirmed by the electrophoretic mobility shift assay (EMSA). The sequences of 7 in vitro-determined binding sites were assembled to generate a logo of the HypR binding motif, 5'-CTNTGC(A/C)ATGTCAC-3'. Comparison of luciferase reporter genes expression under the control of cloned promoter regions in S. coelicolor A3(2) wild type and deletion mutant strains revealed, that the HypR protein acts as a repressor of its target genes. Genes belonging to the regulon of HypR code for enzymes putatively involved in collagen degradation and utilization of L-hydroxyproline (L-Hyp) as concluded from predicted structure and conserved domains. Their transcription is induced in the wild type strain by the addition of L-Hyp to the culture medium. Moreover, knockout of one of the genes from the predicted L-Hyp utilization operon abolished the ability of the strain to grow on L-Hyp as a sole source of carbon. To our knowledge, this work is the first indication of the existence of the pathway of L-hydroxyproline catabolism in Streptomycetes.
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Affiliation(s)
- Magdalena Kotowska
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
| | | | | | | | - Krzysztof Pawlik
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
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15
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Identification of a GntR family regulator BusR Tha and its regulatory mechanism in the glycine betaine ABC transport system of Tetragenococcus halophilus. Extremophiles 2019; 23:451-460. [PMID: 31053934 DOI: 10.1007/s00792-019-01096-6] [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: 01/08/2019] [Accepted: 04/25/2019] [Indexed: 10/26/2022]
Abstract
Glycine betaine is one of the most effective compatible solutes of the halophilic lactic acid bacterium Tetragenococcus halophilus, the transportation of which is essential for its survival under salinity stress condition. In the current study, we attempted to define a glycine betaine ABC transporter system of T. halophilus, busATha, which plays an important role in adapting to salinity condition. The expression of busATha enhanced the growth of the recombinant strain under high salinity. BusRTha, a transcription regulator that represses the expression of busATha, was characterized, and the repression was abrogated under high salinity. The binding of the regulator was demonstrated through electrophoretic mobility shift assays, and the binding sites were characterized as 5'-AAA(T/G)TGAC(C/A)(G/A)T(C/A)C-3'. This is the first studied transcription regulator of T. halophilus, and our findings provide insights into the molecular mechanism of halophilic life and tools for further application of halophiles as chassis in industrial biotechnology.
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16
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Pinheiro J, Lisboa J, Pombinho R, Carvalho F, Carreaux A, Brito C, Pöntinen A, Korkeala H, dos Santos NM, Morais-Cabral JH, Sousa S, Cabanes D. MouR controls the expression of the Listeria monocytogenes Agr system and mediates virulence. Nucleic Acids Res 2018; 46:9338-9352. [PMID: 30011022 PMCID: PMC6182135 DOI: 10.1093/nar/gky624] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 06/25/2018] [Accepted: 06/28/2018] [Indexed: 12/11/2022] Open
Abstract
The foodborne pathogen Listeria monocytogenes (Lm) causes invasive infection in susceptible animals and humans. To survive and proliferate within hosts, this facultative intracellular pathogen tightly coordinates the expression of a complex regulatory network that controls the expression of virulence factors. Here, we identified and characterized MouR, a novel virulence regulator of Lm. Through RNA-seq transcriptomic analysis, we determined the MouR regulon and demonstrated how MouR positively controls the expression of the Agr quorum sensing system (agrBDCA) of Lm. The MouR three-dimensional structure revealed a dimeric DNA-binding transcription factor belonging to the VanR class of the GntR superfamily of regulatory proteins. We also showed that by directly binding to the agr promoter region, MouR ultimately modulates chitinase activity and biofilm formation. Importantly, we demonstrated by in vitro cell invasion assays and in vivo mice infections the role of MouR in Lm virulence.
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Affiliation(s)
- Jorge Pinheiro
- Group of Molecular Microbiology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
- ICBAS- Instituto de Ciências Biomédicas Abel Salazar, University of Porto, Porto 4200-135, Portugal
| | - Johnny Lisboa
- Group of Fish Immunology & Vaccinology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
| | - Rita Pombinho
- Group of Molecular Microbiology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
- ICBAS- Instituto de Ciências Biomédicas Abel Salazar, University of Porto, Porto 4200-135, Portugal
| | - Filipe Carvalho
- Group of Molecular Microbiology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
- ICBAS- Instituto de Ciências Biomédicas Abel Salazar, University of Porto, Porto 4200-135, Portugal
| | - Alexis Carreaux
- Group of Molecular Microbiology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
- SDV - UFR Sciences Du Vivant: Université Paris Diderot-Paris 7, Paris 75013, France
| | - Cláudia Brito
- Group of Molecular Microbiology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
- ICBAS- Instituto de Ciências Biomédicas Abel Salazar, University of Porto, Porto 4200-135, Portugal
| | - Anna Pöntinen
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki 00014, Finland
| | - Hannu Korkeala
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki 00014, Finland
| | - Nuno M S dos Santos
- Group of Fish Immunology & Vaccinology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
| | - João H Morais-Cabral
- Group of Structural Biochemistry, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
| | - Sandra Sousa
- Group of Molecular Microbiology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
| | - Didier Cabanes
- Group of Molecular Microbiology, IBMC – Institute for Molecular and Cell Biology; i3S – Institute for Research and Innovation in Health, Porto 4200-135, Portugal
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17
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da Costa WLO, Araújo CLDA, Dias LM, Pereira LCDS, Alves JTC, Araújo FA, Folador EL, Henriques I, Silva A, Folador ARC. Functional annotation of hypothetical proteins from the Exiguobacterium antarcticum strain B7 reveals proteins involved in adaptation to extreme environments, including high arsenic resistance. PLoS One 2018; 13:e0198965. [PMID: 29940001 PMCID: PMC6016940 DOI: 10.1371/journal.pone.0198965] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 05/28/2018] [Indexed: 02/07/2023] Open
Abstract
Exiguobacterium antarcticum strain B7 is a psychrophilic Gram-positive bacterium that possesses enzymes that can be used for several biotechnological applications. However, many proteins from its genome are considered hypothetical proteins (HPs). These functionally unknown proteins may indicate important functions regarding the biological role of this bacterium, and the use of bioinformatics tools can assist in the biological understanding of this organism through functional annotation analysis. Thus, our study aimed to assign functions to proteins previously described as HPs, present in the genome of E. antarcticum B7. We used an extensive in silico workflow combining several bioinformatics tools for function annotation, sub-cellular localization and physicochemical characterization, three-dimensional structure determination, and protein-protein interactions. This genome contains 2772 genes, of which 765 CDS were annotated as HPs. The amino acid sequences of all HPs were submitted to our workflow and we successfully attributed function to 132 HPs. We identified 11 proteins that play important roles in the mechanisms of adaptation to adverse environments, such as flagellar biosynthesis, biofilm formation, carotenoids biosynthesis, and others. In addition, three predicted HPs are possibly related to arsenic tolerance. Through an in vitro assay, we verified that E. antarcticum B7 can grow at high concentrations of this metal. The approach used was important to precisely assign function to proteins from diverse classes and to infer relationships with proteins with functions already described in the literature. This approach aims to produce a better understanding of the mechanism by which this bacterium adapts to extreme environments and to the finding of targets with biotechnological interest.
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Affiliation(s)
- Wana Lailan Oliveira da Costa
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Institute of Biological Science, Federal University of Para, Belém, Pará, Brazil
| | - Carlos Leonardo de Aragão Araújo
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Institute of Biological Science, Federal University of Para, Belém, Pará, Brazil
| | - Larissa Maranhão Dias
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Institute of Biological Science, Federal University of Para, Belém, Pará, Brazil
| | - Lino César de Sousa Pereira
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Institute of Biological Science, Federal University of Para, Belém, Pará, Brazil
| | - Jorianne Thyeska Castro Alves
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Institute of Biological Science, Federal University of Para, Belém, Pará, Brazil
| | - Fabrício Almeida Araújo
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Institute of Biological Science, Federal University of Para, Belém, Pará, Brazil
| | - Edson Luiz Folador
- Biotechnology Center, Federal University of Paraiba, João Pessoa, Paraíba, Brazil
| | - Isabel Henriques
- Biology Department & CESAM, University of Aveiro, Aveiro, Portugal
| | - Artur Silva
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Institute of Biological Science, Federal University of Para, Belém, Pará, Brazil
| | - Adriana Ribeiro Carneiro Folador
- Laboratory of Genomic and Bioinformatics, Center of Genomics and System Biology, Institute of Biological Science, Federal University of Para, Belém, Pará, Brazil
- * E-mail: ,
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18
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Metallochaperones and metalloregulation in bacteria. Essays Biochem 2017; 61:177-200. [PMID: 28487396 DOI: 10.1042/ebc20160076] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 02/23/2017] [Accepted: 02/27/2017] [Indexed: 12/21/2022]
Abstract
Bacterial transition metal homoeostasis or simply 'metallostasis' describes the process by which cells control the intracellular availability of functionally required metal cofactors, from manganese (Mn) to zinc (Zn), avoiding both metal deprivation and toxicity. Metallostasis is an emerging aspect of the vertebrate host-pathogen interface that is defined by a 'tug-of-war' for biologically essential metals and provides the motivation for much recent work in this area. The host employs a number of strategies to starve the microbial pathogen of essential metals, while for others attempts to limit bacterial infections by leveraging highly competitive metals. Bacteria must be capable of adapting to these efforts to remodel the transition metal landscape and employ highly specialized metal sensing transcriptional regulators, termed metalloregulatory proteins,and metallochaperones, that allocate metals to specific destinations, to mediate this adaptive response. In this essay, we discuss recent progress in our understanding of the structural mechanisms and metal specificity of this adaptive response, focusing on energy-requiring metallochaperones that play roles in the metallocofactor active site assembly in metalloenzymes and metallosensors, which govern the systems-level response to metal limitation and intoxication.
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19
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Labella JI, Obrebska A, Espinosa J, Salinas P, Forcada-Nadal A, Tremiño L, Rubio V, Contreras A. Expanding the Cyanobacterial Nitrogen Regulatory Network: The GntR-Like Regulator PlmA Interacts with the PII-PipX Complex. Front Microbiol 2016; 7:1677. [PMID: 27840625 PMCID: PMC5083789 DOI: 10.3389/fmicb.2016.01677] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/06/2016] [Indexed: 11/17/2022] Open
Abstract
Cyanobacteria, phototrophic organisms that perform oxygenic photosynthesis, perceive nitrogen status by sensing 2-oxoglutarate levels. PII, a widespread signaling protein, senses and transduces nitrogen and energy status to target proteins, regulating metabolism and gene expression. In cyanobacteria, under conditions of low 2-oxoglutarate, PII forms complexes with the enzyme N-acetyl glutamate kinase, increasing arginine biosynthesis, and with PII-interacting protein X (PipX), making PipX unavailable for binding and co-activation of the nitrogen regulator NtcA. Both the PII-PipX complex structure and in vivo functional data suggested that this complex, as such, could have regulatory functions in addition to PipX sequestration. To investigate this possibility we performed yeast three-hybrid screening of genomic libraries from Synechococcus elongatus PCC7942, searching for proteins interacting simultaneously with PII and PipX. The only prey clone found in the search expressed PlmA, a member of the GntR family of transcriptional regulators proven here by gel filtration to be homodimeric. Interactions analyses further confirmed the simultaneous requirement of PII and PipX, and showed that the PlmA contacts involve PipX elements exposed in the PII-PipX complex, specifically the C-terminal helices and one residue of the tudor-like body. In contrast, PII appears not to interact directly with PlmA, possibly being needed indirectly, to induce an extended conformation of the C-terminal helices of PipX and for modulating the surface polarity at the PII-PipX boundary, two elements that appear crucial for PlmA binding. Attempts to inactive plmA confirmed that this gene is essential in S. elongatus. Western blot assays revealed that S. elongatus PlmA, irrespective of the nitrogen regime, is a relatively abundant transcriptional regulator, suggesting the existence of a large PlmA regulon. In silico studies showed that PlmA is universally and exclusively found in cyanobacteria. Based on interaction data, on the relative amounts of the proteins involved in PII-PipX-PlmA complexes, determined in western assays, and on the restrictions imposed by the symmetries of trimeric PII and dimeric PlmA molecules, a structural and regulatory model for PlmA function is discussed in the context of the cyanobacterial nitrogen interaction network.
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Affiliation(s)
- Jose I Labella
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante Alicante, Spain
| | - Anna Obrebska
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante Alicante, Spain
| | - Javier Espinosa
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante Alicante, Spain
| | - Paloma Salinas
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante Alicante, Spain
| | | | - Lorena Tremiño
- Instituto de Biomedicina de Valencia of the CSIC Valencia, Spain
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia of the CSICValencia, Spain; Group 739, CIBER de Enfermedades Raras (CIBERER-ISCIII)Valencia, Spain
| | - Asunción Contreras
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante Alicante, Spain
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20
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Blancato VS, Pagliai FA, Magni C, Gonzalez CF, Lorca GL. Functional Analysis of the Citrate Activator CitO from Enterococcus faecalis Implicates a Divalent Metal in Ligand Binding. Front Microbiol 2016; 7:101. [PMID: 26903980 PMCID: PMC4746285 DOI: 10.3389/fmicb.2016.00101] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 01/19/2016] [Indexed: 02/04/2023] Open
Abstract
The regulator of citrate metabolism, CitO, from Enterococcus faecalis belongs to the FCD family within the GntR superfamily. In the presence of citrate, CitO binds to cis-acting sequences located upstream of the cit promoters inducing the expression of genes involved in citrate utilization. The quantification of the molecular binding affinities, performed by isothermal titration calorimetry (ITC), indicated that CitO has a high affinity for citrate (KD = 1.2 ± 0.2 μM), while it did not recognize other metabolic intermediates. Based on a structural model of CitO where a putative small molecule and a metal binding site were identified, it was hypothesized that the metal ion is required for citrate binding. In agreement with this model, citrate binding to CitO sharply decreased when the protein was incubated with EDTA. This effect was reverted by the addition of Ni2+, and Zn2+ to a lesser extent. Structure-based site-directed mutagenesis was conducted and it was found that changes to alanine in residues Arg97 and His191 resulted in decreased binding affinities for citrate, as determined by EMSA and ITC. Further assays using lacZ fusions confirmed that these residues in CitO are involved in sensing citrate in vivo. These results indicate that the molecular modifications induced by a ligand and a metal binding in the C-terminal domain of CitO are required for optimal DNA binding activity, and consequently, transcriptional activation.
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Affiliation(s)
- Víctor S Blancato
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular de Rosario, Consejo Nacional de Investigaciones Científicas y TécnicasRosario, Argentina; Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of FloridaGainesville, FL, USA
| | - Fernando A Pagliai
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of Florida Gainesville, FL, USA
| | - Christian Magni
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas Rosario, Argentina
| | - Claudio F Gonzalez
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of Florida Gainesville, FL, USA
| | - Graciela L Lorca
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of Florida Gainesville, FL, USA
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21
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Tutukina MN, Potapova AV, Vlasov PK, Purtov YA, Ozoline ON. Structural modeling of the ExuR and UxuR transcription factors of E. coli: search for the ligands affecting their regulatory properties. J Biomol Struct Dyn 2016; 34:2296-304. [DOI: 10.1080/07391102.2015.1115779] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Maria N. Tutukina
- Institute of Cell Biophysics Russian Academy of Sciences, Institutskaya str., 3, Pushchino, Moscow Region 142290, Russia
| | - Anna V. Potapova
- Institute of Cell Biophysics Russian Academy of Sciences, Institutskaya str., 3, Pushchino, Moscow Region 142290, Russia
| | - Peter K. Vlasov
- Centre for Genomic Regulation (CRG) and Universitat Pompeu Fabra (UPF), C/Dr. Aiguader, 88, Barcelona 08003, Spain
| | - Yuri A. Purtov
- Institute of Cell Biophysics Russian Academy of Sciences, Institutskaya str., 3, Pushchino, Moscow Region 142290, Russia
| | - Olga N. Ozoline
- Institute of Cell Biophysics Russian Academy of Sciences, Institutskaya str., 3, Pushchino, Moscow Region 142290, Russia
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22
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Jain D. Allosteric control of transcription in GntR family of transcription regulators: A structural overview. IUBMB Life 2015; 67:556-63. [PMID: 26172911 DOI: 10.1002/iub.1401] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 06/17/2015] [Indexed: 01/24/2023]
Abstract
The GntR family of transcription regulators constitutes one of the most abundant family of transcription factors. These modulators are involved in a variety of mechanisms controlling various metabolic processes. GntR family members are typically two domain proteins with a smaller N-terminus domain (NTD) with conserved architecture of winged-helix-turn-helix (wHTH) for DNA binding and a larger C-terminus domain (CTD) or the effector binding domain which is also involved in oligomerization. Interestingly, the CTD shows structural heterogeneity depending upon the type of effector molecule that it binds and displays structural homology to various classes of proteins. Binding of the effector molecule to the CTD brings about a conformational change in the transcription factor such that its affinity for its cognate DNA sequence is altered. This review summarizes the structural information available on the members of GntR family and discusses the common features of the DNA binding and operator recognition within the family. The variation in the allosteric mechanism employed by the members of this family is also discussed.
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Affiliation(s)
- Deepti Jain
- Transcription Regulation Laboratory Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, Haryana, India
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23
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Suvorova IA, Korostelev YD, Gelfand MS. GntR Family of Bacterial Transcription Factors and Their DNA Binding Motifs: Structure, Positioning and Co-Evolution. PLoS One 2015; 10:e0132618. [PMID: 26151451 PMCID: PMC4494728 DOI: 10.1371/journal.pone.0132618] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/16/2015] [Indexed: 12/03/2022] Open
Abstract
The GntR family of transcription factors (TFs) is a large group of proteins present in diverse bacteria and regulating various biological processes. Here we use the comparative genomics approach to reconstruct regulons and identify binding motifs of regulators from three subfamilies of the GntR family, FadR, HutC, and YtrA. Using these data, we attempt to predict DNA-protein contacts by analyzing correlations between binding motifs in DNA and amino acid sequences of TFs. We identify pairs of positions with high correlation between amino acids and nucleotides for FadR, HutC, and YtrA subfamilies and show that the most predicted DNA-protein interactions are quite similar in all subfamilies and conform well to the experimentally identified contacts formed by FadR from E. coli and AraR from B. subtilis. The most frequent predicted contacts in the analyzed subfamilies are Arg-G, Asn-A, Asp-C. We also analyze the divergon structure and preferred site positions relative to regulated genes in the FadR and HutC subfamilies. A single site in a divergon usually regulates both operons and is approximately in the middle of the intergenic area. Double sites are either involved in the co-operative regulation of both operons and then are in the center of the intergenic area, or each site in the pair independently regulates its own operon and tends to be near it. We also identify additional candidate TF-binding boxes near palindromic binding sites of TFs from the FadR, HutC, and YtrA subfamilies, which may play role in the binding of additional TF-subunits.
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Affiliation(s)
- Inna A. Suvorova
- Research and Training Center on Bioinformatics, Institute for Information Transmission Problems RAS (The Kharkevich Institute), Moscow, Russia
- * E-mail:
| | - Yuri D. Korostelev
- Research and Training Center on Bioinformatics, Institute for Information Transmission Problems RAS (The Kharkevich Institute), Moscow, Russia
| | - Mikhail S. Gelfand
- Research and Training Center on Bioinformatics, Institute for Information Transmission Problems RAS (The Kharkevich Institute), Moscow, Russia
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia
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24
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Lord DM, Uzgoren Baran A, Soo VWC, Wood TK, Peti W, Page R. McbR/YncC: implications for the mechanism of ligand and DNA binding by a bacterial GntR transcriptional regulator involved in biofilm formation. Biochemistry 2014; 53:7223-31. [PMID: 25376905 PMCID: PMC4245980 DOI: 10.1021/bi500871a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
MqsR-controlled
colanic acid and biofilm regulator (McbR, also
known as YncC) is the protein product of a highly induced gene in
early Escherichia coli biofilm development
and has been regarded as an attractive target for blocking biofilm
formation. This protein acts as a repressor for genes involved in
exopolysaccharide production and an activator for genes involved in
stress response. To better understand the role of McbR in governing
the switch from exponential growth to the biofilm state, we determined
the crystal structure of McbR to 2.1 Å. The structure reveals
McbR to be a member of the FadR C-terminal domain (FCD) family of
the GntR superfamily of transcriptional regulators (this family was
named after the first identified member, GntR, a transcriptional repressor
of the gluconate operon of Bacillus subtilis). Previous to this study, only six of the predicted 2800 members
of this family had been structurally characterized. Here, we identify
the residues that constitute the McbR effector and DNA binding sites.
In addition, comparison of McbR with other members of the FCD domain
family shows that this family of proteins adopts highly distinct oligomerization
interfaces, which has implications for DNA binding and regulation.
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Affiliation(s)
- Dana M Lord
- Department of Molecular Biology, Cell Biology and Biochemistry, ‡Graduate Program in Molecular Pharmacology and Physiology, and §Department of Molecular Pharmacology, Physiology and Biotechnology & Chemistry, Brown University , Providence, Rhode Island 02903, United States
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Rao M, Liu H, Yang M, Zhao C, He ZG. A copper-responsive global repressor regulates expression of diverse membrane-associated transporters and bacterial drug resistance in mycobacteria. J Biol Chem 2012; 287:39721-31. [PMID: 23014988 DOI: 10.1074/jbc.m112.383604] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sequencing of entire bacterial genomes has led to the identification of many membrane-associated transporters, including several multidrug resistance transport proteins, in recent years. However, the regulators and signaling pathways involved in the expression of these genes remain largely unknown. In this study, we have identified Ms2173, a GntR/FadR family transcription factor, as a novel global regulator in Mycobacterium smegmatis. Ms2173 was found to specifically recognize a 15-bp palindromic motif and to broadly regulate expression of 292 genes, including 37 genes that encode membrane-associated transport proteins. Copper ions induced Ms2173 to form inactive proteins lacking DNA-binding activity. Ms2173 was shown to function as a repressor of its target genes. Interestingly, we found that the function of Ms2173 was linked to mycobacterial drug resistance. Compared with the substantially enhanced drug resistance in the Ms2173-deleted mutant strain, the strains overexpressing Ms2173 were more sensitive to anti-tuberculosis drugs than the wild-type strain. Additionally, copper ions could partially counteract the in vivo function of Ms2173. We have thus characterized the first mycobacterial GntR/Fad-like transcription factor that functions as a copper ion-responsive global repressor that we have renamed GfcR. These findings further enhance our understanding of membrane-associated transporter regulation and drug resistance in mycobacteria.
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Affiliation(s)
- Muding Rao
- National Key Laboratory of Agricultural Microbiology, Center for Proteomics Research, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
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Abstract
The intracellular availability of all biologically required transition metal ions in bacteria, e.g., Zn, Cu, Fe, as well as the detoxification of nonbiological heavy metal pollutants, is controlled at the molecular level by a panel of metalloregulatory or "metal sensor" proteins. Metal sensor proteins are specialized allosteric proteins that regulate the transcription of genes linked to transition metal homeostasis as a result of direct binding of a single metal ion or two closely related metal ions, to the exclusion of all others. In many cases, the binding of the cognate metal ion induces a structural change in a metal sensor oligomer that either activates or inhibits operator DNA binding. A quantitative measure of the degree to which a particular metal drives metalloregulation of transcription is the allosteric coupling-free energy, ΔG(c). In this chapter, we outline detailed spectroscopically derived methods for measuring metal binding affinity, K(Me), as well as ΔG(c) independent of K(Me), presented in the context of a simple coupled equilibrium scheme. Studies carried out in this way provide quantitative insights into the degree to which a particular metal ion is capable of driving allosteric switching, and via ligand substitution, the extent to which individual coordination bonds establish structural linkage of allosteric metal and operator DNA-binding sites.
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Cooper DR, Grelewska K, Kim CY, Joachimiak A, Derewenda ZS. The structure of DinB from Geobacillus stearothermophilus: a representative of a unique four-helix-bundle superfamily. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:219-24. [PMID: 20208147 PMCID: PMC2833023 DOI: 10.1107/s1744309109053913] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 12/14/2009] [Indexed: 03/23/2024]
Abstract
The crystal structure of the dinB gene product from Geobacillus stearothermophilus (GsDinB) is reported at 2.5 A resolution. The dinB gene is one of the DNA-damage-induced genes and the corresponding protein, DinB, is the founding member of a Pfam family with no known function. The protein contains a four-helix up-down-down-up bundle that has previously been described in the literature in three disparate proteins: the enzyme MDMPI (mycothiol-dependent maleylpyruvate isomerase), YfiT and TTHA0303, a member of a small DUF (domain of unknown function). However, a search of the DALI structural database revealed similarities to a further 11 new unpublished structures contributed by structural genomics centers. The sequences of these proteins are quite divergent and represent several Pfam families, yet their structures are quite similar and most (but not all) seem to have the ability to coordinate a metal ion using a conserved histidine-triad motif. The structural similarities of these diverse proteins suggest that a new Pfam clan encompassing the families that share this fold should be created. The proteins that share this fold exhibit four different quaternary structures: monomeric and three different dimeric forms.
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Affiliation(s)
- David R. Cooper
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
- The Integrated Center for Structure and Function Innovation (ISFI), USA
| | - Katarzyna Grelewska
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
- The Integrated Center for Structure and Function Innovation (ISFI), USA
| | - Chang-Yub Kim
- The Integrated Center for Structure and Function Innovation (ISFI), USA
- Bioscience Division, Los Alamos National Laboratory, USA
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Zygmunt S. Derewenda
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
- The Integrated Center for Structure and Function Innovation (ISFI), USA
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