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Moreno-Blanco A, Pluta R, Espinosa M, Ruiz-Cruz S, Bravo A. Promoter DNA recognition by the Enterococcus faecalis global regulator MafR. Front Mol Biosci 2023; 10:1294974. [PMID: 38192335 PMCID: PMC10773906 DOI: 10.3389/fmolb.2023.1294974] [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: 09/15/2023] [Accepted: 11/30/2023] [Indexed: 01/10/2024] Open
Abstract
When Enterococcus faecalis is exposed to changing environmental conditions, the expression of many genes is regulated at the transcriptional level. We reported previously that the enterococcal MafR protein causes genome-wide changes in the transcriptome. Here we show that MafR activates directly the transcription of the OG1RF_10478 gene, which encodes a hypothetical protein of 111 amino acid residues. We have identified the P10478 promoter and demonstrated that MafR enhances the efficiency of this promoter by binding to a DNA site that contains the -35 element. Moreover, our analysis of the OG1RF_10478 protein AlphaFold model indicates high similarity to 1) structures of EIIB components of the bacterial phosphoenolpyruvate:carbohydrate phosphotransferase system, and 2) structures of receiver domains that are found in response regulators of two-component signal transduction systems. However, unlike typical EIIB components, OG1RF_10478 lacks a Cys or His residue at the conserved phosphorylation site, and, unlike typical receiver domains, OG1RF_10478 lacks a conserved Asp residue at the position usually required for phosphorylation. Different from EIIB components and receiver domains, OG1RF_10478 contains an insertion between residues 10 and 30 that, according to ColabFold prediction, may serve as a dimerization interface. We propose that OG1RF_10478 could participate in regulatory functions by protein-protein interactions.
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Affiliation(s)
- Ana Moreno-Blanco
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Radoslaw Pluta
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Sofía Ruiz-Cruz
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Alicia Bravo
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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Bravo A, Moreno-Blanco A, Espinosa M. One Earth: The Equilibrium between the Human and the Bacterial Worlds. Int J Mol Sci 2023; 24:15047. [PMID: 37894729 PMCID: PMC10606248 DOI: 10.3390/ijms242015047] [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: 08/17/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/29/2023] Open
Abstract
Misuse and abuse of antibiotics on humans, cattle, and crops have led to the selection of multi-resistant pathogenic bacteria, the most feared 'superbugs'. Infections caused by superbugs are progressively difficult to treat, with a subsequent increase in lethality: the toll on human lives is predicted to reach 10 million by 2050. Here we review three concepts linked to the growing resistance to antibiotics, namely (i) the Resistome, which refers to the collection of bacterial genes that confer resistance to antibiotics, (ii) the Mobilome, which includes all the mobile genetic elements that participate in the spreading of antibiotic resistance among bacteria by horizontal gene transfer processes, and (iii) the Nichome, which refers to the set of genes that are expressed when bacteria try to colonize new niches. We also discuss the strategies that can be used to tackle bacterial infections and propose an entente cordiale with the bacterial world so that instead of war and destruction of the 'fierce enemy' we can achieve a peaceful coexistence (the One Earth concept) between the human and the bacterial worlds. This, in turn, will contribute to microbial biodiversity, which is crucial in a globally changing climate due to anthropogenic activities.
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Affiliation(s)
- Alicia Bravo
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, E-28040 Madrid, Spain
| | | | - Manuel Espinosa
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, E-28040 Madrid, Spain
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Moreno-Blanco A, Solano-Collado V, Ortuno-Camuñas A, Espinosa M, Ruiz-Cruz S, Bravo A. PclR is a transcriptional activator of the gene that encodes the pneumococcal collagen-like protein PclA. Sci Rep 2022; 12:11827. [PMID: 35821046 PMCID: PMC9276737 DOI: 10.1038/s41598-022-15758-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 06/29/2022] [Indexed: 11/09/2022] Open
Abstract
The Gram-positive bacterium Streptococcus pneumoniae is a major human pathogen that shows high levels of genetic variability. The pneumococcal R6 genome harbours several gene clusters that are not present in all strains of the species. One of these clusters contains two divergent genes, pclA, which encodes a putative surface-exposed protein that contains large regions of collagen-like repeats, and spr1404 (here named pclR). PclA was shown to mediate pneumococcal adherence to host cells in vitro. In this work, we demonstrate that PclR (494 amino acids) is a transcriptional activator. It stimulates transcription of the pclA gene by binding to a specific DNA site upstream of the core promoter. In addition, we show that PclR has common features with the MgaSpn transcriptional regulator (493 amino acids), which is also encoded by the R6 genome. These proteins have high sequence similarity (60.3%), share the same organization of predicted functional domains, and generate multimeric complexes on linear double-stranded DNAs. However, on the PpclA promoter region, MgaSpn binds to a site different from the one recognized by PclR. Our results indicate that PclR and MgaSpn have similar DNA-binding properties but different DNA-binding specificities, pointing to a different regulatory role of both proteins.
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Affiliation(s)
- Ana Moreno-Blanco
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Virtu Solano-Collado
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain.,Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Alejandro Ortuno-Camuñas
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Sofía Ruiz-Cruz
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain. .,School of Microbiology, University College Cork and APC Microbiome Ireland, Western Road, Cork, T12 YT20, Ireland.
| | - Alicia Bravo
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain.
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Rom JS, Hart MT, McIver KS. PRD-Containing Virulence Regulators (PCVRs) in Pathogenic Bacteria. Front Cell Infect Microbiol 2021; 11:772874. [PMID: 34737980 PMCID: PMC8560693 DOI: 10.3389/fcimb.2021.772874] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/04/2021] [Indexed: 01/02/2023] Open
Abstract
Bacterial pathogens rely on a complex network of regulatory proteins to adapt to hostile and nutrient-limiting host environments. The phosphoenolpyruvate phosphotransferase system (PTS) is a conserved pathway in bacteria that couples transport of sugars with phosphorylation to monitor host carbohydrate availability. A family of structurally homologous PTS-regulatory-domain-containing virulence regulators (PCVRs) has been recognized in divergent bacterial pathogens, including Streptococcus pyogenes Mga and Bacillus anthracis AtxA. These paradigm PCVRs undergo phosphorylation, potentially via the PTS, which impacts their dimerization and their activity. Recent work with predicted PCVRs from Streptococcus pneumoniae (MgaSpn) and Enterococcus faecalis (MafR) suggest they interact with DNA like nucleoid-associating proteins. Yet, Mga binds to promoter sequences as a homo-dimeric transcription factor, suggesting a bi-modal interaction with DNA. High-resolution crystal structures of 3 PCVRs have validated the domain structure, but also raised additional questions such as how ubiquitous are PCVRs, is PTS-mediated histidine phosphorylation via potential PCVRs widespread, do specific sugars signal through PCVRs, and do PCVRs interact with DNA both as transcription factors and nucleoid-associating proteins? Here, we will review known and putative PCVRs based on key domain and functional characteristics and consider their roles as both transcription factors and possibly chromatin-structuring proteins.
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Affiliation(s)
- Joseph S Rom
- Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, United States
| | - Meaghan T Hart
- Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, United States
| | - Kevin S McIver
- Cell Biology & Molecular Genetics, University of Maryland, College Park, MD, United States.,Maryland Pathogen Research Institute, University of Maryland, College Park, MD, United States
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Li J, Wang J, Ruiz-Cruz S, Espinosa M, Zhang JR, Bravo A. In vitro DNA Inversions Mediated by the PsrA Site-Specific Tyrosine Recombinase of Streptococcus pneumoniae. Front Mol Biosci 2020; 7:43. [PMID: 32266289 PMCID: PMC7096588 DOI: 10.3389/fmolb.2020.00043] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 02/28/2020] [Indexed: 11/17/2022] Open
Abstract
Site-specific recombination is a DNA breaking and reconstructing process that plays important roles in various cellular pathways for both prokaryotes and eukaryotes. This process requires a site-specific recombinase and direct or inverted repeats. Some tyrosine site-specific recombinases catalyze DNA inversions and regulate subpopulation diversity and phase variation in many bacterial species. In Streptococcus pneumoniae, the PsrA tyrosine recombinase was shown to control DNA inversions in the three DNA methyltransferase hsdS genes of the type I restriction-modification cod locus. Such DNA inversions are mediated by three inverted repeats (IR1, IR2, and IR3). In this work, we purified an untagged form of the PsrA protein and studied its DNA-binding and catalytic features. Gel retardation assays showed that PsrA binds to linear and supercoiled DNAs, containing or not inverted repeats. Nevertheless, DNase I footprinting assays showed that, on linear DNAs, PsrA has a preference for sites that include an IR1 sequence (IR1.1 or IR1.2) and its boundary sequences. Furthermore, on supercoiled DNAs, PsrA was able to generate DNA inversions between specific inverted repeats (IR1, IR2, and IR3), which supports its ability to locate specific target sites. Unlike other site-specific recombinases, PsrA showed reliance on magnesium ions for efficient catalysis of IR1-mediated DNA inversions. We discuss that PsrA might find its specific binding sites on the bacterial genome by a mechanism that involves transitory non-specific interactions between protein and DNA.
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Affiliation(s)
- Jingwen Li
- Department of Basic Medical Science, Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Juanjuan Wang
- Department of Basic Medical Science, Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Sofía Ruiz-Cruz
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Jing-Ren Zhang
- Department of Basic Medical Science, Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Alicia Bravo
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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McCall RM, Sievers ME, Fattah R, Ghirlando R, Pomerantsev AP, Leppla SH. Bacillus anthracis Virulence Regulator AtxA Binds Specifically to the pagA Promoter Region. J Bacteriol 2019; 201:e00569-19. [PMID: 31570528 PMCID: PMC6832065 DOI: 10.1128/jb.00569-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 01/12/2023] Open
Abstract
Anthrax toxin activator (AtxA) is the master virulence gene regulator of Bacillus anthracis It regulates genes on the chromosome as well as the pXO1 and pXO2 plasmids. It is not clear how AtxA regulates these genes, and direct binding of AtxA to its targets has not been shown. It has been previously suggested that AtxA and other proteins in the Mga/AtxA global transcriptional regulators family bind to the curvature of their DNA targets, although this has never been experimentally proven. Using electrophoretic mobility shift assays, we demonstrate that AtxA binds directly to the promoter region of pagA upstream of the RNA polymerase binding site. We also demonstrate that in vitro, CO2 appears to have no role in AtxA binding. However, phosphomimetic and phosphoablative substitutions in the phosphotransferase system (PTS) regulation domains (PRDs) do appear to influence AtxA binding and pagA regulation. In silico, in vitro, and in vivo analyses demonstrate that one of two hypothesized stem-loops located upstream of the RNA polymerase binding site in the pagA promoter region is important for AtxA binding in vitro and pagA regulation in vivo Our study clarifies the mechanism by which AtxA interacts with one of its targets.IMPORTANCE Anthrax toxin activator (AtxA) regulates the major virulence genes in Bacillus anthracis The bacterium produces the anthrax toxins, and understanding the mechanism of toxin production may facilitate the development of therapeutics for B. anthracis infection. Since the discovery of AtxA 25 years ago, the mechanism by which it regulates its targets has largely remained a mystery. Here, we provide evidence that AtxA binds to the promoter region of the pagA gene encoding the main central protective antigen (PA) component of the anthrax toxin. These data suggest that AtxA binding plays a direct role in gene regulation. Our work also assists in clarifying the role of CO2 in AtxA's gene regulation and provides more evidence for the role of AtxA phosphorylation in virulence gene regulation.
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Affiliation(s)
- Rita M McCall
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Mary E Sievers
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Rasem Fattah
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Andrei P Pomerantsev
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Transcriptional activation by MafR, a global regulator of Enterococcus faecalis. Sci Rep 2019; 9:6146. [PMID: 30992530 PMCID: PMC6467988 DOI: 10.1038/s41598-019-42484-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 04/01/2019] [Indexed: 12/26/2022] Open
Abstract
Proteins that act as global transcriptional regulators play key roles in bacterial adaptation to new niches. These proteins recognize multiple DNA sites across the bacterial genome by different mechanisms. Enterococcus faecalis is able to survive in various niches of the human host, either as a commensal or as a leading cause of serious infections. Nonetheless, the regulatory pathways involved in its adaptive responses remain poorly understood. We reported previously that the MafR protein of E. faecalis causes genome-wide changes in the transcriptome. Here we demonstrate that MafR functions as a transcription activator. In vivo, MafR increased the activity of the P12294 and P11486 promoters and also the transcription levels of the two genes controlled by those promoters. These genes are predicted to encode a calcium-transporting P-type ATPase and a QueT transporter family protein, respectively. Thus, MafR could have a regulatory role in calcium homeostasis and queuosine synthesis. Furthermore, MafR recognized in vitro specific DNA sites that overlap the −35 element of each target promoter. The MafR binding sites exhibit a low sequence identity, suggesting that MafR uses a shape readout mechanism to achieve DNA-binding specificity.
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