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Barton IS, Ren Z, Cribb CB, Pitzer JE, Baglivo I, Martin DW, Wang X, Roop RM. Brucella MucR acts as an H-NS-like protein to silence virulence genes and structure the nucleoid. mBio 2023; 14:e0220123. [PMID: 37847580 PMCID: PMC10746212 DOI: 10.1128/mbio.02201-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 08/21/2023] [Indexed: 10/19/2023] Open
Abstract
IMPORTANCE Histone-like nucleoid structuring (H-NS) and H-NS-like proteins coordinate host-associated behaviors in many pathogenic bacteria, often through forming silencer/counter-silencer pairs with signal-responsive transcriptional activators to tightly control gene expression. Brucella and related bacteria do not encode H-NS or homologs of known H-NS-like proteins, and it is unclear if they have other proteins that perform analogous functions during pathogenesis. In this work, we provide compelling evidence for the role of MucR as a novel H-NS-like protein in Brucella. We show that MucR possesses many of the known functions attributed to H-NS and H-NS-like proteins, including the formation of silencer/counter-silencer pairs to control virulence gene expression and global structuring of the nucleoid. These results uncover a new role for MucR as a nucleoid structuring protein and support the importance of temporal control of gene expression in Brucella and related bacteria.
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Affiliation(s)
- Ian S. Barton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Zhongqing Ren
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Connor B. Cribb
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Joshua E. Pitzer
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Ilaria Baglivo
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania “Luigi Vanvitelli”, Caserta, Italy
| | - Daniel W. Martin
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Xindan Wang
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - R. Martin Roop
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
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2
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Castillo-Zeledón A, Rivas-Solano O, Villalta-Romero F, Gómez-Espinoza O, Moreno E, Chaves-Olarte E, Guzmán-Verri C. The Brucella abortus two-component system response regulator BvrR binds to three DNA regulatory boxes in the upstream region of omp25. Front Microbiol 2023; 14:1241143. [PMID: 37779712 PMCID: PMC10538546 DOI: 10.3389/fmicb.2023.1241143] [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: 06/16/2023] [Accepted: 08/15/2023] [Indexed: 10/03/2023] Open
Abstract
Brucella abortus is a facultative extracellular-intracellular bacterial zoonotic pathogen worldwide. It is also a major cause of abortion in bovines, generating economic losses. The two-component regulatory system BvrR/BvrS modulates the expression of genes required to transition from extracellular to intracellular lifestyles. However, few regulatory regions of BvrR direct target genes have been studied. In this study, we characterized the regulatory region of omp25, a gene encoding an outer membrane protein that is positively regulated by TCS BvrR/BvrS. By omp25-lacZ reporter fusions and β-galactosidase activity assays, we found that the region between-262 and + 127 is necessary for transcriptional activity, particularly a 111-bp long fragment located from-262 to -152. In addition, we demonstrated the binding of P-BvrR to three sites within the -140 to +1 region. Two of these sites were delimited between -18 to +1 and - 99 to -76 by DNase I footprinting and called DNA regulatory boxes 1 and 2, respectively. The third binding site (box 3) was delimited from -140 to -122 by combining EMSA and fluorescence anisotropy results. A molecular docking analysis with HDOCK predicted BvrR-DNA interactions between 11, 13, and 12 amino acid residue-nucleotide pairs in boxes 1, 2, and 3, respectively. A manual sequence alignment of the three regulatory boxes revealed the presence of inverted and non-inverted repeats of five to eight nucleotides, partially matching DNA binding motifs previously described for BvrR. We propose that P-BvrR binds directly to up to three regulatory boxes and probably interacts with other transcription factors to regulate omp25 expression. This gene regulation model could apply to other BvrR target genes and to orthologs of the TCS BvrR/BvrS and Omp25 in phylogenetically closed Rhizobiales.
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Affiliation(s)
- Amanda Castillo-Zeledón
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional de Costa Rica, Heredia, Costa Rica
| | - Olga Rivas-Solano
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional de Costa Rica, Heredia, Costa Rica
- Centro de Investigación en Biotecnología, Escuela de Biología, Instituto Tecnológico de Costa Rica, Campus Tecnológico Central Cartago, Cartago, Costa Rica
| | - Fabián Villalta-Romero
- Centro de Investigación en Biotecnología, Escuela de Biología, Instituto Tecnológico de Costa Rica, Campus Tecnológico Central Cartago, Cartago, Costa Rica
| | - Olman Gómez-Espinoza
- Centro de Investigación en Biotecnología, Escuela de Biología, Instituto Tecnológico de Costa Rica, Campus Tecnológico Central Cartago, Cartago, Costa Rica
| | - Edgardo Moreno
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional de Costa Rica, Heredia, Costa Rica
| | - Esteban Chaves-Olarte
- Centro de Investigación en Enfermedades Tropicales, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
| | - Caterina Guzmán-Verri
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional de Costa Rica, Heredia, Costa Rica
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3
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Li Y, Sun W, Wang Q, Yu Y, Wan Y, Zhou K, Guo R, Han X, Chen Z, Fang W, Jiang W. The GntR-like transcriptional regulator HutC involved in motility, biofilm-forming ability, and virulence in Vibrio parahaemolyticus. Microb Pathog 2022; 167:105546. [DOI: 10.1016/j.micpath.2022.105546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 06/12/2021] [Accepted: 04/15/2022] [Indexed: 12/19/2022]
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4
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Bialer MG, Ferrero MC, Delpino MV, Ruiz-Ranwez V, Posadas DM, Baldi PC, Zorreguieta A. Adhesive Functions or Pseudogenization of Type Va Autotransporters in Brucella Species. Front Cell Infect Microbiol 2021; 11:607610. [PMID: 33987105 PMCID: PMC8111173 DOI: 10.3389/fcimb.2021.607610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 04/01/2021] [Indexed: 01/18/2023] Open
Abstract
Adhesion to host cells is a key step for successful infection of many bacterial pathogens and may define tropism to different host tissues. To do so, bacteria display adhesins on their surfaces. Brucella is an intracellular pathogen capable of proliferating in a wide variety of cell types. It has been described that BmaC, a large protein that belongs to the classical (type Va) autotransporter family, is required for efficient adhesion of Brucella suis strain 1330 to epithelial cells and fibronectin. Here we show that B. suis 1330 harbors two other type Va autotransporters (BmaA and BmaB), which, although much smaller, share significant sequence similarities with BmaC and contain the essential domains to mediate proper protein translocation to the bacterial surface. Gain and loss of function studies indicated that BmaA, BmaB, and BmaC contribute, to a greater or lesser degree, to adhesion of B. suis 1330 to different cells such as synovial fibroblasts, osteoblasts, trophoblasts, and polarized epithelial cells as well as to extracellular matrix components. It was previously shown that BmaC localizes to a single bacterial pole. Interestingly, we observed here that, similar to BmaC, the BmaB adhesin is localized mostly at a single cell pole, reinforcing the hypothesis that Brucella displays an adhesive pole. Although Brucella species have strikingly similar genomes, they clearly differ in their host preferences. Mainly, the differences identified between species appear to be at loci encoding surface proteins. A careful in silico analysis of the putative type Va autotransporter orthologues from several Brucella strains showed that the bmaB locus from Brucella abortus and both, the bmaA and bmaC loci from Brucella melitensis are pseudogenes in all strains analyzed. Results reported here evidence that all three autotransporters play a role in the adhesion properties of B. suis 1330. However, Brucella spp. exhibit extensive variations in the repertoire of functional adhesins of the classical autotransporter family that can be displayed on the bacterial surface, making them an interesting target for future studies on host preference and tropism.
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Affiliation(s)
- Magalí G Bialer
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires, Argentina
| | - Mariana C Ferrero
- Facultad de Farmacia y Bioquímica, Cátedra de Inmunología, Universidad de Buenos Aires, Buenos Aires, Argentina.,Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - M Victoria Delpino
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | | | - Diana M Posadas
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires, Argentina
| | - Pablo C Baldi
- Facultad de Farmacia y Bioquímica, Cátedra de Inmunología, Universidad de Buenos Aires, Buenos Aires, Argentina.,Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Angeles Zorreguieta
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires, Argentina.,Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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5
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Roop RM, Barton IS, Hopersberger D, Martin DW. Uncovering the Hidden Credentials of Brucella Virulence. Microbiol Mol Biol Rev 2021; 85:e00021-19. [PMID: 33568459 PMCID: PMC8549849 DOI: 10.1128/mmbr.00021-19] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Bacteria in the genus Brucella are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. Brucella strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to Brucella pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.
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Affiliation(s)
- R Martin Roop
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Ian S Barton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Dariel Hopersberger
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Daniel W Martin
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
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6
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Rahbar MR, Zarei M, Jahangiri A, Khalili S, Nezafat N, Negahdaripour M, Fattahian Y, Savardashtaki A, Ghasemi Y. Non-adaptive Evolution of Trimeric Autotransporters in Brucellaceae. Front Microbiol 2020; 11:560667. [PMID: 33281759 PMCID: PMC7688925 DOI: 10.3389/fmicb.2020.560667] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 10/05/2020] [Indexed: 12/14/2022] Open
Abstract
Brucella species are Gram-negative, facultative intracellular pathogens. They are the main cause of brucellosis, which has led to a global health burden. Adherence of the pathogen to the host cells is the first step in the infection process. The bacteria can adhere to various biotic and abiotic surfaces using their outer membrane proteins. Trimeric autotransporter adhesins (TAAs) are modular homotrimers of various length and domain complexity. They are a diverse, and widespread gene family constituting the type Vc secretion pathway. These adhesins have been established as virulence factors in Brucellaceae. To date, no comprehensive and exhaustive study has been performed on the trimeric autotransporter family in the genus. In the present study, various bioinformatics tools were used to provide a novel evolutionary insight into the sequence and structure of this protein family in Brucellaceae. To this end, a dataset of all trimeric autotransporters from the Brucella genomes was built. Analyses included but were not limited to sequence alignment, phylogenetic tree constructions, codon-based test for selection, clustering of the sequences, and structure (primary to quaternary) predictions. Batch analyzes of the dataset suggested the existence of a few structural domains within the whole population. BatA from the B. abortus 2308 genome was selected as a reference to describe the features of these structural domains. Furthermore, we examined the structural basis for the observed rigidity and resiliency of the protein structure through a molecular dynamics evaluation, which led us to deduce that the random drift results in the non-adaptive evolution of the trimeric autotransporter genes in the Brucella genus. Notably, the modifications have occurred across the genus without interference of gene transmission.
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Affiliation(s)
- Mohammad Reza Rahbar
- Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mahboubeh Zarei
- Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Abolfazl Jahangiri
- Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Saeed Khalili
- Department of Biology Sciences, Shahid Rajaee Teacher Training University, Tehran, Iran
| | - Navid Nezafat
- Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Manica Negahdaripour
- Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Yaser Fattahian
- Department of Biotechnology, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran
| | - Amir Savardashtaki
- Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Younes Ghasemi
- Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
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7
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Bialer MG, Sycz G, Muñoz González F, Ferrero MC, Baldi PC, Zorreguieta A. Adhesins of Brucella: Their Roles in the Interaction with the Host. Pathogens 2020; 9:E942. [PMID: 33198223 PMCID: PMC7697752 DOI: 10.3390/pathogens9110942] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/03/2020] [Accepted: 11/05/2020] [Indexed: 01/30/2023] Open
Abstract
A central aspect of Brucella pathogenicity is its ability to invade, survive, and replicate in diverse phagocytic and non-phagocytic cell types, leading to chronic infections and chronic inflammatory phenomena. Adhesion to the target cell is a critical first step in the invasion process. Several Brucella adhesins have been shown to mediate adhesion to cells, extracellular matrix components (ECM), or both. These include the sialic acid-binding proteins SP29 and SP41 (binding to erythrocytes and epithelial cells, respectively), the BigA and BigB proteins that contain an Ig-like domain (binding to cell adhesion molecules in epithelial cells), the monomeric autotransporters BmaA, BmaB, and BmaC (binding to ECM components, epithelial cells, osteoblasts, synoviocytes, and trophoblasts), the trimeric autotransporters BtaE and BtaF (binding to ECM components and epithelial cells) and Bp26 (binding to ECM components). An in vivo role has also been shown for the trimeric autotransporters, as deletion mutants display decreased colonization after oral and/or respiratory infection in mice, and it has also been suggested for BigA and BigB. Several adhesins have shown unipolar localization, suggesting that Brucella would express an adhesive pole. Adhesin-based vaccines may be useful to prevent brucellosis, as intranasal immunization in mice with BtaF conferred high levels of protection against oral challenge with B. suis.
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Affiliation(s)
- Magalí G. Bialer
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires 1405, Argentina; (M.G.B.); (G.S.)
| | - Gabriela Sycz
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires 1405, Argentina; (M.G.B.); (G.S.)
| | - Florencia Muñoz González
- Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires 1113, Argentina; (F.M.G.); (M.C.F.)
- Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires 1113, Argentina
| | - Mariana C. Ferrero
- Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires 1113, Argentina; (F.M.G.); (M.C.F.)
- Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires 1113, Argentina
| | - Pablo C. Baldi
- Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires 1113, Argentina; (F.M.G.); (M.C.F.)
- Instituto de Estudios de la Inmunidad Humoral (IDEHU), CONICET-Universidad de Buenos Aires, Buenos Aires 1113, Argentina
| | - Angeles Zorreguieta
- Fundación Instituto Leloir (FIL), IIBBA (CONICET-FIL), Buenos Aires 1405, Argentina; (M.G.B.); (G.S.)
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
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8
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Phenotypic characterization of trimeric autotransporter adhesin-defective bcaC mutant of Burkholderia cenocepacia: cross-talk towards the histidine kinase BCAM0218. Microbes Infect 2020; 22:457-466. [DOI: 10.1016/j.micinf.2020.05.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 05/28/2020] [Accepted: 05/29/2020] [Indexed: 11/22/2022]
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9
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Global Regulatory Roles of the Histidine-Responsive Transcriptional Repressor HutC in Pseudomonas fluorescens SBW25. J Bacteriol 2020; 202:JB.00792-19. [PMID: 32291279 DOI: 10.1128/jb.00792-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/04/2020] [Indexed: 12/19/2022] Open
Abstract
HutC is known as a transcriptional repressor specific for histidine utilization (hut) genes in Gram-negative bacteria, including Pseudomonas fluorescens SBW25. However, its precise mode of protein-DNA interactions hasn't been examined with purified HutC proteins. Here, we performed electrophoretic mobility shift assay (EMSA) and DNase I footprinting using His6-tagged HutC and biotin-labeled probe of the hut promoter (PhutU). Results revealed a complex pattern of HutC oligomerization, and the specific protein-DNA interaction is disrupted by urocanate, a histidine derivative, in a concentration-dependent manner. Next, we searched for putative HutC-binding sites in the SBW25 genome. This led to the identification of 143 candidate targets with a P value less than 10-4 HutC interaction with eight selected candidate sites was subsequently confirmed by EMSA analysis, including the type IV pilus assembly protein PilZ, phospholipase C (PlcC) for phosphatidylcholine hydrolyzation, and key regulators of cellular nitrogen metabolism (NtrBC and GlnE). Finally, an isogenic hutC deletion mutant was subjected to transcriptome sequencing (RNA-seq) analysis and phenotypic characterization. When bacteria were grown on succinate and histidine, hutC deletion caused upregulation of 794 genes and downregulation of 525 genes at a P value of <0.05 with a fold change cutoff of 2.0. The hutC mutant displayed an enhanced spreading motility and pyoverdine production in laboratory media, in addition to the previously reported growth defect on the surfaces of plants. Together, our data indicate that HutC plays global regulatory roles beyond histidine catabolism through low-affinity binding with operator sites located outside the hut locus.IMPORTANCE HutC in Pseudomonas is a representative member of the GntR/HutC family of transcriptional regulators, which possess a N-terminal winged helix-turn-helix (wHTH) DNA-binding domain and a C-terminal substrate-binding domain. HutC is generally known to repress expression of histidine utilization (hut) genes through binding to the PhutU promoter with urocanate (the first intermediate of the histidine degradation pathway) as the direct inducer. Here, we first describe the detailed molecular interactions between HutC and its PhutU target site in a plant growth-promoting bacterium, P. fluorescens SBW25, and further show that HutC possesses specific DNA-binding activities with many targets in the SBW25 genome. Subsequent RNA-seq analysis and phenotypic assays revealed an unexpected global regulatory role of HutC for successful bacterial colonization in planta.
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Bialer MG, Ruiz-Ranwez V, Sycz G, Estein SM, Russo DM, Altabe S, Sieira R, Zorreguieta A. MapB, the Brucella suis TamB homologue, is involved in cell envelope biogenesis, cell division and virulence. Sci Rep 2019; 9:2158. [PMID: 30770847 PMCID: PMC6377625 DOI: 10.1038/s41598-018-37668-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/05/2018] [Indexed: 01/18/2023] Open
Abstract
Brucella species are Gram-negative, facultative intracellular pathogens responsible for a worldwide zoonosis. The envelope of Brucella exhibits unique characteristics that make these bacteria furtive pathogens and resistant to several host defence compounds. We have identified a Brucella suis gene (mapB) that appeared to be crucial for cell envelope integrity. Indeed, the typical resistance of Brucella to both lysozyme and the cationic lipopeptide polymyxin B was markedly reduced in a ∆mapB mutant. MapB turned out to represent a TamB orthologue. This last protein, together with TamA, a protein belonging to the Omp85 family, form a complex that has been proposed to participate in the translocation of autotransporter proteins across the outer membrane (OM). Accordingly, we observed that MapB is required for proper assembly of an autotransporter adhesin in the OM, as most of the autotransporter accumulated in the mutant cell periplasm. Both assessment of the relative amounts of other specific outer membrane proteins (OMPs) and a proteome approach indicated that the absence of MapB did not lead to an extensive alteration in OMP abundance, but to a reduction in the relative amounts of a protein subset, including proteins from the Omp25/31 family. Electron microscopy revealed that ∆mapB cells exhibit multiple anomalies in cell morphology, indicating that the absence of the TamB homologue in B. suis severely affects cell division. Finally, ∆mapB cells were impaired in macrophage infection and showed an attenuated virulence phenotype in the mouse model. Collectively, our results indicate that the role of B. suis TamB homologue is not restricted to participating in the translocation of autotransporters across the OM but that it is essential for OM stability and protein composition and that it is involved in cell envelope biogenesis, a process that is inherently coordinated with cell division.
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Affiliation(s)
- Magalí Graciela Bialer
- Fundación Instituto Leloir, IIBBA-CONICET. Patricias Argentinas 435, (C1405BWE), Buenos Aires, Argentina
| | - Verónica Ruiz-Ranwez
- Fundación Instituto Leloir, IIBBA-CONICET. Patricias Argentinas 435, (C1405BWE), Buenos Aires, Argentina
| | - Gabriela Sycz
- Fundación Instituto Leloir, IIBBA-CONICET. Patricias Argentinas 435, (C1405BWE), Buenos Aires, Argentina
| | - Silvia Marcela Estein
- Laboratorio de Inmunología, Facultad de Ciencias Veterinarias, Centro de Investigación Veterinaria de Tandil (CIVETAN), CONICET-Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires (U.N.C.P.B.A), Tandil, Argentina
| | - Daniela Marta Russo
- Fundación Instituto Leloir, IIBBA-CONICET. Patricias Argentinas 435, (C1405BWE), Buenos Aires, Argentina
| | - Silvia Altabe
- Instituto de Biología Molecular y Celular de Rosario (IBR) and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Esmeralda y Ocampo, Rosario, Argentina
| | - Rodrigo Sieira
- Fundación Instituto Leloir, IIBBA-CONICET. Patricias Argentinas 435, (C1405BWE), Buenos Aires, Argentina
| | - Angeles Zorreguieta
- Fundación Instituto Leloir, IIBBA-CONICET. Patricias Argentinas 435, (C1405BWE), Buenos Aires, Argentina.
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
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11
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Kleinman CL, Sycz G, Bonomi HR, Rodríguez RM, Zorreguieta A, Sieira R. ChIP-seq analysis of the LuxR-type regulator VjbR reveals novel insights into the Brucella virulence gene expression network. Nucleic Acids Res 2017; 45:5757-5769. [PMID: 28334833 PMCID: PMC5449634 DOI: 10.1093/nar/gkx165] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 02/27/2017] [Accepted: 03/01/2017] [Indexed: 01/31/2023] Open
Abstract
LuxR-type transcription factors control diverse physiological functions necessary for bacterial adaptation to environmental changes. In the intracellular pathogen Brucella, the LuxR homolog VjbR has been shown to regulate the expression of virulence factors acting at early stages of the intracellular infection and, directly or indirectly, hundreds of additional genes. However, the precise determination of VjbR direct targets has so far proved elusive. Here, we performed chromatin immunoprecipitation of VjbR followed by next-generation sequencing (ChIP-seq). We detected a large amount of VjbR-binding sites distributed across the Brucella genome and determined a markedly asymmetric binding consensus motif, an unusual feature among LuxR-type regulators. RNA-seq analysis performed under conditions mimicking the eukaryotic intracellular environment revealed that, among all loci associated to VjbR-binding, this regulator directly modulated the expression of only a subset of genes encoding functions consistent with an intracellular adaptation strategy for survival during the initial stages of the host cell infection. Other VjbR-binding events, however, showed to be dissociated from transcription and may require different environmental signals to produce a transcriptional output. Taken together, our results bring new insights into the extent and functionality of LuxR-type-related transcriptional networks.
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Affiliation(s)
| | - Gabriela Sycz
- Fundación Instituto Leloir, Ciudad de Buenos Aires C1405BWE, Argentina
| | - Hernán R. Bonomi
- Fundación Instituto Leloir, Ciudad de Buenos Aires C1405BWE, Argentina
| | | | | | - Rodrigo Sieira
- Fundación Instituto Leloir, Ciudad de Buenos Aires C1405BWE, Argentina
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