1
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Alakavuklar MA, Fiebig A, Crosson S. The Brucella Cell Envelope. Annu Rev Microbiol 2023; 77:233-253. [PMID: 37104660 PMCID: PMC10787603 DOI: 10.1146/annurev-micro-032521-013159] [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] [Indexed: 04/29/2023]
Abstract
The cell envelope is a multilayered structure that insulates the interior of bacterial cells from an often chaotic outside world. Common features define the envelope across the bacterial kingdom, but the molecular mechanisms by which cells build and regulate this critical barrier are diverse and reflect the evolutionary histories of bacterial lineages. Intracellular pathogens of the genus Brucella exhibit marked differences in cell envelope structure, regulation, and biogenesis when compared to more commonly studied gram-negative bacteria and therefore provide an excellent comparative model for study of the gram-negative envelope. We review distinct features of the Brucella envelope, highlighting a conserved regulatory system that links cell cycle progression to envelope biogenesis and cell division. We further discuss recently discovered structural features of the Brucella envelope that ensure envelope integrity and that facilitate cell survival in the face of host immune stressors.
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Affiliation(s)
- Melene A Alakavuklar
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA;
| | - Aretha Fiebig
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA;
| | - Sean Crosson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA;
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2
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Cobián Güemes AG, Le T, Rojas MI, Jacobson NE, Villela H, McNair K, Hung SH, Han L, Boling L, Octavio JC, Dominguez L, Cantú VA, Archdeacon S, Vega AA, An MA, Hajama H, Burkeen G, Edwards RA, Conrad DJ, Rohwer F, Segall AM. Compounding Achromobacter Phages for Therapeutic Applications. Viruses 2023; 15:1665. [PMID: 37632008 PMCID: PMC10457797 DOI: 10.3390/v15081665] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/27/2023] [Accepted: 07/27/2023] [Indexed: 08/27/2023] Open
Abstract
Achromobacter species colonization of Cystic Fibrosis respiratory airways is an increasing concern. Two adult patients with Cystic Fibrosis colonized by Achromobacter xylosoxidans CF418 or Achromobacter ruhlandii CF116 experienced fatal exacerbations. Achromobacter spp. are naturally resistant to several antibiotics. Therefore, phages could be valuable as therapeutics for the control of Achromobacter. In this study, thirteen lytic phages were isolated and characterized at the morphological and genomic levels for potential future use in phage therapy. They are presented here as the Achromobacter Kumeyaay phage collection. Six distinct Achromobacter phage genome clusters were identified based on a comprehensive phylogenetic analysis of the Kumeyaay collection as well as the publicly available Achromobacter phages. The infectivity of all phages in the Kumeyaay collection was tested in 23 Achromobacter clinical isolates; 78% of these isolates were lysed by at least one phage. A cryptic prophage was induced in Achromobacter xylosoxidans CF418 when infected with some of the lytic phages. This prophage genome was characterized and is presented as Achromobacter phage CF418-P1. Prophage induction during lytic phage preparation for therapy interventions require further exploration. Large-scale production of phages and removal of endotoxins using an octanol-based procedure resulted in a phage concentrate of 1 × 109 plaque-forming units per milliliter with an endotoxin concentration of 65 endotoxin units per milliliter, which is below the Food and Drugs Administration recommended maximum threshold for human administration. This study provides a comprehensive framework for the isolation, bioinformatic characterization, and safe production of phages to kill Achromobacter spp. in order to potentially manage Cystic Fibrosis (CF) pulmonary infections.
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Affiliation(s)
- Ana Georgina Cobián Güemes
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Tram Le
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Maria Isabel Rojas
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Nicole E. Jacobson
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Helena Villela
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
- Marine Microbiomes Lab, Red Sea Research Center, King Abdullah University of Science and Technology, Building 2, Level 3, Room 3216 WS03, Thuwal 23955-6900, Saudi Arabia
| | - Katelyn McNair
- Computational Sciences Research Center, San Diego State University, San Diego, CA 92182, USA
| | - Shr-Hau Hung
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Lili Han
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
- Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Lance Boling
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Jessica Claire Octavio
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Lorena Dominguez
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Vito Adrian Cantú
- Computational Sciences Research Center, San Diego State University, San Diego, CA 92182, USA
| | - Sinéad Archdeacon
- College of Biological Sciences, University of California Davis, Davis, CA 95616, USA
| | - Alejandro A. Vega
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90025, USA
| | - Michelle A. An
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Hamza Hajama
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Gregory Burkeen
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Robert A. Edwards
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
- Computational Sciences Research Center, San Diego State University, San Diego, CA 92182, USA
- Flinders Accelerator for Microbiome Exploration, Flinders University, Sturt Road, Bedford Park 5042, Australia
| | - Douglas J. Conrad
- Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, University of California San Diego, San Diego, CA 9500, USA
| | - Forest Rohwer
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
| | - Anca M. Segall
- Department of Biology, Viral Information Institute, San Diego State University, San Diego, CA 92182, USA
- Computational Sciences Research Center, San Diego State University, San Diego, CA 92182, USA
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3
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The Ros/MucR Zinc-Finger Protein Family in Bacteria: Structure and Functions. Int J Mol Sci 2022; 23:ijms232415536. [PMID: 36555178 PMCID: PMC9779718 DOI: 10.3390/ijms232415536] [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: 11/18/2022] [Revised: 11/29/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
Ros/MucR is a widespread family of bacterial zinc-finger-containing proteins that integrate multiple functions, such as symbiosis, virulence, transcription regulation, motility, production of surface components, and various other physiological processes in cells. This regulatory protein family is conserved in bacteria and is characterized by its zinc-finger motif, which has been proposed as the ancestral domain from which the eukaryotic C2H2 zinc-finger structure has evolved. The first prokaryotic zinc-finger domain found in the transcription regulator Ros was identified in Agrobacterium tumefaciens. In the past decades, a large body of evidence revealed Ros/MucR as pleiotropic transcriptional regulators that mainly act as repressors through oligomerization and binding to AT-rich target promoters. The N-terminal domain and the zinc-finger-bearing C-terminal region of these regulatory proteins are engaged in oligomerization and DNA binding, respectively. These properties of the Ros/MucR proteins are similar to those of xenogeneic silencers, such as H-NS, MvaT, and Lsr2, which are mainly found in other lineages. In fact, a novel functional model recently proposed for this protein family suggests that they act as H-NS-'like' gene silencers. The prokaryotic zinc-finger domain exhibits interesting structural and functional features that are different from that of its eukaryotic counterpart (a βββα topology), as it folds in a significantly larger zinc-binding globular domain (a βββαα topology). Phylogenetic analysis of Ros/MucR homologs suggests an ancestral origin of this type of protein in α-Proteobacteria. Furthermore, multiple duplications and lateral gene transfer events contributing to the diversity and phyletic distribution of these regulatory proteins were found in bacterial genomes.
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Tartilán-Choya B, Sidhu-Muñoz RS, Vizcaíno N. The Transcriptional Regulator MucR, but Not Its Controlled Acid-Activated Chaperone HdeA, Is Essential for Virulence and Modulates Surface Architecture and Properties in Brucella ovis PA. Front Vet Sci 2022; 8:814752. [PMID: 35174240 PMCID: PMC8843074 DOI: 10.3389/fvets.2021.814752] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 12/16/2021] [Indexed: 11/13/2022] Open
Abstract
Brucella ovis is a non-zoonotic bacterium causing contagious epididymitis and other genital lesions in rams and responsible for significant economic losses in sheep-breeding areas. It is a naturally rough (without O-chains in the lipopolysaccharide) Brucella species whose virulence mechanisms have been less explored than those of zoonotic smooth brucellae (bearing O-chains that mask other outer membrane molecules). Considering the rough nature of Brucella ovis, the influence of surface components other than O-chains on its biological properties may be greater than in smooth Brucella species. Here we describe the construction and characterization of the mucR deletion mutant of virulent B. ovis PA, which is defective in a transcriptional regulator, affecting surface properties and virulence in smooth brucellae. This mutant showed increased amounts of three proteins identified as HdeA (acid-activated chaperone), Omp25d (outer membrane protein undetectable in the parental strain), and BOV_A0299 (hypothetical protein of unknown function). This observation correlated with the enhanced transcription of the corresponding genes and constitutes the first report on this type of proteome alteration in Brucella ΔmucR mutants. The upstream regions of the three genes contained AT rich domains with T-A steps described as binding sites for MucR in the Brucella abortus 2308 babR promoter (gene also upregulated in B. ovis ΔmucR), which suggests that hdeA, omp25d, and BOV_A0299 expression could be repressed by MucR through a direct binding to their promoter regions. Relative quantification of transcripts of several other genes selected according to the transcriptome of smooth brucellae ΔmucR mutants revealed not only similarities but also relevant differences among strains, such as those detected in flagellar and virB genes. Periplasmic HdeA has been related to the resistance of B. abortus to acidic pH, conditions encountered by Brucella inside phagocytes, but the deletion of hdeA in B. ovis PA and the ΔmucR mutant did not modify any of the evaluated properties of these strains. The B. ovis PA ΔmucR and ΔmucRΔhdeA mutants had defective in vitro growth and altered surface properties and architecture, exemplified by detectable amounts of Omp25d. Moreover, they showed virulence attenuation but established persistent splenic infection in mice, which encourages their evaluation as specifical attenuated vaccines against B. ovis.
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Affiliation(s)
| | - Rebeca S. Sidhu-Muñoz
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain
| | - Nieves Vizcaíno
- Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Salamanca, Spain
- *Correspondence: Nieves Vizcaíno
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5
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Quantification of Brucella abortus population structure in a natural host. Proc Natl Acad Sci U S A 2021; 118:2023500118. [PMID: 33688053 DOI: 10.1073/pnas.2023500118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cattle are natural hosts of the intracellular pathogen Brucella abortus, which inflicts a significant burden on the health and reproduction of these important livestock. The primary routes of infection in field settings have been described, but it is not known how the bovine host shapes the structure of B. abortus populations during infection. We utilized a library of uniquely barcoded B. abortus strains to temporally and spatially quantify population structure during colonization of cattle through a natural route of infection. Introducing 108 bacteria from this barcoded library to the conjunctival mucosa resulted in expected levels of local lymph node colonization at a 1-wk time point. We leveraged variance in strain abundance in the library to demonstrate that only 1 in 10,000 brucellae introduced at the site of infection reached a parotid lymph node. Thus, cattle restrict the overwhelming majority of B. abortus introduced via the ocular conjunctiva at this dose. Individual strains were spatially restricted within the host tissue, and the total B. abortus census was dominated by a small number of distinct strains in each lymph node. These results define a bottleneck that B. abortus must traverse to colonize local lymph nodes from the conjunctival mucosa. The data further support a model in which a small number of spatially isolated granulomas founded by unique strains are present at 1 wk postinfection. These experiments demonstrate the power of barcoded transposon tools to quantify infection bottlenecks and to define pathogen population structure in host tissues.
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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: 45] [Impact Index Per Article: 15.0] [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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7
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Zhou Y, Bu Z, Qian J, Chen Y, Qiao L, Yang S, Chen S, Wang X, Ren L, Yang Y. The UTP-glucose-1-phosphate uridylyltransferase of Brucella melitensis inhibits the activation of NF-κB via regulating the bacterial type IV secretion system. Int J Biol Macromol 2020; 164:3098-3104. [PMID: 32827613 DOI: 10.1016/j.ijbiomac.2020.08.134] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/12/2020] [Accepted: 08/17/2020] [Indexed: 02/06/2023]
Abstract
UDP-glucose pyrophosphorylase (UGPase) is an important pyrophosphatase that reversibly catalyzes the synthesis of UDP-glucose during glucose metabolism. We previously found that the deletion of UGPase may affect structure, growth, the virulence of Brucella, and the activation of cellular NF-κB. However, the exact mechanism of activation of NF-κB regulated by Brucella UGPase is still unclear. Here, we found for the first time that UGPase can regulate the expression of virB proteins (virB3, virB4, virB5, virB6, virB8, virB9, virB10, and virB11) of type IV secretion system (T4SS) as well as effectors (vceC, btpA, btpB, ricA, bspB, bspC, and bspF) of Brucella by promoting the expression of ribosomal S12 protein (rpsL), BMEI1825, and quinone of 2,4,5-trihydroxyphenylalanine (topA) proteins, and further inhibits the activation of cellular NF-κB and affects the virulence of Brucella. Our findings provide new insights into the mechanism used by Brucella to escape the immune recognition, which is expected to be of great value in the designing of Brucella vaccines and the screening of drug targets.
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Affiliation(s)
- Yucheng Zhou
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Wild Economic Animals and Plants, Chinese Academy of Agricultural Sciences, Changchun 130112, China
| | - Zhaoyang Bu
- Military Veterinary Institute, Academy of Military Medical Sciences, Changchun 130112, China
| | - Jing Qian
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Yuening Chen
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Wild Economic Animals and Plants, Chinese Academy of Agricultural Sciences, Changchun 130112, China
| | - Lianjiang Qiao
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Wild Economic Animals and Plants, Chinese Academy of Agricultural Sciences, Changchun 130112, China
| | - Sen Yang
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Wild Economic Animals and Plants, Chinese Academy of Agricultural Sciences, Changchun 130112, China
| | - Shipeng Chen
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Wild Economic Animals and Plants, Chinese Academy of Agricultural Sciences, Changchun 130112, China
| | - Xinglong Wang
- Military Veterinary Institute, Academy of Military Medical Sciences, Changchun 130112, China
| | - Linzhu Ren
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Yanling Yang
- State Key Laboratory for Molecular Biology of Special Economic Animals, Institute of Special Wild Economic Animals and Plants, Chinese Academy of Agricultural Sciences, Changchun 130112, China; Jilin Academy of Agricultural Sciences, Changchun 130033, China.
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8
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Brucella abortus Depends on l-Serine Biosynthesis for Intracellular Proliferation. Infect Immun 2020; 88:IAI.00840-19. [PMID: 31740531 DOI: 10.1128/iai.00840-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 11/11/2019] [Indexed: 01/15/2023] Open
Abstract
l-Serine is a nonessential amino acid and a key intermediate in several relevant metabolic pathways. In bacteria, the major source of l-serine is the phosphorylated pathway, which comprises three enzymes: d-3-phosphoglycerate dehydrogenase (PGDH; SerA), phosphoserine amino transferase (PSAT; SerC), and l-phosphoserine phosphatase (PSP; SerB). The Brucella abortus genome encodes two PGDHs (SerA-1 and SerA-2), involved in the first step in l-serine biosynthesis, and one PSAT and one PSP, responsible for the second and third steps, respectively. In this study, we demonstrate that the serA1 serA2 double mutant and the serC and serB single mutants are auxotrophic for l-serine. These auxotrophic mutants can be internalized but are unable to replicate in HeLa cells and in J774A.1 macrophage-like cells. Replication defects of auxotrophic mutants can be reverted by cell medium supplementation with l-serine at early times postinfection. In addition, the serB mutant is attenuated in the murine intraperitoneal infection model and has an altered lipid composition, since the lack of l-serine abrogates phosphatidylethanolamine synthesis in this strain. Taken together, these results reveal that limited availability of l-serine within the host cell impairs proliferation of the auxotrophic strains, highlighting the relevance of this biosynthetic pathway in Brucella pathogenicity.
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Identifying the region responsible for Brucella abortus MucR higher-order oligomer formation and examining its role in gene regulation. Sci Rep 2018; 8:17238. [PMID: 30467359 PMCID: PMC6250670 DOI: 10.1038/s41598-018-35432-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 11/05/2018] [Indexed: 11/09/2022] Open
Abstract
MucR is a member of the Ros/MucR family of prokaryotic zinc-finger proteins found in the α-proteobacteria which regulate the expression of genes required for the successful pathogenic and symbiotic interactions of these bacteria with the eukaryotic hosts. The structure and function of their distinctive zinc-finger domain has been well-studied, but only recently the quaternary structure of the full length proteins was investigated demonstrating their ability to form higher-order oligomers. The aim of this study was to identify the region of MucR involved in higher-order oligomer formation by analysing deletion and point mutants of this protein by Light Scattering, and to determine the role that MucR oligomerization plays in the regulatory function of this protein. Here we demonstrate that a conserved hydrophobic region at the N-terminus of MucR is responsible for higher-order oligomer formation and that MucR oligomerization is essential for its regulatory function in Brucella. All these features of MucR are shared by the histone-like nucleoid structuring protein, (H-NS), leading us to propose that the prokaryotic zinc-finger proteins in the MucR/Ros family control gene expression employing a mechanism similar to that used by the H-NS proteins, rather than working as classical transcriptional regulators.
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10
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Tian M, Lian Z, Bao Y, Bao S, Yin Y, Li P, Ding C, Wang S, Li T, Qi J, Wang X, Yu S. Identification of a novel, small, conserved hypothetical protein involved inBrucella abortusvirulence by modifying the expression of multiple genes. Transbound Emerg Dis 2018; 66:349-362. [DOI: 10.1111/tbed.13028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 09/05/2018] [Accepted: 09/21/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Mingxing Tian
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Zhengmin Lian
- China College of Veterinary Medicine Gansu Agricultural University LanzhouChina
| | - Yanqing Bao
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Shijun Bao
- China College of Veterinary Medicine Gansu Agricultural University LanzhouChina
| | - Yi Yin
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Peng Li
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Chan Ding
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Shaohui Wang
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Tao Li
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Jingjing Qi
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Xiaolan Wang
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
| | - Shengqing Yu
- Shanghai Veterinary Research Institute Chinese Academy of Agricultural Sciences (CAAS) Shanghai China
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11
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Patrick KL, Wojcechowskyj JA, Bell SL, Riba MN, Jing T, Talmage S, Xu P, Cabello AL, Xu J, Shales M, Jimenez-Morales D, Ficht TA, de Figueiredo P, Samuel JE, Li P, Krogan NJ, Watson RO. Quantitative Yeast Genetic Interaction Profiling of Bacterial Effector Proteins Uncovers a Role for the Human Retromer in Salmonella Infection. Cell Syst 2018; 7:323-338.e6. [PMID: 30077634 PMCID: PMC6160342 DOI: 10.1016/j.cels.2018.06.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/21/2018] [Accepted: 06/21/2018] [Indexed: 11/26/2022]
Abstract
Intracellular bacterial pathogens secrete a repertoire of effector proteins into host cells that are required to hijack cellular pathways and cause disease. Despite decades of research, the molecular functions of most bacterial effectors remain unclear. To address this gap, we generated quantitative genetic interaction profiles between 36 validated and putative effectors from three evolutionarily divergent human bacterial pathogens and 4,190 yeast deletion strains. Correlating effector-generated profiles with those of yeast mutants, we recapitulated known biology for several effectors with remarkable specificity and predicted previously unknown functions for others. Biochemical and functional validation in human cells revealed a role for an uncharacterized component of the Salmonella SPI-2 translocon, SseC, in regulating maintenance of the Salmonella vacuole through interactions with components of the host retromer complex. These results exhibit the power of genetic interaction profiling to discover and dissect complex biology at the host-pathogen interface.
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Affiliation(s)
- Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Jason A Wojcechowskyj
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Morgan N Riba
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Tao Jing
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Sara Talmage
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Pengbiao Xu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Ana L Cabello
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA; Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA; Norman Borlaug Center, Texas A&M University, College Station, TX 77843, USA
| | - Jiewei Xu
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA
| | - Michael Shales
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA
| | - David Jimenez-Morales
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA
| | - Thomas A Ficht
- Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA
| | - Paul de Figueiredo
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA; Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA; Norman Borlaug Center, Texas A&M University, College Station, TX 77843, USA
| | - James E Samuel
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA.
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA.
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12
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Transposon Sequencing of Brucella abortus Uncovers Essential Genes for Growth In Vitro and Inside Macrophages. Infect Immun 2018; 86:IAI.00312-18. [PMID: 29844240 DOI: 10.1128/iai.00312-18] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 05/22/2018] [Indexed: 12/28/2022] Open
Abstract
Brucella abortus is a class III zoonotic bacterial pathogen able to survive and replicate inside host cells, including macrophages. Here we report a multidimensional transposon sequencing analysis to identify genes essential for Brucella abortus growth in rich medium and replication in RAW 264.7 macrophages. The construction of a dense transposon mutant library and mapping of 929,769 unique mini-Tn5 insertion sites in the genome allowed identification of 491 essential coding sequences and essential segments in the B. abortus genome. Chromosome II carries a lower proportion (5%) of essential genes than chromosome I (19%), supporting the hypothesis of a recent acquisition of a megaplasmid as the origin of chromosome II. Temporally resolved transposon sequencing analysis as a function of macrophage infection stages identified 79 genes with a specific attenuation phenotype in macrophages, at either 2, 5, or 24 h postinfection, and 86 genes for which the attenuated mutant phenotype correlated with a growth defect on plates. We identified 48 genes required for intracellular growth, including the virB operon, encoding the type IV secretion system, which supports the validity of the screen. The remaining genes encode amino acid and pyrimidine biosynthesis, electron transfer systems, transcriptional regulators, and transporters. In particular, we report the need of an intact pyrimidine nucleotide biosynthesis pathway in order for B. abortus to proliferate inside RAW 264.7 macrophages.
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13
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Brucella Peptide Cross-Reactive Major Histocompatibility Complex Class I Presentation Activates SIINFEKL-Specific T Cell Receptor-Expressing T Cells. Infect Immun 2018; 86:IAI.00281-18. [PMID: 29735518 PMCID: PMC6013681 DOI: 10.1128/iai.00281-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 04/25/2018] [Indexed: 12/23/2022] Open
Abstract
Brucella spp. are intracellular pathogenic bacteria remarkable in their ability to escape immune surveillance and therefore inflict a state of chronic disease within the host. To enable further immune response studies, Brucella was engineered to express the well-characterized chicken ovalbumin (OVA). Surprisingly, we found that CD8 T cells bearing T cell receptors (TCR) nominally specific for the OVA peptide SIINFEKL (OT-1) reacted to parental Brucella-infected targets as well as OVA-expressing Brucella variants in cytotoxicity assays. Furthermore, splenocytes from Brucella-immunized mice produced gamma interferon (IFN-γ) and exhibited cytotoxicity in response to SIINFEKL-pulsed target cells.To determine if the SIINFEKL-reactive OT-1 TCR could be cross-reacting to Brucella peptides, we searched the Brucella proteome using an algorithm to generate a list of near-neighbor nonamer peptides that would bind to H2Kb. Selecting five Brucella peptide candidates, along with controls, we verified that several of these peptides mimicked SIINFEKL, resulting in T cell activation through the “SIINFEKL-specific” TCR. Activation was dependent on peptide concentration as well as sequence. Our results underscore the complexity and ubiquity of cross-reactivity in T cell recognition. This cross-reactivity may enable microbes such as Brucella to escape immune surveillance by presenting peptides similar to those of the host and may also lead to the activation of autoreactive T cells.
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14
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Jiang H, Dong H, Peng X, Feng Y, Zhu L, Niu K, Peng Y, Fan H, Ding J. Transcriptome analysis of gene expression profiling of infected macrophages between Brucella suis 1330 and live attenuated vaccine strain S2 displays mechanistic implication for regulation of virulence. Microb Pathog 2018; 119:241-247. [PMID: 29626657 DOI: 10.1016/j.micpath.2018.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/01/2018] [Accepted: 04/03/2018] [Indexed: 01/06/2023]
Abstract
Brucellosis is one of the most common zoonotic epidemics worldwide. Vaccination against brucellosis is an important control strategy to prevent the disease in many high-prevalence regions. At present, Brucella vaccine strain S2 is the most widely used vaccine in China. To uncover the mechanisms underlying virulence attenuation of S2, in this study we characterized the transcriptional profile of S2 and 1330 infected macrophages by transcriptome analysis. The results revealed that expressions of 440 genes were significantly different between macrophages infected by 1330 and S2. Data analysis showed that in the gene ontology term, the different expressed genes involved in innate immune response, phagoctyosis, recognition, and inflammatory response were significantly enriched. Pathway enrichment analysis indicated that the genes involved in transcriptional misregulation in cancer, staphylococcus aureus infection pathways and NF-kappa B signaling pathway were significantly affected. To reveal the molecular mechanisms related to different expression profiles of infected macrophages, the transcription levels of the different genes between the two bacterial genomes were detected. In total, the transcription of 29 different genes was significantly changed in either culture medium or infected microphages. The results of this study can be conducive to the promotion of better understanding of the related mechanisms underlying virulence attenuation of S2 and interactions between host cells and Brucella strains.
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Affiliation(s)
- Hui Jiang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China; China Institute of Veterinary Drug Control, Beijing, 102629, China
| | - Hao Dong
- China Animal Disease Control Center, Beijing, 102618, China
| | - Xiaowei Peng
- China Institute of Veterinary Drug Control, Beijing, 102629, China
| | - Yu Feng
- China Institute of Veterinary Drug Control, Beijing, 102629, China
| | - Liangquan Zhu
- China Institute of Veterinary Drug Control, Beijing, 102629, China
| | - Kai Niu
- College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Taian, Shandong, 271018, China
| | - Yong Peng
- China Institute of Veterinary Drug Control, Beijing, 102629, China
| | - Hongjie Fan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, China.
| | - Jiabo Ding
- China Institute of Veterinary Drug Control, Beijing, 102629, China.
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15
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Tian M, Bao Y, Li P, Hu H, Ding C, Wang S, Li T, Qi J, Wang X, Yu S. The putative amino acid ABC transporter substrate-binding protein AapJ2 is necessary for Brucella virulence at the early stage of infection in a mouse model. Vet Res 2018; 49:32. [PMID: 29598830 PMCID: PMC5874993 DOI: 10.1186/s13567-018-0527-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 03/12/2018] [Indexed: 01/17/2023] Open
Abstract
Brucellosis is a zoonotic bacterial disease caused by Brucella spp. The virulence of these bacteria is dependent on their ability to invade and replicate within host cells. In a previous study, a putative gene bab_RS27735 encoding an amino acid ABC transporter substrate-binding protein homologous to AapJ protein was found to be involved in Brucella abortus virulence. In this study, we successfully constructed a bab_RS27735 deletion mutant, Δ27735. Compared with the wild-type strain, the lipopolysaccharide pattern of the mutant was not changed, but the growth ability was slightly defected in the exponential phase. In tolerance tests, sensitivity of the Δ27735 mutant to oxidative stress, bactericidal peptides or low pH was not different from that of the wild-type strain. Cell infection assay showed that the mutant was reduced survival within macrophages but could efficiently escape lysosome degradation. The results of a virulence test showed that the Δ27735 mutant was attenuated in a mouse model at the early stage of infection but recovered its virulence at the late stage of infection. Meanwhile, the development of splenomegaly and histopathological lesions was observed in mice infected with either the wild-type strain or the mutant. These results are in line with the release of IL-12p40 and TNF-α into the peripheral blood of infected mice. Besides, expression of diverse genes was up-regulated in the Δ27735 mutant, which may contribute to the reduced virulence of the mutant. These data elucidated that the bab_RS27735 gene is necessary for B. abortus virulence at the early stage of infection in a mouse model.
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Affiliation(s)
- Mingxing Tian
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Yanqing Bao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Peng Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Hai Hu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Shaohui Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Tao Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Jingjing Qi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Xiaolan Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China
| | - Shengqing Yu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai, 200241, China.
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16
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De Y, Dong C, Cao Y, Wang X, Yang X, Wang N, Zhang C, Wang Z, Lyu Y, Wu Q. Genome-wide sequence transposon insertion sites and analyze the essential genes of Brucella melitensis. Microb Pathog 2017; 112:97-102. [PMID: 28888882 DOI: 10.1016/j.micpath.2017.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/03/2017] [Accepted: 09/05/2017] [Indexed: 12/29/2022]
Abstract
A transposon mutant library of B. melitensis NI including 32,640 transposon mutants was established. By sequencing the transposon insertion sites, 10,832 mutants were successfully defined for their insertion sites. Analysis of the mutants with defined transposon insertion sites (DTIS) indicated that the insertions were well spread through the two genomes. In addition, 948 genes with no detectable transposon insertions were taken as the candidate for identification of essential genes. In comparison with the Bacterial Database of Essential Genes and by using comparative genomics analysis, 183 potential essential genes of B. melitensis NI cultured in vitro were found and they were conserved in the common bacteria. This work was focused on screening of the essential genes of B. melitensis NI, which may provide a foundation for identification of the novel drug targets against brucellosis. Besides, the sequence-defined transposon library should serve as a resource for screening of different function genes of Brucella.
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Affiliation(s)
- Yanyan De
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Congyue Dong
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yanyang Cao
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xiaolei Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xiaowen Yang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Ning Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Cunrui Zhang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zhen Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yanli Lyu
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Qingmin Wu
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China.
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17
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Rossetti CA, Drake KL, Lawhon SD, Nunes JS, Gull T, Khare S, Adams LG. Systems Biology Analysis of Temporal In vivo Brucella melitensis and Bovine Transcriptomes Predicts host:Pathogen Protein-Protein Interactions. Front Microbiol 2017; 8:1275. [PMID: 28798726 PMCID: PMC5529337 DOI: 10.3389/fmicb.2017.01275] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 06/26/2017] [Indexed: 01/13/2023] Open
Abstract
To date, fewer than 200 gene-products have been identified as Brucella virulence factors, and most were characterized individually without considering how they are temporally and coordinately expressed or secreted during the infection process. Here, we describe and analyze the in vivo temporal transcriptional profile of Brucella melitensis during the initial 4 h interaction with cattle. Pathway analysis revealed an activation of the "Two component system" providing evidence that the in vivo Brucella sense and actively regulate their metabolism through the transition to an intracellular lifestyle. Contrarily, other Brucella pathways involved in virulence such as "ABC transporters" and "T4SS system" were repressed suggesting a silencing strategy to avoid stimulation of the host innate immune response very early in the infection process. Also, three flagellum-encoded loci (BMEII0150-0168, BMEII1080-1089, and BMEII1105-1114), the "flagellar assembly" pathway and the cell components "bacterial-type flagellum hook" and "bacterial-type flagellum" were repressed in the tissue-associated B. melitensis, while RopE1 sigma factor, a flagellar repressor, was activated throughout the experiment. These results support the idea that Brucella employ a stealthy strategy at the onset of the infection of susceptible hosts. Further, through systems-level in silico host:pathogen protein-protein interactions simulation and correlation of pathogen gene expression with the host gene perturbations, we identified unanticipated interactions such as VirB11::MAPK8IP1; BtaE::NFKBIA, and 22 kDa OMP precursor::BAD and MAP2K3. These findings are suggestive of new virulence factors and mechanisms responsible for Brucella evasion of the host's protective immune response and the capability to maintain a dormant state. The predicted protein-protein interactions and the points of disruption provide novel insights that will stimulate advanced hypothesis-driven approaches toward revealing a clearer understanding of new virulence factors and mechanisms influencing the pathogenesis of brucellosis.
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Affiliation(s)
- Carlos A Rossetti
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | | | - Sara D Lawhon
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | - Jairo S Nunes
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | - Tamara Gull
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | - Sangeeta Khare
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
| | - Leslie G Adams
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Science, Texas A&M UniversityCollege Station, TX, United States
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18
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Barbier T, Zúñiga-Ripa A, Moussa S, Plovier H, Sternon JF, Lázaro-Antón L, Conde-Álvarez R, De Bolle X, Iriarte M, Moriyón I, Letesson JJ. Brucella central carbon metabolism: an update. Crit Rev Microbiol 2017; 44:182-211. [PMID: 28604247 DOI: 10.1080/1040841x.2017.1332002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The brucellae are facultative intracellular pathogens causing brucellosis, an important zoonosis. Here, we review the nutritional, genetic, proteomic and transcriptomic studies on Brucella carbon uptake and central metabolism, information that is needed for a better understanding of Brucella virulence. There is no uniform picture across species but the studies suggest primary and/or secondary transporters for unknown carbohydrates, lactate, glycerol phosphate, erythritol, xylose, ribose, glucose and glucose/galactose, and routes for their incorporation to central metabolism, including an erythritol pathway feeding the pentose phosphate cycle. Significantly, all brucellae lack phosphoenolpyruvate synthase and phosphofructokinase genes, which confirms previous evidence on glycolysis absence, but carry all Entner-Doudoroff (ED) pathway and Krebs cycle (and glyoxylate pathway) genes. However, glucose catabolism proceeds through the pentose phosphate cycle in the classical species, and the ED pathway operates in some rodent-associated brucellae, suggesting an ancestral character for this pathway in this group. Gluconeogenesis is functional but does not rely exclusively on classical fructose bisphosphatases. Evidence obtained using infection models is fragmentary but suggests the combined or sequential use of hexoses/pentoses, amino acids and gluconeogenic substrates. We also discuss the role of the phosphotransferase system, stringent reponse, quorum sensing, BvrR/S and sRNAs in metabolism control, an essential aspect of the life style of facultative intracellular parasites.
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Affiliation(s)
- T Barbier
- a Unité de Recherche en Biologie des Microorganismes , Laboratoire d'Immunologie et de Microbiologie, NARILIS, Université de Namur , Namur , Belgium
| | - A Zúñiga-Ripa
- b Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra (IdISNA) and Depto. Microbiología y Parasitología , Universidad de Navarra, Edificio de Investigación , Pamplona , Spain
| | - S Moussa
- a Unité de Recherche en Biologie des Microorganismes , Laboratoire d'Immunologie et de Microbiologie, NARILIS, Université de Namur , Namur , Belgium
| | - H Plovier
- a Unité de Recherche en Biologie des Microorganismes , Laboratoire d'Immunologie et de Microbiologie, NARILIS, Université de Namur , Namur , Belgium
| | - J F Sternon
- a Unité de Recherche en Biologie des Microorganismes , Laboratoire d'Immunologie et de Microbiologie, NARILIS, Université de Namur , Namur , Belgium
| | - L Lázaro-Antón
- b Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra (IdISNA) and Depto. Microbiología y Parasitología , Universidad de Navarra, Edificio de Investigación , Pamplona , Spain
| | - R Conde-Álvarez
- b Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra (IdISNA) and Depto. Microbiología y Parasitología , Universidad de Navarra, Edificio de Investigación , Pamplona , Spain
| | - X De Bolle
- a Unité de Recherche en Biologie des Microorganismes , Laboratoire d'Immunologie et de Microbiologie, NARILIS, Université de Namur , Namur , Belgium
| | - M Iriarte
- b Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra (IdISNA) and Depto. Microbiología y Parasitología , Universidad de Navarra, Edificio de Investigación , Pamplona , Spain
| | - I Moriyón
- b Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra (IdISNA) and Depto. Microbiología y Parasitología , Universidad de Navarra, Edificio de Investigación , Pamplona , Spain
| | - J J Letesson
- b Instituto de Salud Tropical (ISTUN), Instituto de Investigación Sanitaria de Navarra (IdISNA) and Depto. Microbiología y Parasitología , Universidad de Navarra, Edificio de Investigación , Pamplona , Spain
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19
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Abdou E, Jiménez de Bagüés MP, Martínez-Abadía I, Ouahrani-Bettache S, Pantesco V, Occhialini A, Al Dahouk S, Köhler S, Jubier-Maurin V. RegA Plays a Key Role in Oxygen-Dependent Establishment of Persistence and in Isocitrate Lyase Activity, a Critical Determinant of In vivo Brucella suis Pathogenicity. Front Cell Infect Microbiol 2017; 7:186. [PMID: 28573107 PMCID: PMC5435760 DOI: 10.3389/fcimb.2017.00186] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 04/28/2017] [Indexed: 12/25/2022] Open
Abstract
For aerobic human pathogens, adaptation to hypoxia is a critical factor for the establishment of persistent infections, as oxygen availability is low inside the host. The two-component system RegB/A of Brucella suis plays a central role in the control of respiratory systems adapted to oxygen deficiency, and in persistence in vivo. Using an original "in vitro model of persistence" consisting in gradual oxygen depletion, we compared transcriptomes and proteomes of wild-type and ΔregA strains to identify the RegA-regulon potentially involved in the set-up of persistence. Consecutive to oxygen consumption resulting in growth arrest, 12% of the genes in B. suis were potentially controlled directly or indirectly by RegA, among which numerous transcriptional regulators were up-regulated. In contrast, genes or proteins involved in envelope biogenesis and in cellular division were repressed, suggesting a possible role for RegA in the set-up of a non-proliferative persistence state. Importantly, the greatest number of the RegA-repressed genes and proteins, including aceA encoding the functional IsoCitrate Lyase (ICL), were involved in energy production. A potential consequence of this RegA impact may be the slowing-down of the central metabolism as B. suis progressively enters into persistence. Moreover, ICL is an essential determinant of pathogenesis and long-term interactions with the host, as demonstrated by the strict dependence of B. suis on ICL activity for multiplication and persistence during in vivo infection. RegA regulates gene or protein expression of all functional groups, which is why RegA is a key regulator of B. suis in adaptation to oxygen depletion. This function may contribute to the constraint of bacterial growth, typical of chronic infection. Oxygen-dependent activation of two-component systems that control persistence regulons, shared by several aerobic human pathogens, has not been studied in Brucella sp. before. This work therefore contributes significantly to the unraveling of persistence mechanisms in this important zoonotic pathogen.
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Affiliation(s)
- Elias Abdou
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - María P. Jiménez de Bagüés
- Unidad de Tecnología en Producción y Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria, Instituto Agroalimentario de Aragón (CITA-Universidad de Zaragoza)Zaragoza, Spain
| | - Ignacio Martínez-Abadía
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - Safia Ouahrani-Bettache
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - Véronique Pantesco
- Institut de Médecine Régénératrice et Biothérapie—U1183 Institut National de la Santé et de la Recherche MédicaleMontpellier, France
| | - Alessandra Occhialini
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - Sascha Al Dahouk
- Department of Biological Safety, German Federal Institute for Risk AssessmentBerlin, Germany
| | - Stephan Köhler
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
| | - Véronique Jubier-Maurin
- Institut de Recherche en Infectiologie de Montpellier UMR9004, Centre National de la Recherche Scientifique, Université de MontpellierMontpellier, France
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20
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Genetic Characterization and Comparative Genome Analysis of Brucella melitensis Isolates from India. Int J Genomics 2016; 2016:3034756. [PMID: 27525259 PMCID: PMC4976149 DOI: 10.1155/2016/3034756] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/26/2016] [Accepted: 05/29/2016] [Indexed: 12/31/2022] Open
Abstract
Brucellosis is the most frequent zoonotic disease worldwide, with over 500,000 new human infections every year. Brucella melitensis, the most virulent species in humans, primarily affects goats and the zoonotic transmission occurs by ingestion of unpasteurized milk products or through direct contact with fetal tissues. Brucellosis is endemic in India but no information is available on population structure and genetic diversity of Brucella spp. in India. We performed multilocus sequence typing of four B. melitensis strains isolated from naturally infected goats from India. For more detailed genetic characterization, we carried out whole genome sequencing and comparative genome analysis of one of the B. melitensis isolates, Bm IND1. Genome analysis identified 141 unique SNPs, 78 VNTRs, 51 Indels, and 2 putative prophage integrations in the Bm IND1 genome. Our data may help to develop improved epidemiological typing tools and efficient preventive strategies to control brucellosis.
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21
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Tian M, Qu J, Bao Y, Gao J, Liu J, Wang S, Sun Y, Ding C, Yu S. Construction of pTM series plasmids for gene expression in Brucella species. J Microbiol Methods 2016; 123:18-23. [DOI: 10.1016/j.mimet.2016.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/02/2016] [Accepted: 02/02/2016] [Indexed: 11/25/2022]
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RNA-seq reveals the critical role of CspA in regulating Brucella melitensis metabolism and virulence. SCIENCE CHINA-LIFE SCIENCES 2016; 59:417-24. [PMID: 26740105 DOI: 10.1007/s11427-015-4981-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 11/23/2015] [Indexed: 10/22/2022]
Abstract
Brucella melitensis is a facultative intracellular bacterium that replicates within macrophages. The ability of Brucella to survive and multiply in the hostile environment of host macrophages is essential for its virulence. The cold shock protein CspA plays an important role in the virulence of B. melitensis. To analyze the genes regulated by CspA, the whole transcriptomes of B. melitensis NIΔcspA and its parental wild-type strain, B. melitensis NI, were sequenced and analyzed using the Solexa/Illumina sequencing platform. A total of 446 differentially expressed genes were identified, including 324 up-regulated and 122 down-regulated genes. Numerous genes identified are involved in amino acid, fatty acid, nitrogen, and energy metabolism. Interestingly, all genes involved in the type IV secretion system and LuxR-type regulatory protein VjbR were significantly down-regulated in NIΔcspA. In addition, an effector translocation assay confirmed that the function of T4SS in NIΔcspA is influenced by deletion of the cspA gene. These results revealed the differential phenomena associated with virulence and metabolism in NIΔcspA and NI, providing important information for understanding detailed CspA-regulated interaction networks and Brucella pathogenesis.
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23
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Phosphoenolpyruvate Phosphotransferase System Components Modulate Gene Transcription and Virulence of Borrelia burgdorferi. Infect Immun 2015; 84:754-64. [PMID: 26712207 DOI: 10.1128/iai.00917-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 12/17/2015] [Indexed: 12/16/2022] Open
Abstract
The phosphoenolpyruvate phosphotransferase system (PEP-PTS) and adenylate cyclase (AC) IV (encoded by BB0723 [cyaB]) are well conserved in different species of Borrelia. However, the functional roles of PEP-PTS and AC in the infectious cycle of Borrelia have not been characterized previously. We examined 12 PEP-PTS transporter component mutants by needle inoculation of mice to assess their ability to cause mouse infection. Transposon mutants with mutations in the EIIBC components (ptsG) (BB0645, thought to be involved in glucose-specific transport) were unable to cause infection in mice, while all other tested PEP-PTS mutants retained infectivity. Infectivity was partially restored in an in trans-complemented strain of the ptsG mutant. While the ptsG mutant survived normally in unfed as well as fed ticks, it was unable to cause infection in mice by tick transmission, suggesting that the function of ptsG is essential to establish infection by either needle inoculation or tick transmission. In Gram-negative organisms, the regulatory effects of the PEP-PTS are mediated by adenylate cyclase and cyclic AMP (cAMP) levels. A recombinant protein encoded by B. burgdorferi BB0723 (a putative cyaB homolog) was shown to have adenylate cyclase activity in vitro; however, mutants with mutations in this gene were fully infectious in the tick-mouse infection cycle, indicating that its function is not required in this process. By transcriptome analysis, we demonstrated that the ptsG gene may directly or indirectly modulate gene expression of Borrelia burgdorferi. Overall, the PEP-PTS glucose transporter PtsG appears to play important roles in the pathogenesis of B. burgdorferi that extend beyond its transport functions.
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Sheehan LM, Budnick JA, Blanchard C, Dunman PM, Caswell CC. A LysR-family transcriptional regulator required for virulence in Brucella abortus is highly conserved among the α-proteobacteria. Mol Microbiol 2015; 98:318-28. [PMID: 26175079 DOI: 10.1111/mmi.13123] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2015] [Indexed: 12/31/2022]
Abstract
Small RNAs are principal elements of bacterial gene regulation and physiology. Two small RNAs in Brucella abortus, AbcR1 and AbcR2, are required for wild-type virulence. Examination of the abcR loci revealed the presence of a gene encoding a LysR-type transcriptional regulator flanking abcR2 on chromosome 1. Deletion of this lysR gene (bab1_1517) resulted in the complete loss of abcR2 expression while no difference in abcR1 expression was observed. The B. abortus bab1_1517 mutant strain was significantly attenuated in macrophages and mice, and bab1_1517 was subsequently named vtlR for virulence-associated transcriptional LysR-family regulator. Microarray analysis revealed three additional genes encoding small hypothetical proteins also under the control of VtlR. Electrophoretic mobility shift assays demonstrated that VtlR binds directly to the promoter regions of abcR2 and the three hypothetical protein-encoding genes, and DNase I footprint analysis identified the specific nucleotide sequence in these promoters that VtlR binds to and drives gene expression. Strikingly, orthologs of VtlR are encoded in a wide range of host-associated α-proteobacteria, and it is likely that the VtlR genetic system represents a common regulatory circuit critical for host-bacterium interactions.
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Affiliation(s)
- Lauren M Sheehan
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
| | - James A Budnick
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Catlyn Blanchard
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Paul M Dunman
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Clayton C Caswell
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, VA-MD College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24060, USA
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Lv S, Si W, Yu S, Li Z, Wang X, Chen L, Zhang W, Liu S. Characteristics of invasion-reduced hilA gene mutant of Salmonella Enteritidis in vitro and in vivo. Res Vet Sci 2015; 101:63-8. [PMID: 26267091 DOI: 10.1016/j.rvsc.2015.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 03/30/2015] [Accepted: 05/10/2015] [Indexed: 10/23/2022]
Abstract
Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) is a facultative intracellular pathogen that causes huge losses in poultry industry and also food poisoning in humans due to its being a food-borne pathogen. Functions of Invasion-related genes need to be explored, as invasion is a key step for Salmonella infection. In this study, a transposon mutant library of Salmonella Enteritidis isolate SM6 was constructed and screened for the invasion-related genes via incubation with Caco-2 cells. Three stably attenuated mutants were identified for significantly reduced invasion with insertions all in hilA (hyperinvasive locus A) gene. We constructed and evaluated the hilA deletion mutant in vivo and in vitro. SM6△hilA showed significantly reduced ability to invade Caco-2 cells and decreased pathogenicity in chicks. However, the bacterial load and pathological damage in the cecum were significantly higher than those in the SM6 in vivo. Present results provide new evidences for pathogenicity research on Salmonella Enteritidis.
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Affiliation(s)
- Shuang Lv
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Wei Si
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Shenye Yu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Zhaoli Li
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Xiumei Wang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Liping Chen
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Wanjiang Zhang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China.
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de Figueiredo P, Ficht TA, Rice-Ficht A, Rossetti CA, Adams LG. Pathogenesis and immunobiology of brucellosis: review of Brucella-host interactions. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 185:1505-17. [PMID: 25892682 DOI: 10.1016/j.ajpath.2015.03.003] [Citation(s) in RCA: 271] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 02/10/2015] [Accepted: 03/02/2015] [Indexed: 01/18/2023]
Abstract
This review of Brucella-host interactions and immunobiology discusses recent discoveries as the basis for pathogenesis-informed rationales to prevent or treat brucellosis. Brucella spp., as animal pathogens, cause human brucellosis, a zoonosis that results in worldwide economic losses, human morbidity, and poverty. Although Brucella spp. infect humans as an incidental host, 500,000 new human infections occur annually, and no patient-friendly treatments or approved human vaccines are reported. Brucellae display strong tissue tropism for lymphoreticular and reproductive systems with an intracellular lifestyle that limits exposure to innate and adaptive immune responses, sequesters the organism from the effects of antibiotics, and drives clinical disease manifestations and pathology. Stealthy brucellae exploit strategies to establish infection, including i) evasion of intracellular destruction by restricting fusion of type IV secretion system-dependent Brucella-containing vacuoles with lysosomal compartments, ii) inhibition of apoptosis of infected mononuclear cells, and iii) prevention of dendritic cell maturation, antigen presentation, and activation of naive T cells, pathogenesis lessons that may be informative for other intracellular pathogens. Data sets of next-generation sequences of Brucella and host time-series global expression fused with proteomics and metabolomics data from in vitro and in vivo experiments now inform interactive cellular pathways and gene regulatory networks enabling full-scale systems biology analysis. The newly identified effector proteins of Brucella may represent targets for improved, safer brucellosis vaccines and therapeutics.
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Affiliation(s)
- Paul de Figueiredo
- Department of Veterinary Pathobiology, Texas A&M University and Texas AgriLife Research, College Station, Texas; Norman Borlaug Center, Texas A&M University, College Station, Texas; Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas
| | - Thomas A Ficht
- Department of Veterinary Pathobiology, Texas A&M University and Texas AgriLife Research, College Station, Texas
| | - Allison Rice-Ficht
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, Bryan, Texas
| | - Carlos A Rossetti
- Institute of Pathobiology, CICVyA-CNIA, National Institute of Animal Agriculture Technology (INTA), Buenos Aires, Argentina
| | - L Garry Adams
- Department of Veterinary Pathobiology, Texas A&M University and Texas AgriLife Research, College Station, Texas.
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diCenzo GC, Finan TM. Genetic redundancy is prevalent within the 6.7 Mb Sinorhizobium meliloti genome. Mol Genet Genomics 2015; 290:1345-56. [PMID: 25638282 DOI: 10.1007/s00438-015-0998-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/17/2015] [Indexed: 01/09/2023]
Abstract
Biological pathways are frequently identified via a genetic loss-of-function approach. While this approach has proven to be powerful, it is imperfect as illustrated by well-studied pathways continuing to have missing steps. One potential limiting factor is the masking of phenotypes through genetic redundancy. The prevalence of genetic redundancy in bacterial species has received little attention, although isolated examples of functionally redundant gene pairs exist. Here, we made use of a strain of Sinorhizobium meliloti whose genome was reduced by 45 % through the complete removal of a megaplasmid and a chromid (3 Mb of the 6.7 Mb genome was removed) to begin quantifying the level of genetic redundancy within a large bacterial genome. A mutagenesis of the strain with the reduced genome identified a set of transposon insertions precluding growth of this strain on minimal medium. Transfer of these mutations to the wild-type background revealed that 10-15 % of these chromosomal mutations were located within duplicated genes, as they did not prevent growth of cells with the full genome. The functionally redundant genes were involved in a variety of metabolic pathways, including central carbon metabolism, transport, and amino acid biosynthesis. These results indicate that genetic redundancy may be prevalent within large bacterial genomes. Failing to account for redundantly encoded functions in loss-of-function studies will impair our understanding of a broad range of biological processes and limit our ability to use synthetic biology in the construction of designer cell factories.
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Affiliation(s)
- George C diCenzo
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON, L8S 4K1, Canada
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Ronneau S, Moussa S, Barbier T, Conde-Álvarez R, Zuniga-Ripa A, Moriyon I, Letesson JJ. Brucella, nitrogen and virulence. Crit Rev Microbiol 2014; 42:507-25. [PMID: 25471320 DOI: 10.3109/1040841x.2014.962480] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The brucellae are α-Proteobacteria causing brucellosis, an important zoonosis. Although multiplying in endoplasmic reticulum-derived vacuoles, they cause no cell death, suggesting subtle but efficient use of host resources. Brucellae are amino-acid prototrophs able to grow with ammonium or use glutamate as the sole carbon-nitrogen source in vitro. They contain more than twice amino acid/peptide/polyamine uptake genes than the amino-acid auxotroph Legionella pneumophila, which multiplies in a similar vacuole, suggesting a different nutritional strategy. During these two last decades, many mutants of key actors in nitrogen metabolism (transporters, enzymes, regulators, etc.) have been described to be essential for full virulence of brucellae. Here, we review the genomic and experimental data on Brucella nitrogen metabolism and its connection with virulence. An analysis of various aspects of this metabolism (transport, assimilation, biosynthesis, catabolism, respiration and regulation) has highlighted differences and similarities in nitrogen metabolism with other α-Proteobacteria. Together, these data suggest that, during their intracellular life cycle, the brucellae use various nitrogen sources for biosynthesis, catabolism and respiration following a strategy that requires prototrophy and a tight regulation of nitrogen use.
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Affiliation(s)
| | - Simon Moussa
- a UNamur, URBM 61 rue de Bruxelles , Namur , Belgium and
| | | | - Raquel Conde-Álvarez
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
| | - Amaia Zuniga-Ripa
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
| | - Ignacio Moriyon
- b Departamento de Microbiología , Edificio de Investigación, Universidad de Navarra , Pamplona , Spain
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Brambila-Tapia AJL, Armenta-Medina D, Rivera-Gomez N, Perez-Rueda E. Main functions and taxonomic distribution of virulence genes in Brucella melitensis 16 M. PLoS One 2014; 9:e100349. [PMID: 24964015 PMCID: PMC4070974 DOI: 10.1371/journal.pone.0100349] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/24/2014] [Indexed: 11/19/2022] Open
Abstract
Many virulence genes have been detected in attenuated mutants of Brucella melitensis 16 M; nevertheless, a complete report of these genes, including the main Cluster of Orthologous Groups (COG) represented as well as the taxonomical distribution among all complete bacterial and archaeal genomes, has not been analyzed. In this work a total of 160 virulence genes that have been reported in attenuated mutants in B. melitensis were included and analyzed. Additionally, we obtained 250 B. melitensis randomly selected genes as a reference group for the taxonomical comparisons. The COGs and the taxonomical distribution profile for 789 nonredundant bacterial and archaeal genomes were obtained and compared with the whole-genome COG distribution and with the 250 randomly selected genes, respectively. The main COGs associated with virulence genes corresponded to the following: intracellular trafficking, secretion and vesicular transport (U); cell motility (N); nucleotide transport and metabolism (F); transcription (K); and cell wall/membrane/envelope biogenesis (M). In addition, we found that virulence genes presented a higher proportion of orthologs in the Euryarchaeota and Proteobacteria phyla, with a significant decrease in Chlamydiae, Bacteroidetes, Tenericutes, Firmicutes and Thermotogae. In conclusion, we found that genes related to specific functions are more relevant to B. melitensis virulence, with the COG U the most significant. Additionally, the taxonomical distribution of virulence genes highlights the importance of these genes in the related Proteobacteria, being less relevant in distant groups of organisms with the exception of Euryarchaeota.
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Affiliation(s)
- Aniel Jessica Leticia Brambila-Tapia
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- * E-mail: (AJLBT); (EPR)
| | - Dagoberto Armenta-Medina
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Nancy Rivera-Gomez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Ernesto Perez-Rueda
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- * E-mail: (AJLBT); (EPR)
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Brucella abortus depends on pyruvate phosphate dikinase and malic enzyme but not on Fbp and GlpX fructose-1,6-bisphosphatases for full virulence in laboratory models. J Bacteriol 2014; 196:3045-57. [PMID: 24936050 DOI: 10.1128/jb.01663-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The brucellae are the etiological agents of brucellosis, a worldwide-distributed zoonosis. These bacteria are facultative intracellular parasites and thus are able to adjust their metabolism to the extra- and intracellular environments encountered during an infectious cycle. However, this aspect of Brucella biology is imperfectly understood, and the nutrients available in the intracellular niche are unknown. Here, we investigated the central pathways of C metabolism used by Brucella abortus by deleting the putative fructose-1,6-bisphosphatase (fbp and glpX), phosphoenolpyruvate carboxykinase (pckA), pyruvate phosphate dikinase (ppdK), and malic enzyme (mae) genes. In gluconeogenic but not in rich media, growth of ΔppdK and Δmae mutants was severely impaired and growth of the double Δfbp-ΔglpX mutant was reduced. In macrophages, only the ΔppdK and Δmae mutants showed reduced multiplication, and studies with the ΔppdK mutant confirmed that it reached the replicative niche. Similarly, only the ΔppdK and Δmae mutants were attenuated in mice, the former being cleared by week 10 and the latter persisting longer than 12 weeks. We also investigated the glyoxylate cycle. Although aceA (isocitrate lyase) promoter activity was enhanced in rich medium, aceA disruption had no effect in vitro or on multiplication in macrophages or mouse spleens. The results suggest that B. abortus grows intracellularly using a limited supply of 6-C (and 5-C) sugars that is compensated by glutamate and possibly other amino acids entering the Krebs cycle without a critical role of the glyoxylate shunt.
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Wang Z, Wang S, Wu Q. Cold shock protein A plays an important role in the stress adaptation and virulence of Brucella melitensis. FEMS Microbiol Lett 2014; 354:27-36. [PMID: 24661136 DOI: 10.1111/1574-6968.12430] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 03/07/2014] [Accepted: 03/07/2014] [Indexed: 11/29/2022] Open
Abstract
Brucella melitensis is a facultative intracellular pathogen that mainly resides within macrophages. The mechanisms employed by Brucella to adapt to harsh intracellular environments and survive within host macrophages are not clearly understood. Here, we constructed a cspA gene deletion mutant, NIΔcspA, that did not exhibit any discernible growth defect at a normal culture temperature (37 °C) or at a low temperature (15 °C). However, expression of the cspA gene in Brucella was induced by cold, acidic, and oxidative conditions, as determined via quantitative reverse transcription PCR. Unlike its parental strain, B. melitensis NI, the NIΔcspA mutant showed an increased sensitivity to acidic and H2 O2 stresses, especially during the mid-log-phase, and these stress conditions would presumably be encountered by bacteria during intracellular infections. Moreover, macrophage and mouse infection assays indicated that the NIΔcspA mutant fails to replicate in cultured J774.A1 murine macrophages and is rapidly cleared from the spleens of experimentally infected BALB/c mice. These findings suggest that the Brucella cspA gene makes an essential contribution to virulence in vitro and in vivo, most likely by allowing brucellae to adapt appropriately to the harsh environmental conditions encountered within host macrophages.
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Affiliation(s)
- Zhen Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China; Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
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Pandey A, Ding SL, Ficht TA, de Figueiredo P. SiRNA screens using Drosophila cells to identify host factors required for infection. Methods Mol Biol 2014; 1197:229-44. [PMID: 25172284 DOI: 10.1007/978-1-4939-1261-2_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Drosophila melanogaster offers a powerful model system for interrogating interactions between host cells and human bacterial pathogens. Brucella, a gram-negative, facultative intracellular bacterium is the causative agent of brucellosis, a zoonotic disease of global consequence. Over the past several decades, pathogen factors that mediate Brucella infection have been identified. However, host factors that mediate infection have remained obscure. We have used the power of the Drosophila S2 cell system to identify and characterize host factors that support infection by Brucella melitensis. Host protein inositol-requiring enzyme 1 (IRE1α), a transmembrane kinase and master regulator of the eukaryotic unfolded protein response, was shown to play an important role in regulating Brucella infection, thereby providing the first glimpse of host mechanisms that are subverted by the pathogen to support its intracellular lifestyle. Furthermore, our study also established the Drosophila S2 cell as a powerful system for elucidating Brucella host factors. Here, we describe a protocol for using the Drosophila S2 cell system for studying the Brucella-host interaction.
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Affiliation(s)
- Aseem Pandey
- Department of Veterinary Pathobiology, Texas A&M University, 4474 TAMU, College Station, TX, 77843, USA,
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Al Dahouk S, Jubier-Maurin V, Neubauer H, Köhler S. Quantitative analysis of the Brucella suis proteome reveals metabolic adaptation to long-term nutrient starvation. BMC Microbiol 2013; 13:199. [PMID: 24007556 PMCID: PMC3844638 DOI: 10.1186/1471-2180-13-199] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 09/02/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND During the infection process, bacteria are confronted with various stress factors including nutrient starvation. In an in vitro model, adaptation strategies of nutrient-starved brucellae, which are facultative intracellular pathogens capable of long-term persistence, were determined. RESULTS Long-term nutrient starvation in a medium devoid of carbon and nitrogen sources resulted in a rapid decline in viability of Brucella suis during the first three weeks, followed by stabilization of the number of viable bacteria for a period of at least three weeks thereafter. A 2D-Difference Gel Electrophoresis (DIGE) approach allowed the characterization of the bacterial proteome under these conditions. A total of 30 proteins showing altered concentrations in comparison with bacteria grown to early stationary phase in rich medium were identified. More than half of the 27 significantly regulated proteins were involved in bacterial metabolism with a marked reduction of the concentrations of enzymes participating in amino acid and nucleic acid biosynthesis. A total of 70% of the significantly regulated proteins showed an increased expression, including proteins involved in the adaptation to harsh conditions, in regulation, and in transport. CONCLUSIONS The adaptive response of Brucella suis most likely contributes to the long-term survival of the pathogen under starvation conditions, and may play a key role in persistence.
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Affiliation(s)
- Sascha Al Dahouk
- Federal Institute for Risk Assessment, Diedersdorfer Weg 1, D-12277, Berlin Germany.
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Dong H, Liu W, Peng X, Jing Z, Wu Q. The effects of MucR on expression of type IV secretion system, quorum sensing system and stress responses in Brucella melitensis. Vet Microbiol 2013; 166:535-42. [PMID: 23932078 DOI: 10.1016/j.vetmic.2013.06.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 06/24/2013] [Accepted: 06/25/2013] [Indexed: 01/21/2023]
Abstract
MucR is a transcriptional regulator in many bacterial pathogens and is required for virulence in mice and macrophages, resistance to stress responses, and modification of the cell envelope in Brucella spp. To determine why the mucR deleted mutant is attenuated in vivo and in vitro, we performed RNA-seq analysis using Brucella melitensis RNA obtained from B. melitensis 16M and 16MΔmucR grown under the same conditions. We found 442 differentially expressed genes; 310 were over expressed, and 132 were less expressed in 16MΔmucR. Many genes identified are involved in metabolism, cell wall/envelope biogenesis, replication, and translation. Notably, genes involved in type IV secretion system and quorum sensing system were down-regulated in 16MΔmucR. In addition, genes involved in tolerance to acid and iron-limitation were also affected and experimentally verified in this study. The effects of MucR on Brucella survival and persistence in mice and macrophages were related to type IV secretion system, quorum sensing system, and stress tolerance, which also provide added insight to the MucR regulon.
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Affiliation(s)
- Hao Dong
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, PR China
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Global Rsh-dependent transcription profile of Brucella suis during stringent response unravels adaptation to nutrient starvation and cross-talk with other stress responses. BMC Genomics 2013; 14:459. [PMID: 23834488 PMCID: PMC3710219 DOI: 10.1186/1471-2164-14-459] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 06/18/2013] [Indexed: 01/08/2023] Open
Abstract
Background In the intracellular pathogen Brucella spp., the activation of the stringent response, a global regulatory network providing rapid adaptation to growth-affecting stress conditions such as nutrient deficiency, is essential for replication in the host. A single, bi-functional enzyme Rsh catalyzes synthesis and hydrolysis of the alarmone (p)ppGpp, responsible for differential gene expression under stringent conditions. Results cDNA microarray analysis allowed characterization of the transcriptional profiles of the B. suis 1330 wild-type and Δrsh mutant in a minimal medium, partially mimicking the nutrient-poor intramacrophagic environment. A total of 379 genes (11.6% of the genome) were differentially expressed in a rsh-dependent manner, of which 198 were up-, and 181 were down-regulated. The pleiotropic character of the response was confirmed, as the genes encoded an important number of transcriptional regulators, cell envelope proteins, stress factors, transport systems, and energy metabolism proteins. Virulence genes such as narG and sodC, respectively encoding respiratory nitrate reductase and superoxide dismutase, were under the positive control of (p)ppGpp, as well as expression of the cbb3-type cytochrome c oxidase, essential for chronic murine infection. Methionine was the only amino acid whose biosynthesis was absolutely dependent on stringent response in B. suis. Conclusions The study illustrated the complexity of the processes involved in adaptation to nutrient starvation, and contributed to a better understanding of the correlation between stringent response and Brucella virulence. Most interestingly, it clearly indicated (p)ppGpp-dependent cross-talk between at least three stress responses playing a central role in Brucella adaptation to the host: nutrient, oxidative, and low-oxygen stress.
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Comparison of genomes of Brucella melitensis M28 and the B. melitensis M5-90 derivative vaccine strain highlights the translation elongation factor Tu gene tuf2 as an attenuation-related gene. Infect Immun 2013; 81:2812-8. [PMID: 23716607 DOI: 10.1128/iai.00224-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Brucella melitensis causes brucellosis, a disease affecting sheep, cattle, and sometimes humans. Attenuated B. melitensis strain M5-90, derived from virulent strain M28, is widely used as a live vaccine in ruminants in China. Genetic differences between the strains may cast light on the mechanism of attenuation. We recently reported the complete genomic sequences of M28 and M5-90. Genome organization is highly conserved between these isolates, and also with virulent strains 16 M and ATCC 23457. Analysis revealed 23 open reading frames (ORFs) with consistent differences between M5-90 and the virulent strains. Notably, the tuf2 gene encoding translation elongation factor EF-Tu from M5-90 contained 50 single nucleotide polymorphisms (SNPs) and 9 gaps (indels) compared to tuf2 of M28 or of the other virulent strains. There were no changes in tuf1. To evaluate the potential role of EF-Tu in pathogenesis, tuf1 and tuf2 mutants of M28 and an M5-90 strain harboring wild-type tuf2 were constructed, and their virulence/attenuation was evaluated in vivo. We report that the tuf2 gene plays an important role in the attenuation of M5-90 virulence.
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Gomez G, Adams LG, Rice-Ficht A, Ficht TA. Host-Brucella interactions and the Brucella genome as tools for subunit antigen discovery and immunization against brucellosis. Front Cell Infect Microbiol 2013; 3:17. [PMID: 23720712 PMCID: PMC3655278 DOI: 10.3389/fcimb.2013.00017] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 04/26/2013] [Indexed: 01/18/2023] Open
Abstract
Vaccination is the most important approach to counteract infectious diseases. Thus, the development of new and improved vaccines for existing, emerging, and re-emerging diseases is an area of great interest to the scientific community and general public. Traditional approaches to subunit antigen discovery and vaccine development lack consideration for the critical aspects of public safety and activation of relevant protective host immunity. The availability of genomic sequences for pathogenic Brucella spp. and their hosts have led to development of systems-wide analytical tools that have provided a better understanding of host and pathogen physiology while also beginning to unravel the intricacies at the host-pathogen interface. Advances in pathogen biology, host immunology, and host-agent interactions have the potential to serve as a platform for the design and implementation of better-targeted antigen discovery approaches. With emphasis on Brucella spp., we probe the biological aspects of host and pathogen that merit consideration in the targeted design of subunit antigen discovery and vaccine development.
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Affiliation(s)
- Gabriel Gomez
- Department of Veterinary Pathobiology, Texas A&M University College Station, TX 77843, USA.
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Gomez G, Pei J, Mwangi W, Adams LG, Rice-Ficht A, Ficht TA. Immunogenic and invasive properties of Brucella melitensis 16M outer membrane protein vaccine candidates identified via a reverse vaccinology approach. PLoS One 2013; 8:e59751. [PMID: 23533646 PMCID: PMC3606113 DOI: 10.1371/journal.pone.0059751] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 02/18/2013] [Indexed: 01/18/2023] Open
Abstract
Brucella is the etiologic agent of brucellosis, one of the most common and widely distributed zoonotic diseases. Its highly infectious nature, the insidious, systemic, chronic, debilitating aspects of the disease and the lack of an approved vaccine for human use in the United States are features that make Brucella a viable threat to public health. One of the main impediments to vaccine development is identification of suitable antigens. In order to identify antigens that could potentially be used in a vaccine formulation, we describe a multi-step antigen selection approach. We initially used an algorithm (Vaxign) to predict ORF encoding outer membrane proteins with antigenic determinants. Differential gene expression during acute infection and published evidence for a role in virulence were used as criteria for down-selection of the candidate antigens that resulted from in silico prediction. This approach resulted in the identification of nine Brucella melitensis outer membrane proteins, 5 of which were recombinantly expressed and used for validation. Omp22 and Hia had the highest in silico scores for adhesin probability and also conferred invasive capacity to E. coli overexpressing recombinant proteins. With the exception of FlgK in the goat, all proteins reacted to pooled sera from exposed goats, mice, and humans. BtuB, Hia and FlgK stimulated a mixed Th1-Th2 response in splenocytes from immunized mice while BtuB and Hia elicited NO release from splenocytes of S19 immunized mice. The results support the applicability of the current approach to the identification of antigens with immunogenic and invasive properties. Studies to assess immunogenicity and protective efficacy of individual proteins in the mouse are currently underway.
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Affiliation(s)
- Gabriel Gomez
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America.
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Diverse genetic regulon of the virulence-associated transcriptional regulator MucR in Brucella abortus 2308. Infect Immun 2013; 81:1040-51. [PMID: 23319565 DOI: 10.1128/iai.01097-12] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Ros-type regulator MucR is one of the few transcriptional regulators that have been linked to virulence in Brucella. Here, we show that a Brucella abortus in-frame mucR deletion strain exhibits a pronounced growth defect during in vitro cultivation and, more importantly, that the mucR mutant is attenuated in cultured macrophages and in mice. The genetic basis for the attenuation of Brucella mucR mutants has not been defined previously, but in the present study the genes regulated by MucR in B. abortus have been elucidated using microarray analysis and real-time reverse transcription-PCR (RT-PCR). In B. abortus 2308, MucR regulates a wide variety of genes whose products may function in establishing and maintaining cell envelope integrity, polysaccharide biosynthesis, iron homeostasis, genome plasticity, and transcriptional regulation. Particularly notable among the MucR-regulated genes identified is arsR6 (nolR), which encodes a transcriptional regulator previously linked to virulence in Brucella melitensis 16 M. Importantly, electrophoretic mobility shift assays (EMSAs) determined that a recombinant MucR protein binds directly to the promoter regions of several genes repressed by MucR (including arsR6 [nolR]), and in Brucella, as in other alphaproteobacteria, MucR binds to its own promoter to repress expression of the gene that encodes it. Overall, these studies have uncovered the diverse genetic regulon of MucR in Brucella, and in doing so this work has begun to define the MucR-controlled genetic circuitry whose misregulation contributes to the virulence defect of Brucella mucR mutants.
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Brucella melitensis MucR, an orthologue of Sinorhizobium meliloti MucR, is involved in resistance to oxidative, detergent, and saline stresses and cell envelope modifications. J Bacteriol 2012; 195:453-65. [PMID: 23161025 DOI: 10.1128/jb.01336-12] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella spp. and Sinorhizobium meliloti are alphaproteobacteria that share not only an intracellular lifestyle in their respective hosts, but also a crucial requirement for cell envelope components and their timely regulation for a successful infectious cycle. Here, we report the characterization of Brucella melitensis mucR, which encodes a zinc finger transcriptional regulator that has previously been shown to be involved in cellular and mouse infections at early time points. MucR modulates the surface properties of the bacteria and their resistance to environmental stresses (i.e., oxidative stress, cationic peptide, and detergents). We show that B. melitensis mucR is a functional orthologue of S. meliloti mucR, because it was able to restore the production of succinoglycan in an S. meliloti mucR mutant, as detected by calcofluor staining. Similar to S. meliloti MucR, B. melitensis MucR also represses its own transcription and flagellar gene expression via the flagellar master regulator ftcR. More surprisingly, we demonstrate that MucR regulates a lipid A core modification in B. melitensis. These changes could account for the attenuated virulence of a mucR mutant. These data reinforce the idea that there is a common conserved circuitry between plant symbionts and animal pathogens that regulates the relationship they have with their hosts.
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Mirabella A, Yañez Villanueva RM, Delrue RM, Uzureau S, Zygmunt MS, Cloeckaert A, De Bolle X, Letesson JJ. The two-component system PrlS/PrlR of Brucella melitensis is required for persistence in mice and appears to respond to ionic strength. MICROBIOLOGY-SGM 2012; 158:2642-2651. [PMID: 22859617 DOI: 10.1099/mic.0.060863-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacterial adaptation to environmental conditions is essential to ensure maximal fitness in the face of several stresses. In this context, two-component systems (TCSs) represent a predominant signal transduction mechanism, allowing an appropriate response to be mounted when a stimulus is sensed. As facultative intracellular pathogens, Brucella spp. face various environmental conditions, and an adequate response is required for a successful infection process. Recently, bioinformatic analysis of Brucella genomes predicted a set of 15 bona fide TCS pairs, among which some have been previously investigated. In this report, we characterized a new TCS locus called prlS/R, for probable proline sensor-regulator. It encodes a hybrid histidine kinase (PrlS) with an unusual Na(+)/solute symporter N-terminal domain and a transcriptional regulator (belonging to the LuxR family) (PrlR). In vitro, Brucella spp. with a functional PrlR/S system form bacterial aggregates, which seems to be an adaptive response to a hypersaline environment, while a prlS/R mutant does not. We identified ionic strength as a possible signal sensed by this TCS. Finally, this work correlates the absence of a functional PrlR/S system with the lack of hypersaline-induced aggregation in particular marine Brucella spp.
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Affiliation(s)
- Aurélie Mirabella
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Rosse-Mary Yañez Villanueva
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Rose-May Delrue
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Sophie Uzureau
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Michel S Zygmunt
- Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, F-37000 Tours, France.,INRA, UMR1282 Infectiologie et Santé Publique, F-37380 Nouzilly, France
| | - Axel Cloeckaert
- Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, F-37000 Tours, France.,INRA, UMR1282 Infectiologie et Santé Publique, F-37380 Nouzilly, France
| | - Xavier De Bolle
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
| | - Jean-Jacques Letesson
- Unité de Recherche en Biologie des Microorganismes (URBM), NARILIS, University of Namur (FUNDP), 61 rue de Bruxelles, B-5000 Namur, Belgium
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Sun YH, de Jong MF, den Hartigh AB, Roux CM, Rolán HG, Tsolis RM. The small protein CydX is required for function of cytochrome bd oxidase in Brucella abortus. Front Cell Infect Microbiol 2012; 2:47. [PMID: 22919638 PMCID: PMC3417669 DOI: 10.3389/fcimb.2012.00047] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 03/17/2012] [Indexed: 01/01/2023] Open
Abstract
A large number of hypothetical genes potentially encoding small proteins of unknown function are annotated in the Brucella abortus genome. Individual deletion of 30 of these genes identified four mutants, in BAB1_0355, BAB2_0726, BAB2_0470, and BAB2_0450 that were highly attenuated for infection. BAB2_0726, an YbgT-family protein located at the 3′ end of the cydAB genes encoding cytochrome bd ubiquinal oxidase, was designated cydX. A B. abortus cydX mutant lacked cytochrome bd oxidase activity, as shown by increased sensitivity to H2O2, decreased acid tolerance and increased resistance to killing by respiratory inhibitors. The C terminus, but not the N terminus, of CydX was located in the periplasm, suggesting that CydX is an integral cytoplasmic membrane protein. Phenotypic analysis of the cydX mutant, therefore, suggested that CydX is required for full function of cytochrome bd oxidase, possibly via regulation of its assembly or activity.
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Affiliation(s)
- Yao-Hui Sun
- Department of Medical Microbiology and Immunology, University of California at Davis, Davis CA, USA
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43
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Abstract
Brucellosis is a global disease of domestic and wild mammals that is caused by intracellular bacteria of the genus Brucella. Although humans are not a natural reservoir for Brucella, infection in the human population is common in many countries, and brucellosis is one of the most common zoonotic infections. Brucella species have evolved to avoid the host's immune system and infection is usually characterized by long-term persistence of the bacteria. One important Brucella virulence factor for intracellular survival and persistence in the host is the type IV secretion system. This review will discuss the Brucella type IV secretion system in detail, including current knowledge of architecture and regulation, as well as the newly identified effector substrates that this system transports into host cells.
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Affiliation(s)
- Maarten F de Jong
- Department of Medical Microbiology & Immunology, University of California, Davis, CA, USA
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von Bargen K, Gorvel JP, Salcedo SP. Internal affairs: investigating the Brucella intracellular lifestyle. FEMS Microbiol Rev 2012; 36:533-62. [PMID: 22373010 DOI: 10.1111/j.1574-6976.2012.00334.x] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 01/10/2012] [Accepted: 02/16/2012] [Indexed: 01/18/2023] Open
Abstract
Bacteria of the genus Brucella are Gram-negative pathogens of several animal species that cause a zoonotic disease in humans known as brucellosis or Malta fever. Within their hosts, brucellae reside within different cell types where they establish a replicative niche and remain protected from the immune response. The aim of this article is to discuss recent advances in the field in the specific context of the Brucella intracellular 'lifestyle'. We initially discuss the different host cell targets and their relevance during infection. As it represents the key to intracellular replication, the focus is then set on the maturation of the Brucella phagosome, with particular emphasis on the Brucella factors that are directly implicated in intracellular trafficking and modulation of host cell signalling pathways. Recent data on the role of the type IV secretion system are discussed, novel effector molecules identified and how some of them impact on trafficking events. Current knowledge on Brucella gene regulation and control of host cell death are summarized, as they directly affect intracellular persistence. Understanding how Brucella molecules interplay with their host cell targets to modulate cellular functions and establish the intracellular niche will help unravel how this pathogen causes disease.
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Affiliation(s)
- Kristine von Bargen
- Faculté de Sciences de Luminy, Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, UM 2, Marseille Cedex, France
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Deep sequencing-based expression transcriptional profiling changes during Brucella infection. Microb Pathog 2012; 52:267-77. [PMID: 22342430 DOI: 10.1016/j.micpath.2012.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Revised: 01/27/2012] [Accepted: 02/02/2012] [Indexed: 01/18/2023]
Abstract
Brucellosis is a worldwide zoonotic infectious disease that has significant economic effects on animal production and human health. The host macrophage -Brucella interaction is critical to the establishment of infections. Thus, the kinetic transcriptional profile of gene expression in macrophages infected with the Brucella melitensis strain 16M was investigated in the current study using a technology based on deep sequencing. The total RNA was extracted from macrophages 0, 4, and 24 h post-infection. Data analysis showed that in the gene ontology term, the expression of genes in the endoplasmic reticulum, lysosomes, as well as those involved in programmed cell death and apoptosis significantly changed during the first 24 h post-infection. Pathway enrichment analysis indicated that the genes in the apoptosis pathway, NOD-like receptor signaling pathway, Fc gamma R-mediated phagocytosis, lysosome pathway, p53 signaling pathway, and protein processing in the endoplasmic reticulum significantly changed during the first 24 h post-infection. The B-cell receptor and toll-like receptor signaling pathways were also significantly changed 24 h post-infection compared with those 4 h post-infection. The results of the current study can contribute to an improved understanding of the manner by which host cell responses may be manipulated to prevent Brucella infection.
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Barbier T, Nicolas C, Letesson JJ. Brucella adaptation and survival at the crossroad of metabolism and virulence. FEBS Lett 2011; 585:2929-34. [PMID: 21864534 DOI: 10.1016/j.febslet.2011.08.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 08/05/2011] [Accepted: 08/05/2011] [Indexed: 12/28/2022]
Abstract
"In vivo" bacterial nutrition, i.e. the nature of the metabolic network and substrate(s) used by bacteria within their host, is a fundamental aspect of pathogenic or symbiotic lifestyles. A typical example are the Brucella spp., facultative intracellular pathogens responsible for chronic infections of animals and humans. Their virulence relies on their ability to modulate immune response and the physiology of host cells, but the fine-tuning of their metabolism in the host during infection appears increasingly crucial. Here we review new insights on the links between Brucella virulence and metabolism, pointing out the need to investigate both aspects to decipher Brucella infectious strategies.
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Affiliation(s)
- T Barbier
- Research Unit in Molecular Biology (URBM), NARILIS, University of Namur, Namur, Belgium
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47
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Pei J, Ficht TA. Lipopolysaccharide: a complex role in the pathogenesis of brucellosis. Vet J 2011; 189:5-6. [PMID: 20702124 DOI: 10.1016/j.tvjl.2010.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 07/07/2010] [Accepted: 07/08/2010] [Indexed: 11/24/2022]
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Protective efficacy and safety of Brucella melitensis 16MΔmucR against intraperitoneal and aerosol challenge in BALB/c mice. Infect Immun 2011; 79:3653-8. [PMID: 21708998 DOI: 10.1128/iai.05330-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Brucellosis is a zoonosis of nearly worldwide distribution. Vaccination against this pathogen is an important control strategy to prevent the disease. Currently licensed vaccine strains used in animals are unacceptable for human use due to undesirable side effects and modest protection. Substantial progress has been made during the past 10 years toward the development of improved vaccines for brucellosis. In part, this has been achieved by the identification and characterization of live attenuated mutants that are safer in the host but still can stimulate an adequate immune response. In the present study, the identification and characterization of the mucR mutant (BMEI 1364) as a vaccine candidate for brucellosis was conducted. BALB/c mice were vaccinated intraperitoneally at a dose of 10(5) CFU with the mutant to evaluate safety and protective efficacy against intraperitoneal and aerosol challenge. All animals vaccinated with the vaccine candidate demonstrated a statistically significant degree of protection against both intraperitoneal and aerosol challenge. Safety was revealed by the absence of Brucella associated pathological changes, including splenomegaly, hepatomegaly, or granulomatous disease. These results suggest that the 16MΔmucR vaccine is safe, elicits a strong protective immunity, and should be considered as a promising vaccine candidate for human use.
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Turse JE, Pei J, Ficht TA. Lipopolysaccharide-Deficient Brucella Variants Arise Spontaneously during Infection. Front Microbiol 2011; 2:54. [PMID: 21833310 PMCID: PMC3153030 DOI: 10.3389/fmicb.2011.00054] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 02/10/2011] [Indexed: 12/22/2022] Open
Abstract
Lipopolysaccharide-deficient mutants of smooth Brucella species (rough mutants) have been shown to arise spontaneously in culture. However, in situ analysis of Brucella infected macrophages using antibody directed against O-polysaccharide suggested a loss of reactivity of Brucella consistent with the appearance of rough organisms, and a potential contribution to infection. The experiments reported describe the direct recovery of Brucella from macrophages infected in vitro and from the spleens of infected mice at a frequency similar to that described in vitro, suggesting that Brucella dissociation is not simply an in vitro artifact. The frequency of appearance of spontaneous rough organisms deficient in O-polysaccharide expression measured in vitro is approximately 2–3 logs higher than the appearance of mutation to antibiotic resistance, purine auxotrophy, or reversion of erythritol sensitive ΔeryC mutants to tolerance. Genetic trans-complementation using a plasmid-based expression of Brucella manBA successfully restored O-polysaccharide expression in only one-third of O-polysaccharide deficient spontaneous mutants. Suggesting that the appearance of rough mutants is caused by mutation at more than one locus. In addition, Sanger sequencing of the manBA structural genes detected multiple sequence changes that may explain the observed phenotypic differences. The presence of O-polysaccharide resulted in macrophage and neutrophil infiltration into the peritoneal cavity and systemic distribution of the organism. In contrast, rough organisms are controlled by resident macrophages or by extracellular killing mechanisms and rapidly cleared from this compartment consistent with the inability to cause disease. Loss of O-polysaccharide expression appears to be stochastic giving rise to organisms with biological properties distinct from the parental smooth organism during the course of infection.
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Affiliation(s)
- Joshua E Turse
- Veterinary Pathobiology and Faculty of Genetics, Texas A&M University and Texas AgriLife Research College Station, TX, USA
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50
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Abstract
Three major techniques have been employed for broad-range in vitro mutagenesis of Brucella species. Shotgun approaches capable of generating large libraries of randomly inserted transposon mutants include Tn5, mariner (Himar1), and mini-Tn5 signature-tagged mutagenesis. Allelic exchange has also been extensively employed for targeted gene deletion. In general, plasmid and transposon delivery into Brucella has relied upon electroporation; however, conjugation has also been successfully employed. Both approaches have been used to identify critical virulence determinants necessary for disease and intracellular survival of the organism. Perhaps more importantly these approaches have provided an opportunity to develop attenuated vaccine candidates of improved safety and efficacy. Future experiments are designed to identify individual functions that govern the interaction between host and agent and control intracellular trafficking and survival. Toward this goal, this chapter describes current approaches used to mutagenize Brucella spp.
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