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Motouchi S, Komba S, Nakai H, Nakajima M. Discovery of Anomer-Inverting Transglycosylase: Cyclic Glucohexadecaose-Producing Enzyme from Xanthomonas, a Phytopathogen. J Am Chem Soc 2024; 146:17738-17746. [PMID: 38957137 PMCID: PMC11228985 DOI: 10.1021/jacs.4c02579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 06/05/2024] [Accepted: 06/07/2024] [Indexed: 07/04/2024]
Abstract
Various Xanthomonas species cause well-known plant diseases. Among various pathogenic factors, the role of α-1,6-cyclized β-1,2-glucohexadecaose (CβG16α) produced by Xanthomonas campestris pv. campestris was previously shown to be vital for infecting model organisms, Arabidopsis thaliana and Nicotiana benthamiana. However, enzymes responsible for biosynthesizing CβG16α are essentially unknown, which limits the generation of agrichemicals that inhibit CβG16α synthesis. In this study, we discovered that OpgD from X. campestris pv. campestris converts linear β-1,2-glucan to CβG16α. Structural and functional analyses revealed OpgD from X. campestris pv. campestris possesses an anomer-inverting transglycosylation mechanism, which is unprecedented among glycoside hydrolase family enzymes.
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Affiliation(s)
- Sei Motouchi
- Department
of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Shiro Komba
- Division
of Food Processing and Biomaterials Biomaterials Development Group,
Institute of Food Research, National Agriculture
and Food Research Organization, 2-1-12, Kannondai, Tsukuba, Ibaraki 305-8642, Japan
| | - Hiroyuki Nakai
- Faculty
of Agriculture, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Masahiro Nakajima
- Department
of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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2
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Gibbons E, Tamanna M, Cherayil BJ. The rpoS gene confers resistance to low osmolarity conditions in Salmonella enterica serovar Typhi. PLoS One 2022; 17:e0279372. [PMID: 36525423 PMCID: PMC9757558 DOI: 10.1371/journal.pone.0279372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022] Open
Abstract
Salmonella enterica serovars Typhimurium and Typhi are enteropathogens that differ in host range and the diseases that they cause. We found that exposure to a combination of hypotonicity and the detergent Triton X-100 significantly reduced the viability of the S. Typhi strain Ty2 but had no effect on the S. Typhimurium strain SL1344. Further analysis revealed that hypotonicity was the critical factor: incubation in distilled water alone was sufficient to kill Ty2, while the addition of sodium chloride inhibited killing in a dose-dependent manner. Ty2's loss of viability in water was modified by culture conditions: bacteria grown in well-aerated shaking cultures were more susceptible than bacteria grown under less aerated static conditions. Ty2, like many S. Typhi clinical isolates, has an inactivating mutation in the rpoS gene, a transcriptional regulator of stress responses, whereas most S. Typhimurium strains, including SL1344, have the wild-type gene. Transformation of Ty2 with a plasmid expressing wild-type rpoS, but not the empty vector, significantly increased survival in distilled water. Moreover, an S. Typhi strain with wild-type rpoS had unimpaired survival in water. Inactivation of the wild-type gene in this strain significantly reduced survival, while replacement with an arabinose-inducible allele of rpoS restored viability in water under inducing conditions. Our observations on rpoS-dependent differences in susceptibility to hypotonic conditions may be relevant to the ability of S. Typhi and S. Typhimurium to tolerate the various environments they encounter during the infectious cycle. They also have implications for the handling of these organisms during experimental manipulations.
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Affiliation(s)
- Eamon Gibbons
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - Mehbooba Tamanna
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
- Medical Sciences Program, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Bobby J. Cherayil
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
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3
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Pearson C, Tindall S, Potts JR, Thomas GH, van der Woude MW. Diverse functions for acyltransferase-3 proteins in the modification of bacterial cell surfaces. MICROBIOLOGY (READING, ENGLAND) 2022; 168:001146. [PMID: 35253642 PMCID: PMC9558356 DOI: 10.1099/mic.0.001146] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 01/21/2022] [Indexed: 12/27/2022]
Abstract
The acylation of sugars, most commonly via acetylation, is a widely used mechanism in bacteria that uses a simple chemical modification to confer useful traits. For structures like lipopolysaccharide, capsule and peptidoglycan, that function outside of the cytoplasm, their acylation during export or post-synthesis requires transport of an activated acyl group across the membrane. In bacteria this function is most commonly linked to a family of integral membrane proteins - acyltransferase-3 (AT3). Numerous studies examining production of diverse extracytoplasmic sugar-containing structures have identified roles for these proteins in O-acylation. Many of the phenotypes conferred by the action of AT3 proteins influence host colonisation and environmental survival, as well as controlling the properties of biotechnologically important polysaccharides and the modification of antibiotics and antitumour drugs by Actinobacteria. Herein we present the first systematic review, to our knowledge, of the functions of bacterial AT3 proteins, revealing an important protein family involved in a plethora of systems of importance to bacterial function that is still relatively poorly understood at the mechanistic level. By defining and comparing this set of functions we draw out common themes in the structure and mechanism of this fascinating family of membrane-bound enzymes, which, due to their role in host colonisation in many pathogens, could offer novel targets for the development of antimicrobials.
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Affiliation(s)
| | - Sarah Tindall
- Department of Biology, University of York, Heslington, UK
| | | | - Gavin H. Thomas
- Department of Biology, University of York, Heslington, UK
- York Biomedical Institute, University of York, Heslington, UK
| | - Marjan W. van der Woude
- York Biomedical Institute, University of York, Heslington, UK
- Hull York Medical School, Heslington, UK
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4
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Denamur E, Condamine B, Esposito-Farèse M, Royer G, Clermont O, Laouenan C, Lefort A, de Lastours V, Galardini M. Genome wide association study of Escherichia coli bloodstream infection isolates identifies genetic determinants for the portal of entry but not fatal outcome. PLoS Genet 2022; 18:e1010112. [PMID: 35324915 PMCID: PMC8946752 DOI: 10.1371/journal.pgen.1010112] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 02/21/2022] [Indexed: 11/19/2022] Open
Abstract
Escherichia coli is an important cause of bloodstream infections (BSI), which is of concern given its high mortality and increasing worldwide prevalence. Finding bacterial genetic variants that might contribute to patient death is of interest to better understand infection progression and implement diagnostic methods that specifically look for those factors. E. coli samples isolated from patients with BSI are an ideal dataset to systematically search for those variants, as long as the influence of host factors such as comorbidities are taken into account. Here we performed a genome-wide association study (GWAS) using data from 912 patients with E. coli BSI from hospitals in Paris, France. We looked for associations between bacterial genetic variants and three patient outcomes (death at 28 days, septic shock and admission to intensive care unit), as well as two portals of entry (urinary and digestive tract), using various clinical variables from each patient to account for host factors. We did not find any association between genetic variants and patient outcomes, potentially confirming the strong influence of host factors in influencing the course of BSI; we however found a strong association between the papGII operon and entrance of E. coli through the urinary tract, which demonstrates the power of bacterial GWAS when applied to actual clinical data. Despite the lack of associations between E. coli genetic variants and patient outcomes, we estimate that increasing the sample size by one order of magnitude could lead to the discovery of some putative causal variants. Given the wide adoption of bacterial genome sequencing of clinical isolates, such sample sizes may be soon available.
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Affiliation(s)
- Erick Denamur
- Université de Paris, IAME, UMR 1137, INSERM, Paris, France
- Laboratoire de Génétique Moléculaire, Hôpital Bichat, AP-HP, Paris, France
| | | | - Marina Esposito-Farèse
- Département d’épidémiologie, biostatistiques et recherche clinique, Hôpital Bichat, AP-HP, Paris, France
| | - Guilhem Royer
- Université de Paris, IAME, UMR 1137, INSERM, Paris, France
- LABGeM, Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Université Paris-Saclay, Evry, France
- Département de Prévention, Diagnostic et Traitement des Infections, Hôpital Henri Mondor, Créteil, France
| | | | - Cédric Laouenan
- Université de Paris, IAME, UMR 1137, INSERM, Paris, France
- Département d’épidémiologie, biostatistiques et recherche clinique, Hôpital Bichat, AP-HP, Paris, France
| | - Agnès Lefort
- Université de Paris, IAME, UMR 1137, INSERM, Paris, France
- Service de Médecine Interne, Hôpital Beaujon, AP-HP, Clichy, France
| | - Victoire de Lastours
- Université de Paris, IAME, UMR 1137, INSERM, Paris, France
- Service de Médecine Interne, Hôpital Beaujon, AP-HP, Clichy, France
| | - Marco Galardini
- Institute for Molecular Bacteriology, TWINCORE Centre for Experimental and Clinical Infection Research, a joint venture between the Hannover Medical School (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School (MHH), Hannover, Germany
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Alegun O, Pandeya A, Cui J, Ojo I, Wei Y. Donnan Potential across the Outer Membrane of Gram-Negative Bacteria and Its Effect on the Permeability of Antibiotics. Antibiotics (Basel) 2021; 10:701. [PMID: 34208097 PMCID: PMC8230823 DOI: 10.3390/antibiotics10060701] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
The cell envelope structure of Gram-negative bacteria is unique, composed of two lipid bilayer membranes and an aqueous periplasmic space sandwiched in between. The outer membrane constitutes an extra barrier to limit the exchange of molecules between the cells and the exterior environment. Donnan potential is a membrane potential across the outer membrane, resulted from the selective permeability of the membrane, which plays a pivotal role in the permeability of many antibiotics. In this review, we discussed factors that affect the intensity of the Donnan potential, including the osmotic strength and pH of the external media, the osmoregulated periplasmic glucans trapped in the periplasmic space, and the displacement of cell surface charges. The focus of our discussion is the impact of Donnan potential on the cellular permeability of selected antibiotics including fluoroquinolones, tetracyclines, β-lactams, and trimethoprim.
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Affiliation(s)
| | | | | | | | - Yinan Wei
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA; (O.A.); (A.P.); (J.C.); (I.O.)
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6
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Absence of osmoregulated periplasmic glucan confers antimicrobial resistance and increases virulence in Escherichia coli. J Bacteriol 2021; 203:e0051520. [PMID: 33846116 DOI: 10.1128/jb.00515-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clarifying the molecular mechanisms by which bacteria acquire virulence traits is important toward understanding the bacterial virulence system. In the present study, we utilized a bacterial evolution method in a silkworm-infection model and revealed that deletion of the opgGH operon encoding synthases for osmoregulated periplasmic glucan (OPG) increased the virulence of non-pathogenic laboratory strain of Escherichia coli against silkworms. The opgGH knockout mutant exhibited resistance to the host antimicrobial peptides and antibiotics. Compared with the parent strain, the opgGH knockout mutant produced greater amounts of colanic acid, which is involved in E. coli resistance to antibiotics. RNA sequence analysis revealed that the opgGH knockout altered the expression of various genes, including the evgS/evgA two-component system that functions in antibiotic resistance. In both a colanic acid-negative background and evgS-null background, the opgGH knockout increased E. coli resistance to antibiotics and increased the silkworm killing activity of E. coli In the null background of the envZ/ompR two-component system, which genetically interacts with opgGH, the opgGH knockout increased the antibiotic resistance and the virulence in silkworms. These findings suggest that the absence of OPG confers antimicrobial resistance and virulence of E. coli in a colanic acid-, evgS/evgA-, and envZ/ompR- independent manner.IMPORTANCEThe gene mutation types that increase bacterial virulence of Escherichia coli remain unclear, in part due to the limited number of methods available for isolating bacterial mutants with increased virulence. We utilized a bacterial evolution method in the silkworm infection model, in which silkworms were infected with mutagenized bacteria and highly virulent bacterial mutants were isolated from dead silkworms. We revealed that knockout of OPG synthases increases E. coli virulence against silkworms. The OPG-knockout mutants were resistant to host antimicrobial peptides as well as antibiotics. Our findings not only suggest a novel mechanism for virulence acquisition in E. coli, but also support the usefulness of utilizing the bacterial experimental evolution method in the silkworm infection model.
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7
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Meng J, Xu J, Chen J. The role of osmoregulated periplasmic glucans in the biofilm antibiotic resistance of Yersinia enterocolitica. Microb Pathog 2020; 147:104284. [PMID: 32492459 DOI: 10.1016/j.micpath.2020.104284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 05/27/2020] [Accepted: 05/27/2020] [Indexed: 12/28/2022]
Abstract
The formation of biofilms by bacteria is of great significance because it involves many physiological changes that serve to protect the cells from various stresses. One of the best-known biofilm-specific properties of bacteria is that bacteria that grow in biofilms are generally more resistant to antibiotics than their planktonic counterparts. In a previous study, osmoregulated periplasmic glucans (OPGs), catalyzed by the opgGH operon, were identified and found to function in Rcs signalling in Yersinia enterocolitica. In this study, the possible contribution of OPGs to antimicrobial resistance of Y. enterocolitica biofilms were investigated, and the results showed that OPGs, especially when overexpressed, conferred a high level of biofilm resistance to two different classes of antibiotics onto Y. enterocolitica. Subsequent analysis revealed that OPGs regulated the biofilm architecture in Y. enterocolitica by promoting the bacteria to form large cell aggregates. Moreover, the opgGH genes in biofilms showed higher expression than in planktonic cultures. OPGs were required to induce the expression of genes related to flagella, extracellular polysaccharide, and c-di-GMP biosynthesis in Y. enterocolitica biofilms and this effect was more significant when OPGs were overproduced. The current investigation showed an extension in the biological role of OPGs in Y. enterocolitica and provided a strong theoretical basis to further study this resistance mechanism at the molecular level to identify new drug targets or disinfectants for the treatment of infections caused by Y. enterocolitica within biofilms.
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Affiliation(s)
- Jiao Meng
- Beijing Laboratory for Food Quality and Safety, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing, 100083, China
| | - Jingguo Xu
- Beijing Laboratory for Food Quality and Safety, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing, 100083, China
| | - Jingyu Chen
- Beijing Laboratory for Food Quality and Safety, College of Food Science & Nutritional Engineering, China Agricultural University, Beijing, 100083, China.
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8
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Meng J, Huang C, Huang X, Liu D, Han B, Chen J. Osmoregulated Periplasmic Glucans Transmit External Signals Through Rcs Phosphorelay Pathway in Yersinia enterocolitica. Front Microbiol 2020; 11:122. [PMID: 32117145 PMCID: PMC7013093 DOI: 10.3389/fmicb.2020.00122] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/20/2020] [Indexed: 01/13/2023] Open
Abstract
Fast response to environmental changes plays a key role in the transmission and pathogenesis of Yersinia enterocolitica. Osmoregulated periplasmic glucans (OPGs) are known to be involved in environmental perception of several Enterobacteriaceae pathogens; however, the biological function of OPGs in Y. enterocolitica is still unclear. In this study, we investigated the role of OPGs in Y. enterocolitica by deleting the opgGH operon encoding enzymes responsible for OPGs biosynthesis. Complete loss of OPGs in the ΔopgGH mutant resulted in decreased motility, c-di-GMP production, biofilm formation and smaller cell size, whereas the overproduction of OPGs through restoration of opgGH expression promoted c-di-GMP/biofilm production and increased antibiotic resistance of Y. enterocolitica. Gene expression analysis revealed that opgGH deletion reduced transcription of flhDC, ftsAZ, hmsT and hmsHFRS genes regulated by the Rcs phosphorelay system, whereas additional deletion of rcs family genes (rcsF, rcsC, or rcsB) reversed this effect and restored motility and c-di-GMP/biofilm production but further reduced cell size. Furthermore, disruption of the Rcs phosphorelay increased the motility and promoted the induction of biofilm and c-di-GMP production regulated by OPGs through upregulating the expression of flhDC, hmsHFRS, and hmsT. However, deletion of genes encoding the EnvZ/OmpR phosphorelay downregulated the flhDC, hmsHFRS and hmsT expression, leading to the decreased motility and prevented the induction of biofilm and c-di-GMP production regulated by OPGs. These results indicated that Rcs phosphorelay had the effect on OPGs-mediated functional responses in Y. enterocolitica. Our findings disclose part of the biological role of OPGs and the underlying molecular mechanisms associated with Rcs system in the regulation of the pathogenic phenotype in Y. enterocolitica.
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Affiliation(s)
- Jiao Meng
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Can Huang
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Xiaoning Huang
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Dingyu Liu
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Beizhong Han
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Jingyu Chen
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
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9
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Mir DA, Balamurugan K. In vitro and in vivo efficacy of Caenorhabditis elegans recombinant antimicrobial protein against Gram-negative bacteria. BIOFOULING 2019; 35:900-921. [PMID: 31617758 DOI: 10.1080/08927014.2019.1675048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 06/10/2023]
Abstract
Antimicrobial peptides (AMPs) are short, positively charged host defense peptides, found in various life forms from microorganisms to humans. AMPs are gaining more attention as substitutes for antibiotics in order to combat the risk posed by multi-drug- resistant pathogens. The nematode Caenorhabditis elegans relies solely on its innate immune defense to cope with its challenging life-style. Bacterial infection in C. elegans leads to induction of antimicrobial proteins, defensins, nemapores, cecropins, and neuropeptide-like proteins, which act to limit bacterial proliferation. This study reports how the C. elegans recombinant antibacterial factor (ABF-1) rapidly inhibited bacterial growth (Salmonella Typhi, Klebsiella pneumonia, Shigella sonnei and Vibrio alginolyticus). The ABF-1 exposure on S. Typhi, showed differential regulation in cell-cycle, DNA repair mechanism, membrane stability, and stress related proteins. The exogenous supply of ABF-1 protein has extended C. elegans survival by reducing the bacterial colony forming units on the nematode intestine. Together, these findings indicate the valuable and potential therapeutic applications of ABF-1 protein as antimicrobial agents against intracellular pathogens.
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10
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An Osmoregulatory Mechanism Operating through OmpR and LrhA Controls the Motile-Sessile Switch in the Plant Growth-Promoting Bacterium Pantoea alhagi. Appl Environ Microbiol 2019; 85:AEM.00077-19. [PMID: 30902852 DOI: 10.1128/aem.00077-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 03/14/2019] [Indexed: 11/20/2022] Open
Abstract
Adaptation to osmotic stress is crucial for bacterial growth and survival in changing environments. Although a large number of osmotic stress response genes have been identified in various bacterial species, how osmotic changes affect bacterial motility, biofilm formation, and colonization of host niches remains largely unknown. In this study, we report that the LrhA regulator is an osmoregulated transcription factor that directly binds to the promoters of the flhDC, eps, and opgGH operons and differentially regulates their expression, thus inhibiting motility and promoting exopolysaccharide (EPS) production, synthesis of osmoregulated periplasmic glucans (OPGs), biofilm formation, and root colonization of the plant growth-promoting bacterium Pantoea alhagi LTYR-11Z. Further, we observed that the LrhA-regulated OPGs control RcsCD-RcsB activation in a concentration-dependent manner, and a high concentration of OPGs induced by increased medium osmolarity is maintained to achieve the high level of activation of the Rcs phosphorelay, which results in enhanced EPS synthesis and decreased motility in P. alhagi Moreover, we showed that the osmosensing regulator OmpR directly binds to the promoter of lrhA and promotes its expression, while lrhA expression is feedback inhibited by the activated Rcs phosphorelay system. Overall, our data support a model whereby P. alhagi senses environmental osmolarity changes through the EnvZ-OmpR two-component system and LrhA to regulate the synthesis of OPGs, EPS production, and flagellum-dependent motility, thereby employing a hierarchical signaling cascade to control the transition between a motile lifestyle and a biofilm lifestyle.IMPORTANCE Many motile bacterial populations form surface-attached biofilms in response to specific environmental cues, including osmotic stress in a range of natural and host-related systems. However, cross talk between bacterial osmosensing, swimming, and biofilm formation regulatory networks is not fully understood. Here, we report that the pleiotropic regulator LrhA in Pantoea alhagi is involved in the regulation of flagellar motility, biofilm formation, and host colonization and responds to osmotic upshift. We further show that this sensing relies on the EnvZ-OmpR two-component system that was known to detect changes in external osmotic stress. The EnvZ-OmpR-LrhA osmosensing signal transduction cascade is proposed to increase bacterial fitness under hyperosmotic conditions inside the host. Our work proposes a novel regulatory mechanism that links osmosensing and motile-sessile lifestyle transitions, which may provide new approaches to prevent or promote the formation of biofilms and host colonization in P. alhagi and other bacteria possessing a similar osmoregulatory mechanism.
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11
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Caby M, Bontemps-Gallo S, Gruau P, Delrue B, Madec E, Lacroix JM. The EnvZ-OmpR Two-Component Signaling System Is Inactivated in a Mutant Devoid of Osmoregulated Periplasmic Glucans in Dickeya dadantii. Front Microbiol 2018; 9:2459. [PMID: 30425688 PMCID: PMC6218677 DOI: 10.3389/fmicb.2018.02459] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 09/25/2018] [Indexed: 12/04/2022] Open
Abstract
Osmoregulated periplasmic glucans (OPGs) are general constituents of alpha-, beta-, and gamma-Proteobacteria. This polymer of glucose is required for full virulence of many pathogens including Dickeya dadantii (D. dadantii). The phytopathogenic enterobacterium D. dadantii causes soft-rot disease in a wide range of plants. An OPG-defective mutant is impaired in environment sensing. We previously demonstrated that (i) fluctuation of OPG concentration controlled the activation level of the RcsCDB system, and (ii) RcsCDB along with EnvZ/OmpR controlled the mechanism of OPG succinylation. These previous data lead us to explore whether OPGs are required for other two-component systems. In this study, we demonstrate that inactivation of the EnvZ/OmpR system in an OPG-defective mutant restores full synthesis of pectinase but only partial virulence. Unlike for the RcsCDB system, the EnvZ-OmpR system is not controlled by OPG concentration but requires OPGs for proper activation.
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Affiliation(s)
- Marine Caby
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, Université des Sciences et Technologies de Lille, Université de Lille, Lille, France
| | - Sébastien Bontemps-Gallo
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, Université des Sciences et Technologies de Lille, Université de Lille, Lille, France
| | - Peggy Gruau
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, Université des Sciences et Technologies de Lille, Université de Lille, Lille, France
| | | | - Edwige Madec
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, Université des Sciences et Technologies de Lille, Université de Lille, Lille, France
| | - Jean-Marie Lacroix
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, Université des Sciences et Technologies de Lille, Université de Lille, Lille, France
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12
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Amar A, Pezzoni M, Pizarro RA, Costa CS. New envelope stress factors involved in σ E activation and conditional lethality of rpoE mutations in Salmonella enterica. MICROBIOLOGY-SGM 2018; 164:1293-1307. [PMID: 30084765 DOI: 10.1099/mic.0.000701] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Salmonella enterica serovar Typhimurium (S. typhimurium) can cause food- and water-borne illness with diverse clinical manifestations. One key factor for S. typhimurium pathogenesis is the alternative sigma factor σE, which is encoded by the rpoE gene and controls the transcription of genes required for outer-membrane integrity in response to alterations in the bacterial envelope. The canonical pathway for σE activation involves proteolysis of the antisigma factor RseA, which is triggered by unfolded outer-membrane porins (OMPs) and lipopolysaccharides (LPS) that have accumulated in the periplasm. This study reports new stress factors that are able to activate σE expression. We demonstrate that UVA radiation induces σE activity in a pathway that is dependent on the stringent response regulator ppGpp. Survival assays revealed that rpoE has a role in the defence against lethal UVA doses that is mediated by functions that are dependent on and independent of the alternative sigma factor RpoS. We also report that the envelope stress generated by phage infection requires a functional rpoE gene for optimal bacterial tolerance and that it is able to induce σE activity in an RseA-dependent fashion. σE activity is also induced by hypo-osmotic shock in the absence of osmoregulated periplasmic glucans (OPGs). It is known that the rpoE gene is not essential in S. typhimurium. However, we report here two cases of the conditional lethality of rpoE mutations in this micro-organism. We demonstrate that rpoE mutations are not tolerated in the absence of OPGs (at low to moderate osmolarity) or LPS O-antigen. The latter case resembles that of the prototypic Escherichia coli strain K12, which neither synthesizes a complete LPS nor tolerates null rpoE mutations.
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Affiliation(s)
- Agustina Amar
- Dpto. de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina
| | - Magdalena Pezzoni
- Dpto. de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina
| | - Ramón A Pizarro
- Dpto. de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina
| | - Cristina S Costa
- Dpto. de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina
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Bohm K, Porwollik S, Chu W, Dover JA, Gilcrease EB, Casjens SR, McClelland M, Parent KN. Genes affecting progression of bacteriophage P22 infection in Salmonella identified by transposon and single gene deletion screens. Mol Microbiol 2018; 108:288-305. [PMID: 29470858 PMCID: PMC5912970 DOI: 10.1111/mmi.13936] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2018] [Indexed: 12/20/2022]
Abstract
Bacteriophages rely on their hosts for replication, and many host genes critically determine either viral progeny production or host success via phage resistance. A random insertion transposon library of 240,000 mutants in Salmonella enterica serovar Typhimurium was used to monitor effects of individual bacterial gene disruptions on bacteriophage P22 lytic infection. These experiments revealed candidate host genes that alter the timing of phage P22 propagation. Using a False Discovery Rate of < 0.1, mutations in 235 host genes either blocked or delayed progression of P22 lytic infection, including many genes for which this role was previously unknown. Mutations in 77 genes reduced the survival time of host DNA after infection, including mutations in genes for enterobacterial common antigen (ECA) synthesis and osmoregulated periplasmic glucan (OPG). We also screened over 2000 Salmonella single gene deletion mutants to identify genes that impacted either plaque formation or culture growth rates. The gene encoding the periplasmic membrane protein YajC was newly found to be essential for P22 infection. Targeted mutagenesis of yajC shows that an essentially full-length protein is required for function, and potassium efflux measurements demonstrated that YajC is critical for phage DNA ejection across the cytoplasmic membrane.
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Affiliation(s)
- Kaitlynne Bohm
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Steffen Porwollik
- Department of Microbiology and Molecular Genetics, University of California, School of Medicine, Irvine, California 92697, USA
| | - Weiping Chu
- Department of Microbiology and Molecular Genetics, University of California, School of Medicine, Irvine, California 92697, USA
| | - John A Dover
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Eddie B Gilcrease
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Sherwood R Casjens
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Michael McClelland
- Department of Microbiology and Molecular Genetics, University of California, School of Medicine, Irvine, California 92697, USA
| | - Kristin N Parent
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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Role of sapA and yfgA in Susceptibility to Antibody-Mediated Complement-Dependent Killing and Virulence of Salmonella enterica Serovar Typhimurium. Infect Immun 2017; 85:IAI.00419-17. [PMID: 28674031 PMCID: PMC5563563 DOI: 10.1128/iai.00419-17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 06/16/2017] [Indexed: 01/18/2023] Open
Abstract
The ST313 pathovar of Salmonella enterica serovar Typhimurium contributes to a high burden of invasive disease among African infants and HIV-infected adults. It is characterized by genome degradation (loss of coding capacity) and has increased resistance to antibody-dependent complement-mediated killing compared with enterocolitis-causing strains of S. Typhimurium. Vaccination is an attractive disease-prevention strategy, and leading candidates focus on the induction of bactericidal antibodies. Antibody-resistant strains arising through further gene deletion could compromise such a strategy. Exposing a saturating transposon insertion mutant library of S. Typhimurium to immune serum identified a repertoire of S. Typhimurium genes that, when interrupted, result in increased resistance to serum killing. These genes included several involved in bacterial envelope biogenesis, protein translocation, and metabolism. We generated defined mutant derivatives using S. Typhimurium SL1344 as the host. Based on their initial levels of enhanced resistance to killing, yfgA and sapA mutants were selected for further characterization. The S. Typhimurium yfgA mutant lost the characteristic Salmonella rod-shaped appearance, exhibited increased sensitivity to osmotic and detergent stress, lacked very long lipopolysaccharide, was unable to invade enterocytes, and demonstrated decreased ability to infect mice. In contrast, the S. Typhimurium sapA mutants had similar sensitivity to osmotic and detergent stress and lipopolysaccharide profile and an increased ability to infect enterocytes compared with the wild type, but it had no increased ability to cause in vivo infection. These findings indicate that increased resistance to antibody-dependent complement-mediated killing secondary to genetic deletion is not necessarily accompanied by increased virulence and suggest the presence of different mechanisms of antibody resistance.
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Bhagwat AA, Young L, Smith AD, Bhagwat M. Transcriptomic Analysis of the Swarm Motility Phenotype of Salmonella enterica Serovar Typhimurium Mutant Defective in Periplasmic Glucan Synthesis. Curr Microbiol 2017; 74:1005-1014. [PMID: 28593349 DOI: 10.1007/s00284-017-1267-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 05/14/2017] [Indexed: 12/19/2022]
Abstract
Movement of food-borne pathogens on moist surfaces enables them to migrate towards more favorable niches and facilitate their survival for extended periods of time. Salmonella enterica serovar Typhimurium mutants defective in Osmoregulated periplasmic glucans (OPG) synthesis are unable to exhibit motility on moist surfaces (swarming); however, their mobility in liquid (swim motility) remains unaffected. In order to understand the role of OPG in swarm motility, transcriptomic analysis was performed using cells growing on a moist agar surface. In opgGH deletion mutant, lack of OPG significantly altered transcription of 1039 genes out of total 4712 genes (22%). Introduction of a plasmid-borne copy of opgGH into opgGH deletion mutant restored normal expression of all but 30 genes, indicating a wide-range influence of OPG on gene expression under swarm motility condition. Major pathways that were differentially expressed in opgGH mutants were motility, virulence and invasion, and genes related to the secondary messenger molecule, cyclic di-GMP. These observations provide insights and help explain the pleiotropic nature of OPG mutants such as sub-optimal virulence and competitive organ colonization in mice, biofilm formation, and sensitivity towards detergent stress.
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Affiliation(s)
- Arvind A Bhagwat
- Environmental, Microbial, & Food Safety Laboratory, Beltsville Agriculture Research Center, USDA-ARS (USDA/ARS/EMFSL), 10300 Baltimore Ave., B173, Rm. 204, BARC-E, Beltsville, MD, 20705, USA.
| | - Lynn Young
- National Institutes of Health Library, Division of Library Services, Office of Research Services, National Institute of Health, Building 10, Bethesda, MD, 20892, USA
| | - Allen D Smith
- Diet, Genomics and Immunology Laboratory, Beltsville Human Nutrition Research Center, USDA-ARS, Beltsville, MD, 20705, USA.
| | - Medha Bhagwat
- National Institutes of Health Library, Division of Library Services, Office of Research Services, National Institute of Health, Building 10, Bethesda, MD, 20892, USA
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Abstract
Among all the systems developed by enterobacteria to face osmotic stress, only osmoregulated periplasmic glucans (OPGs) were found to be modulated during osmotic fluxes. First detected in 1973 by E.P. Kennedy's group in a study of phospholipid turnover in Escherichia coli, OPGs have been shown across alpha, beta, and gamma subdivisions of the proteobacteria. Discovery of OPG-like compounds in the epsilon subdivision strongly suggested that the presence of periplasmic glucans is essential for almost all proteobacteria. This article offers an overview of the different classes of OPGs. Then, the biosynthesis of OPGs and their regulation in E. coli and other species are discussed. Finally, the biological role of OPGs is developed. Beyond structural function, OPGs are involved in pathogenicity, in particular, by playing a role in signal transduction pathways. Recently, OPG synthesis proteins have been suggested to control cell division and growth rate.
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Affiliation(s)
- Sébastien Bontemps-Gallo
- Univ. Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F 59000 Lille, France
| | - Jean-Pierre Bohin
- Univ. Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F 59000 Lille, France
| | - Jean-Marie Lacroix
- Univ. Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F 59000 Lille, France
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Bontemps-Gallo S, Lacroix JM. New insights into the biological role of the osmoregulated periplasmic glucans in pathogenic and symbiotic bacteria. ENVIRONMENTAL MICROBIOLOGY REPORTS 2015; 7:690-7. [PMID: 26265506 PMCID: PMC4618058 DOI: 10.1111/1758-2229.12325] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 07/24/2015] [Accepted: 07/31/2015] [Indexed: 05/06/2023]
Abstract
This review emphasizes the biological roles of the osmoregulated periplasmic glucans (OPGs). Osmoregulated periplasmic glucans occur in almost all α-, β- and γ-Proteobacteria. This polymer of glucose is required for full virulence. The roles of the OPGs are complex and vary depending on the species. Here, we outline the four major roles of the OPGs through four different pathogenic and one symbiotic bacterial models (Dickeya dadantii, Salmonella enterica, Pseudomonas aeruginosa, Brucella abortus and Sinorhizobium meliloti). When periplasmic, the OPGs are a part of the signal transduction pathway and indirectly regulate genes involved in virulence. The OPGs can also be secreted. When outside of the cell, they interact directly with antibiotics to protect the bacterial cell or interact with the host cell to facilitate the invasion process. When OPGs are not found, as in the ε-Proteobacteria, OPG-like oligosaccharides are present. Their presence strengthens the evidence that OPGs play an important role in virulence.
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Affiliation(s)
- Sébastien Bontemps-Gallo
- Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 South 4th Street, Hamilton, MT, 59840, USA. Phone: +1 (406) 363-9259.
| | - Jean-Marie Lacroix
- Structural and Functional Glycobiology Unit, UMR CNRS-Lille1 8576, University of Lille, 59655 Villeneuve d’Ascq cedex, France. Phone: +33 3 20 43 65 92.
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The Identification of Genes Important in Pseudomonas syringae pv. phaseolicola Plant Colonisation Using In Vitro Screening of Transposon Libraries. PLoS One 2015; 10:e0137355. [PMID: 26325299 PMCID: PMC4556710 DOI: 10.1371/journal.pone.0137355] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 08/15/2015] [Indexed: 01/18/2023] Open
Abstract
The bacterial plant pathogen Pseudomonas syringae pv. phaseolicola (Pph) colonises the surface of common bean plants before moving into the interior of plant tissue, via wounds and stomata. In the intercellular spaces the pathogen proliferates in the apoplastic fluid and forms microcolonies (biofilms) around plant cells. If the pathogen can suppress the plant’s natural resistance response, it will cause halo blight disease. The process of resistance suppression is fairly well understood, but the mechanisms used by the pathogen in colonisation are less clear. We hypothesised that we could apply in vitro genetic screens to look for changes in motility, colony formation, and adhesion, which are proxies for infection, microcolony formation and cell adhesion. We made transposon (Tn) mutant libraries of Pph strains 1448A and 1302A and found 106/1920 mutants exhibited alterations in colony morphology, motility and biofilm formation. Identification of the insertion point of the Tn identified within the genome highlighted, as expected, a number of altered motility mutants bearing mutations in genes encoding various parts of the flagellum. Genes involved in nutrient biosynthesis, membrane associated proteins, and a number of conserved hypothetical protein (CHP) genes were also identified. A mutation of one CHP gene caused a positive increase in in planta bacterial growth. This rapid and inexpensive screening method allows the discovery of genes important for in vitro traits that can be correlated to roles in the plant interaction.
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Evaluation of the Role of the opgGH Operon in Yersinia pseudotuberculosis and Its Deletion during the Emergence of Yersinia pestis. Infect Immun 2015; 83:3638-47. [PMID: 26150539 DOI: 10.1128/iai.00482-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 06/26/2015] [Indexed: 02/02/2023] Open
Abstract
The opgGH operon encodes glucosyltransferases that synthesize osmoregulated periplasmic glucans (OPGs) from UDP-glucose, using acyl carrier protein (ACP) as a cofactor. OPGs are required for motility, biofilm formation, and virulence in various bacteria. OpgH also sequesters FtsZ in order to regulate cell size according to nutrient availability. Yersinia pestis (the agent of flea-borne plague) lost the opgGH operon during its emergence from the enteropathogen Yersinia pseudotuberculosis. When expressed in OPG-negative strains of Escherichia coli and Dickeya dadantii, opgGH from Y. pseudotuberculosis restored OPGs synthesis, motility, and virulence. However, Y. pseudotuberculosis did not produce OPGs (i) under various growth conditions or (ii) when overexpressing its opgGH operon, its galUF operon (governing UDP-glucose), or the opgGH operon or Acp from E. coli. A ΔopgGH Y. pseudotuberculosis strain showed normal motility, biofilm formation, resistance to polymyxin and macrophages, and virulence but was smaller. Consistently, Y. pestis was smaller than Y. pseudotuberculosis when cultured at ≥ 37°C, except when the plague bacillus expressed opgGH. Y. pestis expressing opgGH grew normally in serum and within macrophages and was fully virulent in mice, suggesting that small cell size was not advantageous in the mammalian host. Lastly, Y. pestis expressing opgGH was able to infect Xenopsylla cheopis fleas normally. Our results suggest an evolutionary scenario whereby an ancestral Yersinia strain lost a factor required for OPG biosynthesis but kept opgGH (to regulate cell size). The opgGH operon was presumably then lost because OpgH-dependent cell size control became unnecessary.
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Mahadwar G, Chauhan KR, Bhagavathy GV, Murphy C, Smith AD, Bhagwat AA. Swarm motility of Salmonella enterica serovar Typhimurium is inhibited by compounds from fruit peel extracts. Lett Appl Microbiol 2015; 60:334-40. [PMID: 25422036 DOI: 10.1111/lam.12364] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 10/28/2014] [Accepted: 11/17/2014] [Indexed: 01/02/2023]
Abstract
UNLABELLED Controlling spread of human pathogens on fresh produce is a top priority for public health reasons. Isolation of compounds from agricultural waste that would control spread of human pathogens was explored using Salmonella enterica serovar Typhimurium as a model organism. In the environment, micro-organisms migrate as a 'community' especially when they move on moist surfaces. This type of motility is characterized as swarming motility. We examined extracts from agricultural waste such as soya bean husk, peels of orange, pineapple, avocado and pomegranate for antiswarming activity. Avocado and pineapple peels showed moderate (~40%) inhibition of swarming motility while pomegranate peel extract had high antiswarming activity (~85% inhibition) and was examined in further detail. Although the pomegranate peel extract was acidic, swarm-inhibitory activity was not due to low pH and the peel extract did not inhibit growth of Salmonella. Among the key swarm motility regulatory genes, class II (fliF, fliA, fliT and fliZ) and class III (fliC and fliM) regulators were downregulated upon exposure to pomegranate peel extract. Pomegranate peels offer great potential as a bioactive repellent for pathogenic micro-organisms on moist surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY Controlling the spread of food-borne pathogens in moist environments is an important microbial food safety issue. Isolation of compounds from agricultural waste (such as fruit peels) that would control spread of human pathogens was explored using Salmonella enterica serovar Typhimurium as a model organism. Pomegranate peels offer great potential as a bioactive repellent for pathogenic micro-organisms.
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Affiliation(s)
- G Mahadwar
- Environmental Microbial & Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD, USA
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Dharne MS, Kannan P, Murphy C, Smith AD, Bhagwat AA. Swarm and swim motilities of Salmonella enterica serovar Typhimurium and role of osmoregulated periplasmic glucans. ACTA ACUST UNITED AC 2015. [DOI: 10.7243/2052-6180-3-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Percy MG, Gründling A. Lipoteichoic Acid Synthesis and Function in Gram-Positive Bacteria. Annu Rev Microbiol 2014; 68:81-100. [DOI: 10.1146/annurev-micro-091213-112949] [Citation(s) in RCA: 266] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Matthew G. Percy
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ UK; ,
| | - Angelika Gründling
- Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ UK; ,
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Bhagwat AA, Ying ZI, Smith A. Evaluation of Ribosomal RNA Removal Protocols for <i>Salmonella</i> RNA-Seq Projects. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/aim.2014.41006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Bontemps-Gallo S, Cogez V, Robbe-Masselot C, Quintard K, Dondeyne J, Madec E, Lacroix JM. Biosynthesis of osmoregulated periplasmic glucans in Escherichia coli: the phosphoethanolamine transferase is encoded by opgE. BIOMED RESEARCH INTERNATIONAL 2013; 2013:371429. [PMID: 24228245 PMCID: PMC3818809 DOI: 10.1155/2013/371429] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/30/2013] [Accepted: 09/02/2013] [Indexed: 11/18/2022]
Abstract
Osmoregulated periplasmic glucans (OPGs) are oligosaccharides found in the periplasm of many Gram-negative bacteria. Glucose is the sole constitutive sugar and this backbone may be substituted by various kinds of molecules depending on the species. In E. coli, OPG are substituted by phosphoglycerol and phosphoethanolamine derived from membrane phospholipids and by succinyl residues. In this study, we describe the isolation of the opgE gene encoding the phosphoethanolamine transferase by a screen previously used for the isolation of the opgB gene encoding the phosphoglycerol transferase. Both genes show structural and functional similarities without sequence similarity.
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Affiliation(s)
- Sébastien Bontemps-Gallo
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
- Université Lille Nord de France, Lille, France
| | - Virginie Cogez
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
- Université Lille Nord de France, Lille, France
| | - Catherine Robbe-Masselot
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
- Université Lille Nord de France, Lille, France
| | - Kevin Quintard
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
- Université Lille Nord de France, Lille, France
| | - Jacqueline Dondeyne
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
- Université Lille Nord de France, Lille, France
| | - Edwige Madec
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
- Université Lille Nord de France, Lille, France
| | - Jean-Marie Lacroix
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
- Université Lille Nord de France, Lille, France
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Hill NS, Buske PJ, Shi Y, Levin PA. A moonlighting enzyme links Escherichia coli cell size with central metabolism. PLoS Genet 2013; 9:e1003663. [PMID: 23935518 PMCID: PMC3723540 DOI: 10.1371/journal.pgen.1003663] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 06/08/2013] [Indexed: 11/18/2022] Open
Abstract
Growth rate and nutrient availability are the primary determinants of size in single-celled organisms: rapidly growing Escherichia coli cells are more than twice as large as their slow growing counterparts. Here we report the identification of the glucosyltransferase OpgH as a nutrient-dependent regulator of E. coli cell size. During growth under nutrient-rich conditions, OpgH localizes to the nascent septal site, where it antagonizes assembly of the tubulin-like cell division protein FtsZ, delaying division and increasing cell size. Biochemical analysis is consistent with OpgH sequestering FtsZ from growing polymers. OpgH is functionally analogous to UgtP, a Bacillus subtilis glucosyltransferase that inhibits cell division in a growth rate-dependent fashion. In a striking example of convergent evolution, OpgH and UgtP share no homology, have distinct enzymatic activities, and appear to inhibit FtsZ assembly through different mechanisms. Comparative analysis of E. coli and B. subtilis reveals conserved aspects of growth rate regulation and cell size control that are likely to be broadly applicable. These include the conservation of uridine diphosphate glucose as a proxy for nutrient status and the use of moonlighting enzymes to couple growth rate-dependent phenomena to central metabolism. The observation that growth rate and nutrient availability strongly influence bacterial cell size was made over forty years ago. Yet, the molecular mechanisms responsible for this phenomenon have remained elusive. Using a genetic approach, we identified proteins responsible for increasing Escherichia coli cell size under nutrient-rich conditions. Our data indicate that OpgH, a glucosyltransferase involved in cell envelope biogenesis, interacts with FtsZ, a key component of the bacterial cell division machinery. In the presence of a modified sugar, UDP-glucose, OpgH interacts with FtsZ to delay the timing of division machinery assembly. Comparison of the E. coli pathway with the parallel Bacillus subtilis pathway illuminates a striking example of convergent evolution in which two highly divergent bacteria employ unrelated glucosyltransferases for an essential part of cell cycle regulation and reveals aspects of metabolic and physiological control that are potentially applicable to all forms of life.
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Affiliation(s)
- Norbert S. Hill
- Department of Biology, Washington University, Saint Louis, Missouri, United States of America
| | - Paul J. Buske
- Department of Biology, Washington University, Saint Louis, Missouri, United States of America
| | - Yue Shi
- Department of Biology, Washington University, Saint Louis, Missouri, United States of America
| | - Petra Anne Levin
- Department of Biology, Washington University, Saint Louis, Missouri, United States of America
- * E-mail:
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Smith A, Bhagwat AA. Hypervirulent-host-associated Citrobacter rodentium cells have poor acid tolerance. Curr Microbiol 2013; 66:522-6. [PMID: 23328901 DOI: 10.1007/s00284-012-0298-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/16/2012] [Indexed: 12/22/2022]
Abstract
Enhanced virulence or infectivity after passage through a mammalian host has been reported for a number of enteric food-borne pathogens. Citrobacter rodentium is a mouse pathogen that mimics many aspects of enterohemorrhagic Escherichia coli infection of humans and serves as a useful model for studying virulence mechanisms. Emergence of a hyperinfectious state after passage through mouse gastrointestinal tract was reported for C. rodentium. We wanted to investigate if increased acid tolerance could explain hypervirulence status of C. rodentium. Although we were able to observe hyperinfectious state of C. rodentium upon host passage, the cells were extremely acid sensitive. Growth under mildly acidic conditions (LB-MES, pH 5.5) induced acid tolerance of C. rodentium, but did not improve the organism's ability to establish infection. Growth under anaerobic environment on fecal components also did not induce hyperinfectious state. Thus, contrary to conventional anticipation, hypervirulent C. rodentium cells were found to be acid sensitive thereby revealing limitations of the role of mouse gastric acidity by itself in elucidating the hypervirulent phenotype.
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Affiliation(s)
- Allen Smith
- Diet Genomics and Immunology and Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, 10300 Baltimore Avenue, BARC-E, Beltsville, MD 20705-2350, USA
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Bhagwat AA, Ying ZI, Karns J, Smith A. Determining RNA quality for NextGen sequencing: some exceptions to the gold standard rule of 23S to 16S rRNA ratio§. ACTA ACUST UNITED AC 2013. [DOI: 10.7243/2052-6180-1-10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bontemps-Gallo S, Madec E, Dondeyne J, Delrue B, Robbe-Masselot C, Vidal O, Prouvost AF, Boussemart G, Bohin JP, Lacroix JM. Concentration of osmoregulated periplasmic glucans (OPGs) modulates the activation level of the RcsCD RcsB phosphorelay in the phytopathogen bacteria Dickeya dadantii. Environ Microbiol 2012; 15:881-94. [PMID: 23253096 DOI: 10.1111/1462-2920.12054] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 11/14/2012] [Indexed: 11/26/2022]
Abstract
Osmoregulated periplasmic glucans (OPGs) are general constituents of many Proteobacteria. Synthesis of these oligosaccharides is repressed by increased osmolarity of the medium. OPGs are important factors required for full virulence in many zoo- or phytopathogens including Dickeya dadantii. The phytopathogen enterobacterium D. dadantii causes soft-rot disease on a wide range of plant species. The total loss of virulence of opg-negative strains of D. dadantii is linked to the constitutive activation of the RcsCD RcsB phosphorelay highlighting relationship between this phosphorelay and OPGs. Here we show that OPGs control the RcsCD RcsB activation in a concentration-dependent manner, are required for proper activation of this phosphorelay by medium osmolarity, and a high concentration of OPGs in planta is maintained to achieve the low level of activation of the RcsCD RcsB phosphorelay required for full virulence in D. dadantii.
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Affiliation(s)
- Sébastien Bontemps-Gallo
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655, Villeneuve d'Ascq, France
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Bhagwat AA, Leow YN, Liu L, Dharne M, Kannan P. Role of Anionic Charges of Periplasmic Glucans ofShigella flexneriin Overcoming Detergent Stress. Foodborne Pathog Dis 2012; 9:632-7. [PMID: 22730962 DOI: 10.1089/fpd.2011.1090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- Arvind A. Bhagwat
- Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland
| | - Yi Ning Leow
- Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland
| | - Liu Liu
- Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland
| | - Mahesh Dharne
- Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland
| | - Porteen Kannan
- Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland
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Cooper B, Chen R, Garrett WM, Murphy C, Chang C, Tucker ML, Bhagwat AA. Proteomic Pleiotropy of OpgGH, an Operon Necessary for Efficient Growth of Salmonella enterica serovar Typhimurium under Low-Osmotic Conditions. J Proteome Res 2012; 11:1720-7. [DOI: 10.1021/pr200933d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
| | - Ruiqiang Chen
- Department of Cell Biology and
Molecular Genetics, University of Maryland, College Park, Maryland 20742, United States
| | | | | | - Caren Chang
- Department of Cell Biology and
Molecular Genetics, University of Maryland, College Park, Maryland 20742, United States
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Bhagwat AA, Kannan P, Leow YN, Dharne M, Smith A. Role of anionic charges of osmoregulated periplasmic glucans of Salmonella enterica serovar Typhimurium SL1344 in mice virulence. Arch Microbiol 2012; 194:541-8. [PMID: 22278765 DOI: 10.1007/s00203-012-0791-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 12/16/2011] [Accepted: 01/04/2012] [Indexed: 01/17/2023]
Abstract
opgB gene of Salmonella enterica serovar Typhimurium was identified earlier in a genome-wide screen for mice virulence (Valentine et al. in Infect Immun 66:3378-3383, 1998). Although mutation in opgB resulted in avirulent Salmonella strain, how this gene contributes to pathogenesis remains unclear. Based on DNA homology, opgB is predicted to be responsible for adding phosphoglycerate residues to osmoregulated periplasmic glucans (OPGs) giving them anionic characteristics. In Escherichia coli, yet another gene, opgC, is also reported to contribute to anionic characteristics of OPGs by adding succinic acid residues. We constructed opgB, opgC, and opgBC double mutants of S. enterica serovar Typhimurium strain SL1344. As predicted opgBC mutant synthesized neutral OPGs that were devoid of any anionic substituents. However, opgB, opgC, and opgBC mutations had no significant impact on mice virulence as well as on competitive organ colonization. In low osmotic conditions, opgB, opgC, and opgBC mutants exhibited delay in growth initiation in the presence of sodium deoxycholate. Anionic substituents of OPGs from Salmonella although appear to be needed to overcome resistance of deoxycholate in hypoosmotic growth media, no evidence was found for their role in mice virulence.
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Affiliation(s)
- Arvind A Bhagwat
- Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, 10300 Baltimore Avenue, Bldg. 173, BARC-E, Beltsville, MD 20705-2350, USA.
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Abstract
Elongation factor P (EF-P) is posttranslationally modified at a conserved lysyl residue by the coordinated action of two enzymes, PoxA and YjeK. We have previously established the importance of this modification in Salmonella stress resistance. Here we report that, like poxA and yjeK mutants, Salmonella strains lacking EF-P display increased susceptibility to hypoosmotic conditions, antibiotics, and detergents and enhanced resistance to the compound S-nitrosoglutathione. The susceptibility phenotypes are largely explained by the enhanced membrane permeability of the efp mutant, which exhibits increased uptake of the hydrophobic dye 1-N-phenylnaphthylamine (NPN). Analysis of the membrane proteomes of wild-type and efp mutant Salmonella strains reveals few changes, including the prominent overexpression of a single porin, KdgM, in the efp mutant outer membrane. Removal of KdgM in the efp mutant background ameliorates the detergent, antibiotic, and osmosensitivity phenotypes and restores wild-type permeability to NPN. Our data support a role for EF-P in the translational regulation of a limited number of proteins that, when perturbed, renders the cell susceptible to stress by the adventitious overexpression of an outer membrane porin.
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Bouchart F, Boussemart G, Prouvost AF, Cogez V, Madec E, Vidal O, Delrue B, Bohin JP, Lacroix JM. The virulence of a Dickeya dadantii 3937 mutant devoid of osmoregulated periplasmic glucans is restored by inactivation of the RcsCD-RcsB phosphorelay. J Bacteriol 2010; 192:3484-90. [PMID: 20418397 PMCID: PMC2897653 DOI: 10.1128/jb.00143-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 04/14/2010] [Indexed: 11/20/2022] Open
Abstract
Dickeya dadantii is a pectinolytic phytopathogen enterobacterium that causes soft rot disease on a wide range of plant species. The virulence of D. dadantii involves several factors, including the osmoregulated periplasmic glucans (OPGs) that are general constituents of the envelope of proteobacteria. In addition to the loss of virulence, opg-negative mutants display a pleiotropic phenotype, including decreased motility and increased exopolysaccharide synthesis. A nitrosoguanidine-induced mutagenesis was performed on the opgG strain, and restoration of motility was used as a screen. The phenotype of the opg mutant echoes that of the Rcs system: high level activation of the RcsCD-RcsB phosphorelay is needed to activate exopolysaccharide synthesis and to repress motility, while low level activation is required for virulence in enterobacteria. Here, we show that mutations in the RcsCDB phosphorelay system restored virulence and motility in a D. dadantii opg-negative strain, indicating a relationship between the Rcs phosphorelay and OPGs.
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Affiliation(s)
- Franck Bouchart
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Gilles Boussemart
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Anne-France Prouvost
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Virginie Cogez
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Edwige Madec
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Olivier Vidal
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Brigitte Delrue
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Jean-Pierre Bohin
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Jean-Marie Lacroix
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
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Liu L, Dharne M, Kannan P, Smith A, Meng J, Fan M, Boren TL, Ranallo RT, Bhagwat AA. Osmoregulated periplasmic glucans synthesis gene family of Shigella flexneri. Arch Microbiol 2010; 192:167-74. [PMID: 20062978 DOI: 10.1007/s00203-009-0538-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 11/20/2009] [Accepted: 12/17/2009] [Indexed: 11/29/2022]
Abstract
UNLABELLED Osmoregulated periplasmic glucans (OPGs) of food- and water-borne enteropathogen Shigella flexneri were characterized. OPGs were composed of 100% glucose with 2-linked glucose as the most abundant residue with terminal glucose, 2-linked and 2,6-linked glucose also present in high quantities. Most dominant backbone polymer chain length was seven glucose residues. Individual genes from the opg gene family comprising of a bicistronic operon opgGH, opgB, opgC and opgD were mutagenized to study their effect on OPGs synthesis, growth in hypo-osmotic media and ability to invade HeLa cells. Mutation in opgG and opgH abolished OPGs biosynthesis, and mutants experienced longer lag time to initiate growth in hypo-osmotic media. Longer lag times to initiate growth in hypo-osmotic media were also observed for opgC and opgD mutants but not for opgB mutant. All opg mutants were able to infect HeLa cells, and abolition of OPGs synthesis did not affect actin polymerization or plaque formation. Ability to synthesize OPGs was beneficial to bacteria in order to initiate growth under low osmolarity conditions, in vitro mammalian cell invasion assays, however, could not discriminate whether OPGs were required for basic aspect of Shigella virulence. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s00203-009-0538-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Liu Liu
- College of Food Science and Technology, Northwest A&F University, 712100 Yangling, China
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36
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Osmoregulated Periplasmic Glucan Polymerization Requires Constant Protein Synthesis in Escherichia coli. Curr Microbiol 2010; 61:396-400. [DOI: 10.1007/s00284-010-9625-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 03/16/2010] [Indexed: 10/19/2022]
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Costa CS, Pizarro RA, Antón DN. Influence of RpoS, cAMP-receptor protein, and ppGpp on expression of the opgGH operon and osmoregulated periplasmic glucan content of Salmonella enterica serovar Typhimurium. Can J Microbiol 2010; 55:1284-93. [PMID: 19940937 DOI: 10.1139/w09-086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A transcriptional fusion (opgG1::MudJ) to the opgGH operon of Salmonella enterica serovar Typhimurium (S. Typhimurium) LT2, isolated by resistance to mecillinam, was used to study the influence of global regulators RpoS, ppGpp, and cAMP/cAMP-receptor protein (CRP) on expression of the opgGH operon and osmoregulated periplasmic glucan (OPG) content. Neither high growth medium osmolarity nor absence of ppGpp or CRP had important effects on opgG1::MudJ expression in exponential cultures. However, under the same conditions, OPG content was strongly decreased by high osmolarity or cAMP/CRP defectiveness, and reduced to a half by lack of ppGpp. In stationary cultures, high osmolarity as well as CRP loss caused significant descents in opgG1::MudJ expression that were compensated by inactivation of RpoS sigma factor. No effect of RpoS inactivation on OPG content was observed. It is concluded that opgGH expression in S. Typhimurium is only slightly affected by high osmolarity, but is inversely modulated by RpoS level. On the other hand, osmolarity and the cAMP/CRP global regulatory system appear to control OPG content, either directly or indirectly, mainly at the post-transcriptional level.
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Affiliation(s)
- Cristina S Costa
- Departamento de Radiobiología, Comisión Nacional de Energía Atómica, Avda. General Paz 1499, 1650 San Martín, Argentina
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Penaloza-Vazquez A, Sreedharan A, Bender CL. Transcriptional studies of the hrpM/opgH gene in Pseudomonas syringae during biofilm formation and in response to different environmental challenges. Environ Microbiol 2010; 12:1452-67. [PMID: 20132277 DOI: 10.1111/j.1462-2920.2010.02160.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Pseudomonas syringae pv. syringae strain FF5 is a phytopathogen that causes a rapid dieback on ornamental pear trees. In the present study, the transcriptional expression of hrpM/opgH, algD, hrpR and rpoD was evaluated in P. syringae FF5 and FF5.M2 (hrpM/opgH mutant). The temporal expression of these genes was evaluated during biofilm formation, the hypersensitive reaction (HR) on tobacco plants, and when the bacteria were subjected to different environmental stresses. The results indicate that mutations in hrpM negatively impair several traits including biofilm formation, the ability to cause disease in host plants and the HR in non-host plants, and the expression of hrpR, a regulatory gene modulating the latter two traits. Furthermore, FF5.M2 was decreased in swarming motility and unable to respond to different environmental challenges. Interestingly, FF5.M2 showed an exponential increase in the expression of algD, which is the first gene to be transcribed during the biosynthesis of the alginate, a virulence factor in P. syringae. The expression of both hrpM and algD were required for biofilm formation, and hrpM was expressed earlier than algD during biofilm development. These findings indicate that hrpM expression is required for several traits in P. syringae and plays an important role in how this bacterium responds to environmental challenges.
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Affiliation(s)
- Alejandro Penaloza-Vazquez
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Motility Revertants of opgGH Mutants of Salmonella enterica Serovar Typhimurium Remain Defective in Mice Virulence. Curr Microbiol 2009; 59:641-5. [DOI: 10.1007/s00284-009-9486-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 07/30/2009] [Accepted: 08/07/2009] [Indexed: 10/20/2022]
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Liu L, Tan S, Jun W, Smith A, Meng J, Bhagwat AA. Osmoregulated periplasmic glucans are needed for competitive growth and biofilm formation bySalmonella entericaserovar Typhimurium in leafy-green vegetable wash waters and colonization in mice. FEMS Microbiol Lett 2009; 292:13-20. [DOI: 10.1111/j.1574-6968.2008.01462.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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