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Kay EJ, Dooda MK, Bryant JC, Reid AJ, Wren BW, Troutman JM, Jorgenson MA. Engineering Escherichia coli for increased Und-P availability leads to material improvements in glycan expression technology. Microb Cell Fact 2024; 23:72. [PMID: 38429691 PMCID: PMC10908060 DOI: 10.1186/s12934-024-02339-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/16/2024] [Indexed: 03/03/2024] Open
Abstract
BACKGROUND Bacterial surface glycans are assembled by glycosyltransferases (GTs) that transfer sugar monomers to long-chained lipid carriers. Most bacteria employ the 55-carbon chain undecaprenyl phosphate (Und-P) to scaffold glycan assembly. The amount of Und-P available for glycan synthesis is thought to be limited by the rate of Und-P synthesis and by competition for Und-P between phosphoglycosyl transferases (PGTs) and GTs that prime glycan assembly (which we collectively refer to as PGT/GTs). While decreasing Und-P availability disrupts glycan synthesis and promotes cell death, less is known about the effects of increased Und-P availability. RESULTS To determine if cells can maintain higher Und-P levels, we first reduced intracellular competition for Und-P by deleting all known non-essential PGT/GTs in the Gram-negative bacterium Escherichia coli (hereafter called ΔPGT/GT cells). We then increased the rate of Und-P synthesis in ΔPGT/GT cells by overexpressing the Und-P(P) synthase uppS from a plasmid (puppS). Und-P quantitation revealed that ΔPGT/GT/puppS cells can be induced to maintain 3-fold more Und-P than wild type cells. Next, we determined how increasing Und-P availability affects glycan expression. Interestingly, increasing Und-P availability increased endogenous and recombinant glycan expression. In particular, ΔPGT/GT/puppS cells could be induced to express 7-fold more capsule from Streptococcus pneumoniae serotype 4 than traditional E. coli cells used to express recombinant glycans. CONCLUSIONS We demonstrate that the biotechnology standard bacterium E. coli can be engineered to maintain higher levels of Und-P. The results also strongly suggest that Und-P pathways can be engineered to increase the expression of potentially any Und-P-dependent polymer. Given that many bacterial glycans are central to the production of vaccines, diagnostics, and therapeutics, increasing Und-P availability should be a foremost consideration when designing bacterial glycan expression systems.
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Affiliation(s)
- Emily J Kay
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Manoj K Dooda
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
| | - Joseph C Bryant
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, 4301 West Markham St. / Biomed I, Room 511 / Little Rock, Little Rock, AR, 72205, USA
| | - Amanda J Reid
- Nanoscale Science Program, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
| | - Brendan W Wren
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Jerry M Troutman
- Nanoscale Science Program, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
- Department of Chemistry, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
| | - Matthew A Jorgenson
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, 4301 West Markham St. / Biomed I, Room 511 / Little Rock, Little Rock, AR, 72205, USA.
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Ascari A, Frölich S, Zang M, Tran ENH, Wilson DW, Morona R, Eijkelkamp BA. Shigella flexneri remodeling and consumption of host lipids during infection. J Bacteriol 2023; 205:e0032023. [PMID: 37991380 PMCID: PMC10729657 DOI: 10.1128/jb.00320-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/10/2023] [Indexed: 11/23/2023] Open
Abstract
IMPORTANCE Bacterial pathogens have vastly distinct sites that they inhabit during infection. This requires adaptation due to changes in nutrient availability and antimicrobial stress. The bacterial surface is a primary barrier, and here, we show that the bacterial pathogen Shigella flexneri increases its surface decorations when it transitions to an intracellular lifestyle. We also observed changes in bacterial and host cell fatty acid homeostasis. Specifically, intracellular S. flexneri increased the expression of their fatty acid degradation pathway, while the host cell lipid pool was significantly depleted. Importantly, bacterial proliferation could be inhibited by fatty acid supplementation of host cells, thereby providing novel insights into the possible link between human malnutrition and susceptibility to S. flexneri.
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Affiliation(s)
- Alice Ascari
- Department of Molecular and Biomedical Science, School of Biological Sciences, Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Adelaide, Australia
| | - Sonja Frölich
- Department of Molecular and Biomedical Science, School of Biological Sciences, Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia
- Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, Adelaide, Australia
| | - Maoge Zang
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Adelaide, Australia
| | - Elizabeth N. H. Tran
- Department of Molecular and Biomedical Science, School of Biological Sciences, Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia
| | - Danny W. Wilson
- Department of Molecular and Biomedical Science, School of Biological Sciences, Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia
- Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, Adelaide, Australia
| | - Renato Morona
- Department of Molecular and Biomedical Science, School of Biological Sciences, Research Centre for Infectious Diseases, University of Adelaide, Adelaide, Australia
| | - Bart A. Eijkelkamp
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Adelaide, Australia
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Ascari A, Waters JK, Morona R, Eijkelkamp BA. Shigella flexneri Adapts to Niche-Specific Stresses through Modifications in Cell Envelope Composition and Decoration. ACS Infect Dis 2023; 9:1610-1621. [PMID: 37494550 DOI: 10.1021/acsinfecdis.3c00210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Shigella flexneri is the primary causative agent of worldwide shigellosis. As the pathogen transverses the distinct niches of the gastrointestinal tract it necessitates dynamic adaptation strategies to mitigate host antimicrobials such as dietary fatty acids (FAs) and the bile salt, deoxycholate (DOC). This study investigates the dynamics of the S. flexneri cell envelope, by interrogating adaptations following FA or DOC exposure. We deciphered the effects of FAs and DOC on bacterial membrane fatty acid and lipopolysaccharide (LPS) compositions. We identified novel LPS-based strategies by the pathogen to support resistance to these host compounds. In particular, expression of S. flexneri very-long O antigen (VL-Oag) LPS was found to play a central role in stress mitigation, as VL-Oag protects against antimicrobial FAs, but its presence rendered S. flexneri susceptible to DOC stress. Collectively, this work underpins the importance for S. flexneri to maintain appropriate regulation of cell envelope constituents, in particular VL-Oag LPS, to adequately adapt to diverse stresses during infection.
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Affiliation(s)
- Alice Ascari
- School of Biological Sciences, Department of Molecular and Biomedical Science, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, South Australia, Australia
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Adelaide 5042, South Australia, Australia
| | - Jack K Waters
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Adelaide 5042, South Australia, Australia
| | - Renato Morona
- School of Biological Sciences, Department of Molecular and Biomedical Science, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, South Australia, Australia
| | - Bart A Eijkelkamp
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Adelaide 5042, South Australia, Australia
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4
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Identification of the Shigella flexneri Wzy Domain Modulating Wzz pHS-2 Interaction and Detection of the Wzy/Wzz/Oag Complex. J Bacteriol 2022; 204:e0022422. [PMID: 35980183 PMCID: PMC9487639 DOI: 10.1128/jb.00224-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shigella flexneri implements the Wzy-dependent pathway to biosynthesize the O antigen (Oag) component of its surface lipopolysaccharide. The inner membrane polymerase WzySF catalyzes the repeat addition of undecaprenol-diphosphate-linked Oag (Und-PP-RUs) to produce a polysaccharide, the length of which is tightly regulated by two competing copolymerase proteins, WzzSF (short-type Oag; 10 to 17 RUs) and WzzpHS-2 (very-long-type Oag; >90 RUs). The nature of the interaction between WzySF and WzzSF/WzzpHS-2 in Oag polymerization remains poorly characterized, with the majority of the literature characterizing the individual protein constituents of the Wzy-dependent pathway. Here, we report instead a major investigation into the specific binding interactions of WzySF with its copolymerase counterparts. For the first time, a region of WzySF that forms a unique binding site for WzzpHS-2 has been identified. Specifically, this work has elucidated key WzySF moieties at the N- and C-terminal domains (NTD and CTD) that form an intramolecular pocket modulating the WzzpHS-2 interaction. Novel copurification data highlight that disruption of residues within this NTD-CTD pocket impairs the interaction with WzzpHS-2 without affecting WzzSF binding, thereby specifically disrupting polymerization of longer polysaccharide chains. This study provides a novel understanding of the molecular interaction of WzySF with WzzSF/WzzpHS-2 in the Wzy-dependent pathway and, furthermore, detects the Wzy/Wzz/Und-PP-Oag complex for the first time. Beyond S. flexneri, this work may be extended to provide insight into the interactions between protein homologues expressed by related species, especially members of Enterobacteriaceae, that produce dual Oag chain length determinants. IMPORTANCE Shigella flexneri is a pathogen causing significant morbidity and mortality, predominantly devastating the pediatric age group in developing countries. A major virulence factor contributing to S. flexneri pathogenesis is its surface lipopolysaccharide, which is comprised of three domains: lipid A, core oligosaccharide, and O antigen (Oag). The Wzy-dependent pathway is the most common biosynthetic mechanism implemented for Oag biosynthesis by Gram-negative bacteria, including S. flexneri. The nature of the interaction between the polymerase, WzySF, and the polysaccharide copolymerases, WzzSF and WzzpHS-2, in Oag polymerization is poorly characterized. This study investigates the molecular interplay between WzySF and its copolymerases, deciphering key interactions in the Wzy-dependent pathway that may be extended beyond S. flexneri, providing insight into Oag biosynthesis in Gram-negative bacteria.
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Krzyżewska-Dudek E, Kotimaa J, Kapczyńska K, Rybka J, Meri S. Lipopolysaccharides and outer membrane proteins as main structures involved in complement evasion strategies of non-typhoidal Salmonella strains. Mol Immunol 2022; 150:67-77. [PMID: 35998438 DOI: 10.1016/j.molimm.2022.08.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/10/2022] [Accepted: 08/15/2022] [Indexed: 11/27/2022]
Abstract
Non-typhoidal Salmonella (NTS) infections pose a serious public health problem. In addition to the typical course of salmonellosis, an infection with Salmonella bacteria can often lead to parenteral infections and sepsis, which are particularly dangerous for children, the elderly and immunocompromised. Bacterial resistance to serum is a key virulence factor for the development of systemic infections. Salmonella, as an enterobacterial pathogen, has developed several mechanisms to escape and block the antibacterial effects of the complement system. In this review, we discuss the relevance of outer membrane polysaccharides to the complement evasion mechanisms of NTS strains. These include the influence of the overall length and density of the lipopolysaccharide molecules, modifications of the O-antigen lipopolysaccharide composition and the role of capsular polysaccharides in opsonization and protection of the outer membrane from the lytic action of complement. Additionally, we discuss specific outer membrane protein complement evasion mechanisms, such as recruitment of complement regulatory proteins, blocking assembly of late complement components to form the membrane attack complex and the proteolytic cleavage of complement proteins.
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Affiliation(s)
- E Krzyżewska-Dudek
- Department of Bacteriology and Immunology, Translational Immunology Research Program, University of Helsinki, and Diagnostic Center (HUSLAB), Helsinki University Hospital, 00290 Helsinki, Finland; Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland
| | - J Kotimaa
- Department of Bacteriology and Immunology, Translational Immunology Research Program, University of Helsinki, and Diagnostic Center (HUSLAB), Helsinki University Hospital, 00290 Helsinki, Finland
| | - K Kapczyńska
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland
| | - J Rybka
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland
| | - S Meri
- Department of Bacteriology and Immunology, Translational Immunology Research Program, University of Helsinki, and Diagnostic Center (HUSLAB), Helsinki University Hospital, 00290 Helsinki, Finland.
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Ascari A, Tran ENH, Eijkelkamp BA, Morona R. Detection of a disulphide bond and conformational changes in Shigella flexneri Wzy, and the role of cysteine residues in polymerase activity. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183871. [PMID: 35090897 DOI: 10.1016/j.bbamem.2022.183871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 01/11/2022] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
Shigella flexneri utilises the Wzy-dependent pathway for the production of a plethora of complex polysaccharides, including the lipopolysaccharide O-antigen (Oag) component. The inner membrane protein WzySF polymerises Oag repeat units, whilst two co-polymerase proteins, WzzSF and WzzpHS-2, together interact with WzySF to regulate production of short- (S-Oag) and very long- (VL-Oag) Oag modal lengths, respectively. The 2D arrangement of WzySF transmembrane and soluble regions has been previously deciphered, however, attaining information on the 3D structural and conformational arrangement of WzySF, or any homologue, has proven difficult. For the first time, the current study detected insights into the in situ WzySF arrangement. In vitro assays using thiol-reactive PEG-maleimide were used to probe WzySF conformation, which additionally detected novel, unique conformational changes in response to interaction with intrinsic factors, including WzzSF and WzzpHS-2, and extrinsic factors, such as temperature. Site-directed mutagenesis of WzySF cysteine residues revealed the presence of a putative intramolecular disulphide bond, between cysteine moieties 13 and 60. Subsequent analyses highlighted both the structural and functional importance of WzySF cysteines. Substitution of WzySF cysteine residues significantly decreased biosynthesis of the VL-Oag modal length, without disruption to S-Oag production. This phenotype was corroborated in the absence of co-polymerase competition for WzySF interaction. These data suggest WzySF cysteine substitutions directly impair the interaction between Wzy/WzzpHS-2, without altering the Wzy/WzzSF interplay, and in combination with structural data, we propose that the N- and C-termini of WzySF are arranged in close proximity, and together may form the unique WzzpHS-2 interaction site.
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Affiliation(s)
- Alice Ascari
- School of Biological Sciences, Department of Molecular and Biomedical Science, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, Australia.
| | - Elizabeth Ngoc Hoa Tran
- School of Biological Sciences, Department of Molecular and Biomedical Science, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, Australia.
| | - Bart A Eijkelkamp
- Molecular Sciences and Technology, College of Science and Engineering, Flinders University, Adelaide 5042, South Australia, Australia.
| | - Renato Morona
- School of Biological Sciences, Department of Molecular and Biomedical Science, Research Centre for Infectious Diseases, University of Adelaide, Adelaide 5005, Australia.
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7
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Identification of a Region in Shigella flexneri WzyB Disrupting the Interaction with Wzz pHS2. J Bacteriol 2021; 203:e0041321. [PMID: 34491798 DOI: 10.1128/jb.00413-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Shigella flexneri can synthesize polysaccharide chains having complex sugars and a regulated number of repeating units. S. flexneri lipopolysaccharide O antigen (Oag) is synthesized by the Wzy-dependent pathway, which is the most common pathway used in bacteria for polysaccharide synthesis. The inner membrane protein WzyB polymerizes the Oag repeat units into chains, while the polysaccharide copolymerases WzzB and WzzpHS2 determine the average number of repeat units or "the modal length," termed short type and very long type. Our data show for the first time a direct interaction between WzyB and WzzpHS2, with and without the use of the chemical cross-linker dithiobis (succinimidyl propionate) (DSP). Additionally, mutations generated via random and site-directed mutagenesis identify a region of WzyB that caused diminished function and significantly decreased very long Oag chain polymerization, and that affected the aforementioned interaction. These results provide insight into the mechanisms underlying the regulation of Oag biosynthesis. IMPORTANCE Complex polysaccharide chains are synthesized by bacteria, usually at a regulated number of repeating units, which has broad implications for bacterial pathogenesis. One example is the O antigen (Oag) component of lipopolysaccharide that is predominantly synthesized by the Wzy-dependent pathway. Our findings show for the first time a direct physical interaction between WzyB and WzzpHS2. Additionally, a set of Wzy mutant constructs were generated, revealing a proposed active site/switch region involved in the activity of WzyB and the physical interaction with WzzpHS2. Combined, these findings further understanding of the Wzy-dependent pathway. The identification of a novel interaction with the polysaccharide copolymerase WzzpHS2 and the region of WzyB that is involved in this aforementioned interaction and its impact on WzyB Oag synthesis activity have significant implication for the prevention/treatment of bacterial diseases and discovery of novel biotechnologies.
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Mancini F, Gasperini G, Rossi O, Aruta MG, Raso MM, Alfini R, Biagini M, Necchi F, Micoli F. Dissecting the contribution of O-Antigen and proteins to the immunogenicity of Shigella sonnei generalized modules for membrane antigens (GMMA). Sci Rep 2021; 11:906. [PMID: 33441861 PMCID: PMC7806729 DOI: 10.1038/s41598-020-80421-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 12/11/2020] [Indexed: 01/11/2023] Open
Abstract
GMMA are exosomes released from engineered Gram-negative bacteria resembling the composition of outer membranes. We applied the GMMA technology for the development of an O-Antigen (OAg) based vaccine against Shigella sonnei, the most epidemiologically relevant cause of shigellosis. S. sonnei OAg has been identified as a key antigen for protective immunity, and GMMA are able to induce anti-OAg-specific IgG response in animal models and healthy adults. The contribution of protein-specific antibodies induced upon vaccination with GMMA has never been fully elucidated. Anti-protein antibodies are induced in mice upon immunization with either OAg-negative and OAg-positive GMMA. Here we demonstrated that OAg chains shield the bacteria from anti-protein antibody binding and therefore anti-OAg antibodies were the main drivers of bactericidal activity against OAg-positive bacteria. Interestingly, antibodies that are not targeting the OAg are functional against OAg-negative bacteria. The immunodominant protein antigens were identified by proteomic analysis. Our study confirms a critical role of the OAg on the immune response induced by S. sonnei GMMA. However, little is known about OAg length and density regulation during infection and, therefore, protein exposure. Hence, the presence of protein antigens on S. sonnei GMMA represents an added value for GMMA vaccines compared to other OAg-based formulations.
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Affiliation(s)
- Francesca Mancini
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Gianmarco Gasperini
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Omar Rossi
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Maria Grazia Aruta
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Maria Michelina Raso
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Renzo Alfini
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | | | - Francesca Necchi
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Francesca Micoli
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy.
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9
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Leo V, Tran E, Morona R. Polysaccharide co-polymerase WzzB/WzzE chimeras reveal transmembrane 2 region of WzzB is important for interaction with WzyB. J Bacteriol 2020; 203:JB.00598-20. [PMID: 33361196 PMCID: PMC8095455 DOI: 10.1128/jb.00598-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 12/03/2020] [Indexed: 12/13/2022] Open
Abstract
The ability of bacteria to synthesise complex polysaccharide chains at a controlled number of repeating units has wide implications for a range of biological activities that include: symbiosis, biofilm formation and immune system avoidance. Complex polysaccharide chains such as the O antigen (Oag) component of lipopolysaccharide and the enterobacterial common antigen (ECA) are synthesised by the most common polysaccharide synthesis pathway used in bacteria, known as the Wzy-dependent pathway. The Oag and ECA are polymerized into chains via the inner membrane proteins WzyB and WzyE, respectively, while the respective co-polymerases WzzB and WzzE modulate the number of repeat units in the chains or "the modal length" of the polysaccharide via a hypothesised interaction. Our data shows for the first time "cross-talk" between Oag and ECA synthesis in that WzzE is able to partially regulate Oag modal length via a potential interaction with WzyB. To investigate this, one or both of the transmembrane regions (TM1 and TM2) of WzzE and WzzB were swapped creating six chimera proteins. Several chimeric proteins showed significant increases Oag modal length control, while others reduced control. Additionally, co-purification experiments show an interaction between WzyB and WzzB for the first time without the use of a chemical cross-linker, and a novel interaction between WzyB and WzzE. These results suggest the TM2 region of Wzz proteins plays a critical role in Oag and ECA modal length control, presumably via the interaction with respective Wzy proteins, thus providing insight into the complex mechanism underlying the control of polysaccharide biosynthesis.ImportanceBacteria synthesise complex polysaccharide chains at a controlled number of repeating units, this has wide implications for a range of bacterial activities involved in virulence. Examples of complex polysaccharide chains include, the O antigen (Oag) component of lipopolysaccharide and the enterobacterial common antigen (ECA), both of these examples are predominantly synthesised by their own independent Wzy-dependent pathway. Our data show for the first time "cross-talk" between Oag and ECA synthesis and identifies novel physical protein-protein interactions between proteins in these systems. These findings further the understanding of how the system functions to control polysaccharide chain length which has great implications for novel biotechnologies and/or the combat of bacterial diseases.
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Affiliation(s)
- Vincenzo Leo
- Department of Molecular and Biomedical Science, School of Biological Sciences, Research Centre for Infectious Diseases, The University of Adelaide, Adelaide, SA, Australia
| | - Elizabeth Tran
- Department of Molecular and Biomedical Science, School of Biological Sciences, Research Centre for Infectious Diseases, The University of Adelaide, Adelaide, SA, Australia
| | - Renato Morona
- Department of Molecular and Biomedical Science, School of Biological Sciences, Research Centre for Infectious Diseases, The University of Adelaide, Adelaide, SA, Australia.
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10
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Whitfield C, Williams DM, Kelly SD. Lipopolysaccharide O-antigens-bacterial glycans made to measure. J Biol Chem 2020; 295:10593-10609. [PMID: 32424042 DOI: 10.1074/jbc.rev120.009402] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/17/2020] [Indexed: 01/05/2023] Open
Abstract
Lipopolysaccharides are critical components of bacterial outer membranes. The more conserved lipid A part of the lipopolysaccharide molecule is a major element in the permeability barrier imposed by the outer membrane and offers a pathogen-associated molecular pattern recognized by innate immune systems. In contrast, the long-chain O-antigen polysaccharide (O-PS) shows remarkable structural diversity and fulfills a range of functions, depending on bacterial lifestyles. O-PS production is vital for the success of clinically important Gram-negative pathogens. The biological properties and functions of O-PSs are mostly independent of specific structures, but the size distribution of O-PS chains is particularly important in many contexts. Despite the vast O-PS chemical diversity, most are produced in bacterial cells by two assembly strategies, and the different mechanisms employed in these pathways to regulate chain-length distribution are emerging. Here, we review our current understanding of the mechanisms involved in regulating O-PS chain-length distribution and discuss their impact on microbial cell biology.
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Affiliation(s)
- Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Danielle M Williams
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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Yang J, Zhang N, Lv J, Zhu P, Pan X, Hu J, Wu W, Li S, Li H. Comparing the performance of conventional PCR, RTQ-PCR, and droplet digital PCR assays in detection of Shigella. Mol Cell Probes 2020; 51:101531. [PMID: 32062018 DOI: 10.1016/j.mcp.2020.101531] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/19/2020] [Accepted: 02/06/2020] [Indexed: 12/15/2022]
Abstract
The incidence of foodborne infections caused by Shigella spp. is still very high in every year, which poses a great potential threat to public health. Conventional quantification methods based on culture techniques, biochemical, and serological identification are time-consuming and labor-intensive. To develop a more rapid and efficient detection method of Shigella spp., we compared the sensitivity and specificity of three different polymerase chain reaction (PCR) methods, including conventional PCR, quantitative real-time PCR (RTQ-PCR), and droplet digital PCR (ddPCR). Our results indicated that ddPCR method exhibited higher sensitivity, and the limit of detection was 10-5 ng/μl for genomic DNA templates, 10-1 cfu/ml for Shigella bacteria culture. In addition, we found that ddPCR was a time-saving method, which required a shorter pre-culturing time. Collectively, ddPCR assay was a reliable method for rapid and effective detection of Shigella spp.
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Affiliation(s)
- Jin Yang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China.
| | - Nana Zhang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China.
| | - Jun Lv
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.
| | - Ping Zhu
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.
| | - Xing Pan
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.
| | - Jiaqingzi Hu
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.
| | - Wenfeng Wu
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China.
| | - Shan Li
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, 442000, China.
| | - Hongtao Li
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Beibei, 400715, Chongqing, China.
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12
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Kim MJ, Moon YH, Kim H, Rho S, Shin YK, Song M, Walker R, Czerkinsky C, Kim DW, Kim JO. Cross-Protective Shigella Whole-Cell Vaccine With a Truncated O-Polysaccharide Chain. Front Microbiol 2018; 9:2609. [PMID: 30429838 PMCID: PMC6220597 DOI: 10.3389/fmicb.2018.02609] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 10/12/2018] [Indexed: 11/13/2022] Open
Abstract
Shigella is a highly prevalent bacterium causing acute diarrhea and dysentery in developing countries. Shigella infections are treated with antibiotics but Shigellae are increasingly resistant to these drugs. Vaccination can be a countermeasure against emerging antibiotic-resistant shigellosis. Because of the structural variability in Shigellae O-antigen polysaccharides (Oag), cross-protective Shigella vaccines cannot be derived from single serotype-specific Oag. We created an attenuated Shigella flexneri 2a strain with one rather than multiple Oag units by disrupting the Oag polymerase gene (Δwzy), which broadened protective immunogenicity by exposing conserved surface proteins. Inactivated Δwzy mutant cells combined with Escherichia coli double mutant LT(R192G/L211A) as adjuvant, induced potent antibody responses to outer membrane protein PSSP-1, and type III secretion system proteins IpaB and IpaC. Intranasal immunization with the vaccine preparation elicited cross-protective immunity against S. flexneri 2a, S. flexneri 3a, S. flexneri 6, and Shigella sonnei in a mouse pneumonia model. Thus, S. flexneri 2a Δwzy represents a promising candidate strain for a universal Shigella vaccine.
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Affiliation(s)
- Min Jung Kim
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea.,Laboratory of Molecular Pathology and Cancer Genomics, College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Young-Hye Moon
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | - Heejoo Kim
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | - Semi Rho
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | - Young Kee Shin
- Laboratory of Molecular Pathology and Cancer Genomics, College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Manki Song
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | | | - Cecil Czerkinsky
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea.,Institut de Pharmacologie Moléculaire & Cellulaire CNRS-INSERM-University of Nice Sophia Antipolis, Valbonne, France
| | - Dong Wook Kim
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | - Jae-Ouk Kim
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
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13
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Novel Role of VisP and the Wzz System during O-Antigen Assembly in Salmonella enterica Serovar Typhimurium Pathogenesis. Infect Immun 2018; 86:IAI.00319-18. [PMID: 29866904 DOI: 10.1128/iai.00319-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 05/14/2018] [Indexed: 01/18/2023] Open
Abstract
Salmonella enterica serovars are associated with diarrhea and gastroenteritis and are a helpful model for understanding host-pathogen mechanisms. Salmonella enterica serovar Typhimurium regulates the distribution of O antigen (OAg) and presents a trimodal distribution based on Wzy polymerase and the WzzST (long-chain-length OAg [L-OAg]) and WzzfepE (very-long-chain-length OAg [VL-OAg]) copolymerases; however, several mechanisms regulating this process remain unclear. Here, we report that LPS modifications modulate the infectious process and that OAg chain length determination plays an essential role during infection. An increase in VL-OAg is dependent on Wzy polymerase, which is promoted by a growth condition resembling the environment of Salmonella-containing vacuoles (SCVs). The virulence- and stress-related periplasmic protein (VisP) participates in OAg synthesis, as a ΔvisP mutant presents a semirough OAg phenotype. The ΔvisP mutant has greatly decreased motility and J774 macrophage survival in a colitis model of infection. Interestingly, the phenotype is restored after mutation of the wzzST or wzzfepE gene in a ΔvisP background. Loss of both the visP and wzzST genes promotes an imbalance in flagellin secretion. L-OAg may function as a shield against host immune systems in the beginning of an infectious process, and VL-OAg protects bacteria during SCV maturation and facilitates intramacrophage replication. Taken together, these data highlight the roles of OAg length in generating phenotypes during S Typhimurium pathogenesis and show the periplasmic protein VisP as a novel protein in the OAg biosynthesis pathway.
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14
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Hegerle N, Bose J, Ramachandran G, Galen JE, Levine MM, Simon R, Tennant SM. Overexpression of O-polysaccharide chain length regulators in Gram-negative bacteria using the Wzx-/Wzy-dependent pathway enhances production of defined modal length O-polysaccharide polymers for use as haptens in glycoconjugate vaccines. J Appl Microbiol 2018; 125:575-585. [PMID: 29603538 PMCID: PMC6726474 DOI: 10.1111/jam.13772] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/20/2017] [Accepted: 03/26/2018] [Indexed: 11/30/2022]
Abstract
Aims O‐polysaccharide (OPS) molecules are protective antigens for several bacterial pathogens, and have broad utility as components of glycoconjugate vaccines. Variability in the OPS chain length is one obstacle towards further development of these vaccines. Introduction of sizing steps during purification of OPS molecules of suboptimal or of mixed lengths introduces additional costs and complexity while decreasing the final yield. The overall goal of this study was to demonstrate the utility of engineering Gram‐negative bacteria to produce homogenous O‐polysaccharide populations that can be used as the basis of carbohydrate vaccines by overexpressing O‐polysaccharide chain length regulators of the Wzx‐/Wzy‐dependent pathway. Method and Results The O‐polysaccharide chain length regulators wzzB and fepE from Salmonella Typhimurium I77 and wzz2 from Pseudomonas aeruginosa PAO1 were cloned and expressed in the homologous organism or in other Gram‐negative bacteria. Overexpression of these Wzz proteins in the homologous organism significantly increased the proportion of long or very long chain O‐polysaccharides. The same observation was made when wzzB was overexpressed in Salmonella Paratyphi A and Shigella flexneri, and wzz2 was overexpressed in two other strains of P. aeruginosa. Conclusions Overexpression of Wzz proteins in Gram‐negative bacteria using the Wzx/Wzy‐dependant pathway for lipopolysaccharide synthesis provides a genetic method to increase the production of an O‐polysaccharide population of a defined size. Significance and Impact of the Study The methods presented herein represent a cost‐effective and improved strategy for isolating preferred OPS vaccine haptens, and could facilitate the further use of O‐polysaccharides in glycoconjugate vaccine development.
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Affiliation(s)
- N Hegerle
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - J Bose
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - G Ramachandran
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - J E Galen
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - M M Levine
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - R Simon
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - S M Tennant
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
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15
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Marczak M, Mazur A, Koper P, Żebracki K, Skorupska A. Synthesis of Rhizobial Exopolysaccharides and Their Importance for Symbiosis with Legume Plants. Genes (Basel) 2017; 8:E360. [PMID: 29194398 PMCID: PMC5748678 DOI: 10.3390/genes8120360] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/26/2017] [Accepted: 11/29/2017] [Indexed: 12/25/2022] Open
Abstract
Rhizobia dwell and multiply in the soil and represent a unique group of bacteria able to enter into a symbiotic interaction with plants from the Fabaceae family and fix atmospheric nitrogen inside de novo created plant organs, called nodules. One of the key determinants of the successful interaction between these bacteria and plants are exopolysaccharides, which represent species-specific homo- and heteropolymers of different carbohydrate units frequently decorated by non-carbohydrate substituents. Exopolysaccharides are typically built from repeat units assembled by the Wzx/Wzy-dependent pathway, where individual subunits are synthesized in conjunction with the lipid anchor undecaprenylphosphate (und-PP), due to the activity of glycosyltransferases. Complete oligosaccharide repeat units are transferred to the periplasmic space by the activity of the Wzx flippase, and, while still being anchored in the membrane, they are joined by the polymerase Wzy. Here we have focused on the genetic control over the process of exopolysaccharides (EPS) biosynthesis in rhizobia, with emphasis put on the recent advancements in understanding the mode of action of the key proteins operating in the pathway. A role played by exopolysaccharide in Rhizobium-legume symbiosis, including recent data confirming the signaling function of EPS, is also discussed.
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Affiliation(s)
- Małgorzata Marczak
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Andrzej Mazur
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Piotr Koper
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Kamil Żebracki
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Anna Skorupska
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
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16
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Silva-Valenzuela CA, Velásquez F, Peñailillo J, Garcias-Papayani H, Fernández P, Tobar P, Contreras I, Santiviago CA, Álvarez SA. O-antigen chain-length distribution in Salmonella enterica serovar Enteritidis is regulated by oxygen availability. Biochem Biophys Res Commun 2016; 477:563-567. [PMID: 27343553 DOI: 10.1016/j.bbrc.2016.06.074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 06/15/2016] [Indexed: 10/21/2022]
Abstract
Lipopolysaccharide (LPS) consists of three covalently linked domains: the lipid A, the core region and the O antigen (OAg), consisting of repeats of an oligosaccharide. Salmonella enterica serovar Enteritidis (S. Enteritidis) produces a LPS with two OAg preferred chain lengths: a long (L)-OAg controlled by WzzSE and a very long (VL)-OAg controlled by WzzfepE. In this work, we show that OAg produced by S. Enteritidis grown in E minimal medium also presented two preferred chain-lengths. However, a simultaneous and opposing change in the production of L-OAg and VL-OAg was observed in response to oxygen availability. Biochemical and genetics analyses indicate that this process is regulated by transcriptional factors Fnr and ArcA by means of controlling the transcription of genes encoding WzzSE and WzzfepE in response to oxygen availability. Thus, our results revealed a sophisticated regulatory mechanism involved in the adaptation of S. Enteritidis to one of the main environmental cues faced by this pathogen during infection.
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Affiliation(s)
- Cecilia A Silva-Valenzuela
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile; Department of Molecular Biology and Microbiology, Tufts University, Boston, MA, USA
| | - Felipe Velásquez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Johany Peñailillo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Héctor Garcias-Papayani
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Paulina Fernández
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Pía Tobar
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Inés Contreras
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Carlos A Santiviago
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Sergio A Álvarez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
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17
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Nath P, Morona R. Detection of Wzy/Wzz interaction in Shigella flexneri. MICROBIOLOGY-SGM 2015; 161:1797-1805. [PMID: 26296569 DOI: 10.1099/mic.0.000132] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The O antigen (Oag) component of Shigella flexneri lipopolysaccharide (LPS) is important for virulence and a protective antigen. It is synthesized by the Wzy-dependent mechanism. S. flexneri Wzy has 12 transmembrane segments and two large periplasmic loops. The modal chain length of the Oag is determined by Wzz. Experimental evidence supports multi-protein interactions in the Wzy-dependent pathway. However, evidence for direct interaction of Wzy with the other proteins of the Wzy-dependent pathway is limited. Initially, we purified Wzy-GFP-His8 and detected the presence of a dimeric form. In vivo cross-linking was then performed in an S. flexneri wzy mutant strain carrying plasmids encoding Wzy-GFP-His8 and untagged Wzz. Following solubilization with n-dodecyl-β-D-maltopyranoside (DDM) and affinity purification of Wzy-GFP-His8, Western immunoblotting with Wzz antibody detected co-purification of Wzz; this was supported by MS analysis. To the best of our knowledge, this is the first reported isolation of a complex between Wzy and Wzz. Wzy mutants (WzyR164A, WzyV92M, WzyY137H, and WzyR250K) whose properties are affected by Wzz were able to form complexes with Wzz. Their mutational alterations did not affect the interaction of Wzy with Wzz. Thus, the interaction may involve many regions of Wzy.
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Affiliation(s)
- Pratiti Nath
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide 5005, Australia
| | - Renato Morona
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide 5005, Australia
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18
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Shigella outer membrane protein PSSP-1 is broadly protective against Shigella infection. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 22:381-8. [PMID: 25651919 DOI: 10.1128/cvi.00661-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In developing countries, Shigella is a primary cause of diarrhea in infants and young children. Although antibiotic therapy is an effective treatment for shigellosis, therapeutic options are narrowing due to the emergence of antibiotic resistance. Thus, preventive vaccination could become the most efficacious approach for controlling shigellosis. We have identified several conserved protein antigens that are shared by multiple Shigella serotypes and species. Among these, one antigen induced cross-protection against experimental shigellosis, and we have named it pan-Shigella surface protein 1 (PSSP-1). PSSP-1-induced protection requires a mucosal administration route and coadministration of an adjuvant. When PSSP-1 was administered intranasally, it induced cross-protection against Shigella flexneri serotypes 2a, 5a, and 6, Shigella boydii, Shigella sonnei, and Shigella dysenteriae serotype 1. Intradermally administered PSSP-1 induced strong serum antibody responses but failed to induce protection in the mouse lung pneumonia model. In contrast, intranasal administration elicited efficient local and systemic antibody responses and production of interleukin 17A and gamma interferon. Interestingly, blood samples from patients with recent-onset shigellosis showed variable but significant mucosal antibody responses to other conserved Shigella protein antigens but not to PSSP-1. We suggest that PSSP-1 is a promising antigen for a broadly protective vaccine against Shigella.
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19
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Islam ST, Lam JS. Synthesis of bacterial polysaccharides via the Wzx/Wzy-dependent pathway. Can J Microbiol 2014; 60:697-716. [DOI: 10.1139/cjm-2014-0595] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The surfaces of bacteria mediate a multitude of functions in the environment and in an infected host, including adhesion to both biotic and abiotic substrata, motility, immune system interaction and (or) activation, biofilm formation, and cell–cell communication, with many of these features directly influenced by cell-surface glycans. In both Gram-negative and Gram-positive bacteria, the majority of cell-surface polysaccharides are produced via the Wzx/Wzy-dependent assembly pathway; these glycans include heteropolymeric O-antigen, enterobacterial common antigen, exopolysaccharide, spore coat, and capsule in diverse bacteria. The key components of this assembly pathway are the integral inner membrane Wzx flippase, Wzy polymerase, and Wzz chain-length regulator proteins, which until recently have resisted detailed structural and functional characterization. In this review, we have provided a comprehensive synthesis of the latest structural and mechanistic data for each protein, as well as an examination of substrate specificity for each assembly step and complex formation between the constituent proteins. To complement the unprecedented explosion of genomic-sequencing data for bacteria, we have also highlighted both classical and state-of-the-art methods by which encoded Wzx, Wzy, and Wzz proteins can be reliably identified and annotated, using the model Gram-negative bacterium Pseudomonas aeruginosa as an example data set. Lastly, we outline future avenues of research, with the aim of stimulating researchers to take the next steps in investigating the function of, and interplay between, the constituents of this widespread assembly scheme.
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Affiliation(s)
- Salim T. Islam
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Joseph S. Lam
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
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20
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Mutational analysis of the Shigella flexneri O-antigen polymerase Wzy: identification of Wzz-dependent Wzy mutants. J Bacteriol 2014; 197:108-19. [PMID: 25313393 DOI: 10.1128/jb.01885-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The O-antigen (Oag) component of lipopolysaccharide (LPS) is a major virulence determinant of Shigella flexneri and is synthesized by the O-antigen polymerase, WzySf. Oag chain length is regulated by chromosomally encoded WzzSf and pHS-2 plasmid-encoded WzzpHS2. To identify functionally important amino acid residues in WzySf, random mutagenesis was performed on the wzySf gene in a pWaldo-TEV-GFP plasmid, followed by screening with colicin E2. Analysis of the LPS conferred by mutated WzySf proteins in the wzySf-deficient (Δwzy) strain identified 4 different mutant classes, with mutations found in periplasmic loop 1 (PL1), PL2, PL3, and PL6, transmembrane region 2 (TM2), TM4, TM5, TM7, TM8, and TM9, and cytoplasmic loop 1 (CL1) and CL5. The association of WzySf and WzzSf was investigated by transforming these mutated wzySf plasmids into a wzySf- and wzzSf-deficient (Δwzy Δwzz) strain. Comparison of the LPS profiles in the Δwzy and Δwzy Δwzz backgrounds identified WzySf mutants whose polymerization activities were WzzSf dependent. Colicin E2 and bacteriophage Sf6c sensitivities were consistent with the LPS profiles. Analysis of the expression levels of the WzySf-GFP mutants in the Δwzy and Δwzy Δwzz backgrounds identified a role for WzzSf in WzySf stability. Hence, in addition to its role in regulating Oag modal chain length, WzzSf also affects WzySf activity and stability.
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21
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PssP2 is a polysaccharide co-polymerase involved in exopolysaccharide chain-length determination in Rhizobium leguminosarum. PLoS One 2014; 9:e109106. [PMID: 25268738 PMCID: PMC4182512 DOI: 10.1371/journal.pone.0109106] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 09/02/2014] [Indexed: 12/16/2022] Open
Abstract
Production of extracellular polysaccharides is a complex process engaging proteins localized in different subcellular compartments, yet communicating with each other or even directly interacting in multicomponent complexes. Proteins involved in polymerization and transport of exopolysaccharide (EPS) in Rhizobium leguminosarum are encoded within the chromosomal Pss-I cluster. However, genes implicated in polysaccharide synthesis are common in rhizobia, with several homologues of pss genes identified in other regions of the R. leguminosarum genome. One such region is chromosomally located Pss-II encoding proteins homologous to known components of the Wzx/Wzy-dependent polysaccharide synthesis and transport systems. The pssP2 gene encodes a protein similar to polysaccharide co-polymerases involved in determination of the length of polysaccharide chains in capsule and O-antigen biosynthesis. In this work, a mutant with a disrupted pssP2 gene was constructed and its capabilities to produce EPS and enter into a symbiotic relationship with clover were studied. The pssP2 mutant, while not altered in lipopolysaccharide (LPS), displayed changes in molecular mass distribution profile of EPS. Lack of the full-length PssP2 protein resulted in a reduction of high molecular weight EPS, yet polymerized to a longer length than in the RtTA1 wild type. The mutant strain was also more efficient in symbiotic performance. The functional interrelation between PssP2 and proteins encoded within the Pss-I region was further supported by data from bacterial two-hybrid assays providing evidence for PssP2 interactions with PssT polymerase, as well as glycosyltransferase PssC. A possible role for PssP2 in a complex involved in EPS chain-length determination is discussed.
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22
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Kalynych S, Morona R, Cygler M. Progress in understanding the assembly process of bacterial O-antigen. FEMS Microbiol Rev 2014; 38:1048-65. [DOI: 10.1111/1574-6976.12070] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 01/28/2014] [Accepted: 02/24/2014] [Indexed: 12/20/2022] Open
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23
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Diversity of o-antigen repeat unit structures can account for the substantial sequence variation of wzx translocases. J Bacteriol 2014; 196:1713-22. [PMID: 24532778 DOI: 10.1128/jb.01323-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The most common system for synthesis of cell surface polysaccharides is the Wzx/Wzy-dependent pathway, which involves synthesis, on the cytoplasmic face of the cell membrane, of repeat units, which are then translocated to the periplasmic face by a Wzx translocase and then polymerized by Wzy to generate the polysaccharide. One such polysaccharide is O antigen, which is incorporated into lipopolysaccharide (LPS). The O antigen is extremely variable, with over 186 forms in Escherichia coli. Wzx proteins are also very diverse, but they have been thought to be specific only for the first sugar of the repeat units. However, recent studies demonstrated examples in which Wzx translocases have considerable preference for their native repeat unit, showing that specificity can extend well beyond the first sugar. These results appear to be in conflict with the early conclusions, but they involved specificity for side branch residues and could be a special case. Here we take six Wzx translocases that were critical in the earlier studies on the importance of the first sugar and assess their ability to translocate the Escherichia coli O16 and O111 repeat units. We use gene replacements to optimize maintenance of expression level and show that under these conditions the native translocases are the most effective for their native repeat unit, being, respectively, 64-fold and 4-fold more effective than the next best. We conclude that Wzx translocases are commonly adapted to their native repeat unit, which provides an explanation for the great diversity of wzx genes.
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24
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Conserved-residue mutations in Wzy affect O-antigen polymerization and Wzz-mediated chain-length regulation in Pseudomonas aeruginosa PAO1. Sci Rep 2013; 3:3441. [PMID: 24309320 PMCID: PMC3854497 DOI: 10.1038/srep03441] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 11/20/2013] [Indexed: 12/15/2022] Open
Abstract
O antigen (O-Ag) in many bacteria is synthesized via the Wzx/Wzy-dependent pathway in which Wzy polymerizes lipid-linked O-Ag subunits to modal lengths regulated by Wzz. Characterization of 83 site-directed mutants of Wzy from Pseudomonas aeruginosa PAO1 (WzyPa) in topologically-mapped periplasmic (PL) and cytoplasmic loops (CL) verified the functional importance of PL3 and PL5, with the former shown to require overall cationic properties. Essential Arg residues in the RX10G motifs of PL3 and PL5 were found to be conserved in putative homologues of WzyPa, as was the overall sequence homology between these two periplasmic loops in each protein. Amino acid substitutions in CL6 were found to alter Wzz-mediated O-antigen modality, with evidence suggesting that these changes may perturb the C-terminal WzyPa tertiary structure. Together, these data suggest that the catch-and-release mechanism of O-Ag polymerization is widespread among bacteria and that regulation of polymer length is affected by interaction of Wzz with Wzy.
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25
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Kenyon JJ, Reeves PR. The Wzy O-antigen polymerase of Yersinia pseudotuberculosis O:2a has a dependence on the Wzz chain-length determinant for efficient polymerization. FEMS Microbiol Lett 2013; 349:163-70. [PMID: 24164168 DOI: 10.1111/1574-6968.12311] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/18/2013] [Accepted: 10/18/2013] [Indexed: 11/29/2022] Open
Abstract
Lipopolysaccharide is a major immunogenic structure for the pathogen Yersinia pseudotuberculosis, which contains the O-specific polysaccharide (OPS) that is presented on the cell surface. The OPS contains many repeats of the oligosaccharide O-unit and exhibits a preferred modal chain length that has been shown to be crucial for cell protection in Yersinia. It is well established that the Wzz protein determines the preferred chain length of the OPS, and in its absence, the polymerization of O units by the Wzy polymerase is uncontrolled. However, for Y. pseudotuberculosis, a wzz mutation has never been described. In this study, we examine the effect of Wzz loss in Y. pseudotuberculosis serotype O:2a and compare the lipopolysaccharide chain-length profile to that of Escherichia coli serotype O111. In the absence of Wzz, the lipopolysaccharides of the two species showed significant differences in Wzy polymerization. Yersinia pseudotuberculosis O:2a exhibited only OPS with very short chain lengths, which is atypical of wzz-mutant phenotypes that have been observed for other species. We hypothesise that the Wzy polymerase of Y. pseudotuberculosis O:2a has a unique default activity in the absence of the Wzz, revealing the requirement of Wzz to drive O-unit polymerization to greater lengths.
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Affiliation(s)
- Johanna J Kenyon
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW, Australia
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The D3 bacteriophage α-polymerase inhibitor (Iap) peptide disrupts O-antigen biosynthesis through mimicry of the chain length regulator Wzz in Pseudomonas aeruginosa. J Bacteriol 2013; 195:4735-41. [PMID: 23955007 DOI: 10.1128/jb.00903-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Lysogenic bacteriophage D3 causes seroconversion of Pseudomonas aeruginosa PAO1 from serotype O5 to O16 by inverting the linkage between O-specific antigen (OSA) repeat units from α to β. The OSA units are polymerized by Wzy to modal lengths regulated by Wzz1 and Wzz2. A key component of the D3 seroconversion machinery is the inhibitor of α-polymerase (Iap) peptide, which is able to solely suppress α-linked long-chain OSA production in P. aeruginosa PAO1. To establish the target specificity of Iap for Wzyα, changes in OSA phenotypes were examined via Western immunoblotting for wzz1 and wzz2 single-knockout strains, as well as a wzz1 wzz2 double knockout, following the expression of iap from a tuneable vector. Increased induction of Iap expression completely abrogated OSA production in the wzz1 wzz2 double mutant, while background levels of OSA production were still observed in either of the single mutants. Therefore, Iap inhibition of OSA biosynthesis was most effective in the absence of both Wzz proteins. Sequence alignment analyses revealed a high degree of similarity between Iap and the first transmembrane segment (TMS) of either Wzz1 or Wzz2. Various topology prediction analyses of the Iap sequence consistently predicted the presence of a single TMS, suggesting a propensity for Iap to insert itself into the inner membrane (IM). The compromised ability of Iap to abrogate Wzyα function in the presence of Wzz1 or Wzz2 provides compelling evidence that inhibition occurs after Wzyα inserts itself into the IM and is achieved through mimicry of the first TMS from the Wzz proteins of P. aeruginosa PAO1.
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Kalynych S, Valvano MA, Cygler M. Polysaccharide co-polymerases: the enigmatic conductors of the O-antigen assembly orchestra. Protein Eng Des Sel 2012; 25:797-802. [PMID: 23100544 DOI: 10.1093/protein/gzs075] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The O-antigen lipopolysaccharides on bacterial surface contain variable number of oligosaccharide repeat units with their length having a modal distribution specific to the bacterial strain. The polysaccharide length distribution is controlled by the proteins called polysaccharide co-polymerases (PCPs), which are embedded in the inner membrane in Gram-negative bacteria and form homo oligomers. The 3D structures of periplasmic domains of several PCPs have been determined and provided the first insights into the possible mechanism of polysaccharide length determination mechanism. Here we review the current knowledge of structure and function of these polysaccharide length regulators.
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Affiliation(s)
- Sergei Kalynych
- Department of Biochemistry, McGill University, Montreal, Quebec H3G0B1, Canada
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Galván EM, Ielmini MV, Patel YN, Bianco MI, Franceschini EA, Schneider JC, Ielpi L. Xanthan chain length is modulated by increasing the availability of the polysaccharide copolymerase protein GumC and the outer membrane polysaccharide export protein GumB. Glycobiology 2012; 23:259-72. [DOI: 10.1093/glycob/cws146] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Contribution of the lipopolysaccharide to resistance of Shigella flexneri 2a to extreme acidity. PLoS One 2011; 6:e25557. [PMID: 21984920 PMCID: PMC3184986 DOI: 10.1371/journal.pone.0025557] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 09/07/2011] [Indexed: 11/19/2022] Open
Abstract
Shigella flexneri is endemic in most underdeveloped countries, causing diarrheal disease and dysentery among young children. In order to reach its target site, the colon, Shigella must overcome the acid environment of the stomach. Shigella is able to persist in this stressful environment and, because of this ability it can initiate infection following the ingestion of very small inocula. Thus, acid resistance is considered an important virulence trait of this bacterium. It has been reported that moderate acid conditions regulate the expression of numerous components of the bacterial envelope. Because the lipopolysaccharide (LPS) is the major component of the bacterial surface, here we have addressed the role of LPS in acid resistance of S. flexneri 2a. Defined deletion mutants in genes encoding proteins involved in the synthesis, assembly and length regulation of the LPS O antigen were constructed and assayed for resistance to pH 2.5 after adaptation to pH 5.5. The results showed that a mutant lacking O antigen was significantly more sensitive to extreme acid conditions than the wild type. Not only the presence of polymerized O antigen, but also a particular polymer length (S-OAg) was required for acid resistance. Glucosylation of the O antigen also contributed to this property. In addition, a moderate acidic pH induced changes in the composition of the lipid A domain of LPS. The main modification was the addition of phosphoethanolamine to the 1' phosphate of lipid A. This modification increased resistance of S. flexneri to extreme acid conditions, provide that O antigen was produced. Overall, the results of this work point out to an important role of LPS in resistance of Shigella flexneri to acid stress.
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