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Simpson BW, Trent MS. Pushing the envelope: LPS modifications and their consequences. Nat Rev Microbiol 2020; 17:403-416. [PMID: 31142822 DOI: 10.1038/s41579-019-0201-x] [Citation(s) in RCA: 236] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The defining feature of the Gram-negative cell envelope is the presence of two cellular membranes, with the specialized glycolipid lipopolysaccharide (LPS) exclusively found on the surface of the outer membrane. The surface layer of LPS contributes to the stringent permeability properties of the outer membrane, which is particularly resistant to permeation of many toxic compounds, including antibiotics. As a common surface antigen, LPS is recognized by host immune cells, which mount defences to clear pathogenic bacteria. To alter properties of the outer membrane or evade the host immune response, Gram-negative bacteria chemically modify LPS in a wide variety of ways. Here, we review key features and physiological consequences of LPS biogenesis and modifications.
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Affiliation(s)
- Brent W Simpson
- Department of Infectious Diseases, University of Georgia, Athens, GA, USA
| | - M Stephen Trent
- Department of Infectious Diseases, University of Georgia, Athens, GA, USA. .,Center for Vaccines and Immunology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA. .,Department of Microbiology, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, USA.
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2
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Molecular mechanisms of polymyxin resistance and detection of mcr genes. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2018; 163:28-38. [PMID: 30439931 DOI: 10.5507/bp.2018.070] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 10/26/2018] [Indexed: 12/12/2022] Open
Abstract
Antibiotic resistance is an ever-increasing global problem. Major commercial antibiotics often fail to fight common bacteria, and some pathogens have become multi-resistant. Polymyxins are potent bactericidal antibiotics against gram-negative bacteria. Known resistance to polymyxin includes intrinsic, mutational and adaptive mechanisms, with the recently described horizontally acquired resistance mechanisms. In this review, we present several strategies for bacteria to develop enhanced resistance to polymyxins, focusing on changes in the outer membrane, efflux and other resistance determinants. Better understanding of the genes involved in polymyxin resistance may pave the way for the development of new and effective antimicrobial agents. We also report novel in silico tested primers for PCR assay that may be able distinguish colistin-resistant isolates carrying the plasmid-encoded mcr genes and will assist in combating the spread of colistin resistance in bacteria.
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Homologous Recombination in Core Genomes Facilitates Marine Bacterial Adaptation. Appl Environ Microbiol 2018; 84:AEM.02545-17. [PMID: 29572211 DOI: 10.1128/aem.02545-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/20/2018] [Indexed: 01/01/2023] Open
Abstract
Acquisition of ecologically relevant genes is common among ocean bacteria, but whether it has a major impact on genome evolution in marine environments remains unknown. Here, we analyzed the core genomes of 16 phylogenetically diverse and ecologically relevant bacterioplankton lineages, each consisting of up to five genomes varying at the strain level. Statistical approaches identified from each lineage up to ∼50 loci showing anomalously high divergence at synonymous sites, which is best explained by recombination with distantly related organisms. The enriched gene categories in these outlier loci match well with the characteristics previously identified as the key phenotypes of these lineages. Examples are antibiotic synthesis and detoxification in Phaeobacter inhibens, exopolysaccharide production in Alteromonas macleodii, hydrocarbon degradation in Marinobacter hydrocarbonoclasticus, and cold adaptation in Pseudoalteromonas haloplanktis Intriguingly, the outlier loci feature polysaccharide catabolism in Cellulophaga baltica but not in Cellulophaga lytica, consistent with their primary habitat preferences in macroalgae and beach sands, respectively. Likewise, analysis of Prochlorococcus showed that photosynthesis-related genes listed in the outlier loci are found only in the high-light-adapted ecotype and not in the low-light adapted ecotype. These observations strongly suggest that recombination with distant relatives is a key mechanism driving the ecological diversification among marine bacterial lineages.IMPORTANCE Acquisition of new metabolic genes has been known as an important mechanism driving bacterial evolution and adaptation in the ocean, but acquisition of novel alleles of existing genes and its potential ecological role have not been examined. Guided by population genetic theories, our genomic analysis showed that divergent allele acquisition is prevalent in phylogenetically diverse marine bacterial lineages and that the affected loci often encode metabolic functions that underlie the known ecological roles of the lineages under study.
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Chen G, Xu Y, Jing J, Mackie B, Zheng X, Zhang X, Wang J, Li X. The anti-sepsis activity of the components of Huanglian Jiedu Decoction with high lipid A-binding affinity. Int Immunopharmacol 2017; 46:87-96. [PMID: 28278436 DOI: 10.1016/j.intimp.2017.02.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/09/2017] [Accepted: 02/27/2017] [Indexed: 12/11/2022]
Abstract
Huanglian Jiedu Decoction (HJD), one of the classic recipes for relieving toxicity and fever, is a common method for treating sepsis in China. However, the effective components of HJD have not yet been identified. This experiment was carried out to elucidate the effective components of HJD against sepsis. Thus, seven fractions from HJD were tested using a biosensor to test their affinity for lipid A. The components obtained that had high lipid A-binding fractions were further separated, and their affinities to lipid A were assessed with the aid of a biosensor. The levels of LPS in the blood were measured, and pathology experiments were conducted. The LPS levels and mRNA expression analysis of TNF-α and IL-6 of the cell supernatant and animal tissue were evaluated to investigate the molecular mechanisms. Palmatine showed the highest affinity to lipid A and was evaluated by in vitro and in vivo experiments. The results of the in vitro and in vivo experiments indicated that the levels of LPS, TNF-α and IL-6 of the palmatine group were significantly lower than those of the sepsis model group (p<0.01). The group treated with palmatine showed strong neutralizing LPS activity in vivo. The palmatine group exhibited stronger protective activity on vital organs compared to the LPS-induced animal model. This verifies that HJD is a viable treatment option for sepsis given that there are multiple components in HJD that neutralize LPS, decrease the release of IL-6 and TNF-α induced by LPS, and protect vital organs.
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Affiliation(s)
- Guirong Chen
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
| | - Yubin Xu
- Key Laboratory of Biological Invasions and Global Changes, College of Biological Science and Technology, Shenyang Agricultural University, Shenyang 110161, China.
| | - Jing Jing
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
| | - Brianna Mackie
- Department of Medicinal Chemistry, Virginia Commonwealth University, 23219, USA
| | - Xinchuan Zheng
- Medical Research Center, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Xu Zhang
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
| | - Jing Wang
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
| | - Xuetao Li
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
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Gaona-López C, Julián-Sánchez A, Riveros-Rosas H. Diversity and Evolutionary Analysis of Iron-Containing (Type-III) Alcohol Dehydrogenases in Eukaryotes. PLoS One 2016; 11:e0166851. [PMID: 27893862 PMCID: PMC5125639 DOI: 10.1371/journal.pone.0166851] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/05/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Alcohol dehydrogenase (ADH) activity is widely distributed in the three domains of life. Currently, there are three non-homologous NAD(P)+-dependent ADH families reported: Type I ADH comprises Zn-dependent ADHs; type II ADH comprises short-chain ADHs described first in Drosophila; and, type III ADH comprises iron-containing ADHs (FeADHs). These three families arose independently throughout evolution and possess different structures and mechanisms of reaction. While types I and II ADHs have been extensively studied, analyses about the evolution and diversity of (type III) FeADHs have not been published yet. Therefore in this work, a phylogenetic analysis of FeADHs was performed to get insights into the evolution of this protein family, as well as explore the diversity of FeADHs in eukaryotes. PRINCIPAL FINDINGS Results showed that FeADHs from eukaryotes are distributed in thirteen protein subfamilies, eight of them possessing protein sequences distributed in the three domains of life. Interestingly, none of these protein subfamilies possess protein sequences found simultaneously in animals, plants and fungi. Many FeADHs are activated by or contain Fe2+, but many others bind to a variety of metals, or even lack of metal cofactor. Animal FeADHs are found in just one protein subfamily, the hydroxyacid-oxoacid transhydrogenase (HOT) subfamily, which includes protein sequences widely distributed in fungi, but not in plants), and in several taxa from lower eukaryotes, bacteria and archaea. Fungi FeADHs are found mainly in two subfamilies: HOT and maleylacetate reductase (MAR), but some can be found also in other three different protein subfamilies. Plant FeADHs are found only in chlorophyta but not in higher plants, and are distributed in three different protein subfamilies. CONCLUSIONS/SIGNIFICANCE FeADHs are a diverse and ancient protein family that shares a common 3D scaffold with a patchy distribution in eukaryotes. The majority of sequenced FeADHs from eukaryotes are distributed in just two subfamilies, HOT and MAR (found mainly in animals and fungi). These two subfamilies comprise almost 85% of all sequenced FeADHs in eukaryotes.
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Affiliation(s)
- Carlos Gaona-López
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM). Cd. Universitaria, Ciudad de México, México
| | - Adriana Julián-Sánchez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM). Cd. Universitaria, Ciudad de México, México
| | - Héctor Riveros-Rosas
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM). Cd. Universitaria, Ciudad de México, México
- * E-mail:
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Zachman-Brockmeyer TR, Thoden JB, Holden HM. Structures of KdnB and KdnA from Shewanella oneidensis: Key Enzymes in the Formation of 8-Amino-3,8-Dideoxy-d-Manno-Octulosonic Acid. Biochemistry 2016; 55:4485-94. [PMID: 27275764 DOI: 10.1021/acs.biochem.6b00439] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
8-Amino-3,8-dideoxy-d-manno-octulosonic acid (Kdo8N) is a unique amino sugar that has thus far only been observed on the lipopolysaccharides of marine bacteria belonging to the genus Shewanella. Although its biological function is still unclear, it is thought that the sugar is important for the integrity of the bacterial cell outer membrane. A three-gene cluster required for the biosynthesis of Kdo8N was first identified in Shewanella oneidensis. Here we describe the three-dimensional structures of two of the enzymes required for Kdo8N biosynthesis in S. oneidensis, namely, KdnB and KdnA. The structure of KdnB was solved to 1.85-Å resolution, and its overall three-dimensional architecture places it into the Group III alcohol dehydrogenase superfamily. A previous study suggested that KdnB did not require NAD(P) for activity. Strikingly, although the protein was crystallized in the absence of any cofactors, the electron density map clearly revealed the presence of a tightly bound NAD(H). In addition, a bound metal was observed, which was shown via X-ray fluorescence to be a zinc ion. Unlike other members of the Group III alcohol dehydrogenases, the dinucleotide cofactor in KdnB is tightly bound and cannot be removed without leading to protein precipitation. With respect to KdnA, it is a pyridoxal 5'-phosphate or (PLP)-dependent aminotransferase. For this analysis, the structure of KdnA, trapped in the presence of the external aldimine with PLP and glutamate, was determined to 2.15-Å resolution. The model of KdnA represents the first structure of a sugar aminotransferase that functions on an 8-oxo sugar. Taken together the results reported herein provide new molecular insight into the biosynthesis of Kdo8N.
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Affiliation(s)
| | - James B Thoden
- Department of Biochemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
| | - Hazel M Holden
- Department of Biochemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
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Chen GR, Zhang G, Li MY, Jing J, Wang J, Zhang X, Mackie B, Dou DQ. The effective components of Huanglian Jiedu Decoction against sepsis evaluated by a lipid A-based affinity biosensor. JOURNAL OF ETHNOPHARMACOLOGY 2016; 186:369-376. [PMID: 27045865 DOI: 10.1016/j.jep.2016.03.064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 03/22/2016] [Accepted: 03/30/2016] [Indexed: 06/05/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Huanglian Jiedu Decoction (HJD), the classical recipe for relieving fever and toxicity, has been used for treating sepsis in China for sixteen years. However, the effective components of HJD have not been elucidated until now. Therefore, there is a need to elucidate the effective components of HJD against sepsis on animal models induced by endotoxin (LPS). The affinity force of the effective components of HJD with lipid A was evaluated by a biosensor. MATERIALS AND METHODS Lipid A is regarded as the bioactive center of LPS and is always used as a drug target. In order to obtain the effective components of HJD against sepsis, seven fractions from HJD were tested by a biosensor method for assessing the affinity for lipid A. After further separation, the components were isolated from high lipid A-binding fractions and their affinities to lipid A were assessed with the aid of a biosensor. Their activities were then assayed by an in vivo experiment administered through a tail vein injection. The levels of LPS, TNF-α, and IL-6 from the blood were found and pathology experiments were performed. RESULTS Three out of the seven fractions exhibited high lipid A-binding affinities. Berberine, baicalin and geniposide were obtained from the three high lipid A-binding fractions. The animal experiments indicated that the levels of LPS, TNF-α and IL-6 in the medicated treatment groups were much lower than that of the model group ((**)P<0.01). The medicated treatment groups exhibited stronger protective activities on varying organs in the animal model. CONCLUSIONS Berberine, baicalin and geniposide could neutralize LPS by binding with lipid A and then reduce the release of IL-6 and TNF-α induced by LPS. Furthermore, berberine, baicalin and geniposide exhibited protective activities on varying organs compared to the animal model established by the LPS-induced. These results validate that the components from HJD neutralized LPS and then depressed the release of IL-6 and TNF-α induced by LPS. This gives further evidence that HJD would be a suitable treatment for sepsis and protecting vital organs.
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Affiliation(s)
- Gui-Rong Chen
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China.
| | - Gang Zhang
- Department of Medicinal Chemistry, Virginia Commonwealth University, 23219, USA
| | - Ming-Yu Li
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
| | - Jing Jing
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
| | - Jing Wang
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
| | - Xu Zhang
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
| | - Brianna Mackie
- Department of Medicinal Chemistry, Virginia Commonwealth University, 23219, USA
| | - De-Qiang Dou
- College of Pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life One Road, DD port, Dalian 116600, China
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Telke AA, Rolain JM. Functional genomics to discover antibiotic resistance genes: The paradigm of resistance to colistin mediated by ethanolamine phosphotransferase in Shewanella algae MARS 14. Int J Antimicrob Agents 2015; 46:648-52. [PMID: 26498987 DOI: 10.1016/j.ijantimicag.2015.09.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 09/01/2015] [Accepted: 09/03/2015] [Indexed: 02/06/2023]
Abstract
Shewanella algae MARS 14 is a colistin-resistant clinical isolate retrieved from bronchoalveolar lavage of a hospitalised patient. A functional genomics strategy was employed to discover the molecular support for colistin resistance in S. algae MARS 14. A pZE21 MCS-1 plasmid-based genomic expression library was constructed in Escherichia coli TOP10. The estimated library size was 1.30×10(8) bp. Functional screening of colistin-resistant clones was carried out on Luria-Bertani agar containing 8 mg/L colistin. Five colistin-resistant clones were obtained after complete screening of the genomic expression library. Analysis of DNA sequencing results found a unique gene in all selected clones. Amino acid sequence analysis of this unique gene using the Integrated Microbial Genomes (IMG) and KEGG databases revealed that this gene encodes ethanolamine phosphotransferase (EptA, or so-called PmrC). Reverse transcription PCR analysis indicated that resistance to colistin in S. algae MARS 14 was associated with overexpression of EptA (27-fold increase), which plays a crucial role in the arrangement of outer membrane lipopolysaccharide.
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Affiliation(s)
- Amar A Telke
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France
| | - Jean-Marc Rolain
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France.
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Jacobson KH, Gunsolus IL, Kuech TR, Troiano JM, Melby ES, Lohse SE, Hu D, Chrisler WB, Murphy CJ, Orr G, Geiger FM, Haynes CL, Pedersen JA. Lipopolysaccharide Density and Structure Govern the Extent and Distance of Nanoparticle Interaction with Actual and Model Bacterial Outer Membranes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:10642-10650. [PMID: 26207769 PMCID: PMC4643684 DOI: 10.1021/acs.est.5b01841] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Design of nanomedicines and nanoparticle-based antimicrobial and antifouling formulations and assessment of the potential implications of nanoparticle release into the environment requires understanding nanoparticle interaction with bacterial surfaces. Here we demonstrate the electrostatically driven association of functionalized nanoparticles with lipopolysaccharides of Gram-negative bacterial outer membranes and find that lipopolysaccharide structure influences the extent and location of binding relative to the outer leaflet-solution interface. By manipulating the lipopolysaccharide content in Shewanella oneidensis outer membranes, we observed the electrostatically driven interaction of cationic gold nanoparticles with the lipopolysaccharide-containing leaflet. We probed this interaction by quartz crystal microbalance with dissipation monitoring (QCM-D) and second harmonic generation (SHG) using solid-supported lipopolysaccharide-containing bilayers. The association of cationic nanoparticles increased with lipopolysaccharide content, while no association of anionic nanoparticles was observed. The harmonic-dependence of QCM-D measurements suggested that a population of the cationic nanoparticles was held at a distance from the outer leaflet-solution interface of bilayers containing smooth lipopolysaccharides (those bearing a long O-polysaccharide). Additionally, smooth lipopolysaccharides held the bulk of the associated cationic particles outside of the interfacial zone probed by SHG. Our results demonstrate that positively charged nanoparticles are more likely to interact with Gram-negative bacteria than are negatively charged particles, and this interaction occurs primarily through lipopolysaccharides.
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Affiliation(s)
- Kurt H. Jacobson
- Department of Civil and Environmental Engineering, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Ian L. Gunsolus
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Thomas R. Kuech
- Environmental Chemistry and Technology Program, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Julianne M. Troiano
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Eric S. Melby
- Environmental Chemistry and Technology Program, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Samuel E. Lohse
- Department of Chemistry, University of Illinois at Urbana–Champaign, Urbana, Illinois 61801, United States
| | - Dehong Hu
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - William B. Chrisler
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Catherine J. Murphy
- Department of Chemistry, University of Illinois at Urbana–Champaign, Urbana, Illinois 61801, United States
| | - Galya Orr
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Franz M. Geiger
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Christy L. Haynes
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Corresponding Authors: Phone: 608-263-4971; . Phone: 612-626-1096,
| | - Joel A. Pedersen
- Department of Civil and Environmental Engineering, University of Wisconsin, Madison, Wisconsin 53706, United States
- Environmental Chemistry and Technology Program, University of Wisconsin, Madison, Wisconsin 53706, United States
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
- Corresponding Authors: Phone: 608-263-4971; . Phone: 612-626-1096,
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Wang X, Quinn PJ, Yan A. Kdo2 -lipid A: structural diversity and impact on immunopharmacology. Biol Rev Camb Philos Soc 2014; 90:408-27. [PMID: 24838025 PMCID: PMC4402001 DOI: 10.1111/brv.12114] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 04/10/2014] [Accepted: 04/17/2014] [Indexed: 12/11/2022]
Abstract
3-deoxy-d-manno-octulosonic acid-lipid A (Kdo2-lipid A) is the essential component of lipopolysaccharide in most Gram-negative bacteria and the minimal structural component to sustain bacterial viability. It serves as the active component of lipopolysaccharide to stimulate potent host immune responses through the complex of Toll-like-receptor 4 (TLR4) and myeloid differentiation protein 2. The entire biosynthetic pathway of Escherichia coli Kdo2-lipid A has been elucidated and the nine enzymes of the pathway are shared by most Gram-negative bacteria, indicating conserved Kdo2-lipid A structure across different species. Yet many bacteria can modify the structure of their Kdo2-lipid A which serves as a strategy to modulate bacterial virulence and adapt to different growth environments as well as to avoid recognition by the mammalian innate immune systems. Key enzymes and receptors involved in Kdo2-lipid A biosynthesis, structural modification and its interaction with the TLR4 pathway represent a clear opportunity for immunopharmacological exploitation. These include the development of novel antibiotics targeting key biosynthetic enzymes and utilization of structurally modified Kdo2-lipid A or correspondingly engineered live bacteria as vaccines and adjuvants. Kdo2-lipid A/TLR4 antagonists can also be applied in anti-inflammatory interventions. This review summarizes recent knowledge on both the fundamental processes of Kdo2-lipid A biosynthesis, structural modification and immune stimulation, and applied research on pharmacological exploitations of these processes for therapeutic development.
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Affiliation(s)
- Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, China
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Chu M, Ding R, Chu ZY, Zhang MB, Liu XY, Xie SH, Zhai YJ, Wang YD. Role of berberine in anti-bacterial as a high-affinity LPS antagonist binding to TLR4/MD-2 receptor. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 14:89. [PMID: 24602493 PMCID: PMC3946165 DOI: 10.1186/1472-6882-14-89] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 02/18/2014] [Indexed: 12/14/2022]
Abstract
BACKGROUND Berberine is an isoquinoline alkaloid mainly extracted from Rhizoma Coptidis and has been shown to possess a potent inhibitory activity against bacterial. However, the role of berberine in anti-bacterial action has not been extensively studied. METHODS The animal model was established to investigate the effects of berberine on bacterial and LPS infection. Docking analysis, Molecular dynamics simulations and Real-time RT-PCR analysis was adopted to investigate the molecular mechanism. RESULTS Treatment with 40 mg/kg berberine significantly increased the survival rate of mice challenged with Salmonella typhimurium (LT2), but berberine show no effects in bacteriostasis. Further study indicated that treatment with 0.20 g/kg berberine markedly increased the survival rate of mice challenged with 2 EU/ml bacterial endotoxin (LPS) and postpone the death time of the dead mice. Moreover, pretreatment with 0.05 g/kg berberine significantly lower the increasing temperature of rabbits challenged with LPS. The studies of molecular mechanism demonstrated that Berberine was able to bind to the TLR4/MD-2 receptor, and presented higher affinity in comparison with LPS. Furthermore, berberine could significantly suppressed the increasing expression of NF-κB, IL-6, TNFα, and IFNβ in the RAW264.7 challenged with LPS. CONCLUSION Berberine can act as a LPS antagonist and block the LPS/TLR4 signaling from the sourse, resulting in the anti-bacterial action.
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Abstract
Lipopolysaccharide molecules represent a unique family of glycolipids based on a highly conserved lipid moiety known as lipid A. These molecules are produced by most gram-negative bacteria, in which they play important roles in the integrity of the outer-membrane permeability barrier and participate extensively in host-pathogen interplay. Few bacteria contain lipopolysaccharide molecules composed only of lipid A. In most forms, lipid A is glycosylated by addition of the core oligosaccharide that, in some bacteria, provides an attachment site for a long-chain O-antigenic polysaccharide. The complexity of lipopolysaccharide structures is reflected in the processes used for their biosynthesis and export. Rapid growth and cell division depend on the bacterial cell's capacity to synthesize and export lipopolysaccharide efficiently and in large amounts. We review recent advances in those processes, emphasizing the reactions that are essential for viability.
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Affiliation(s)
- Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada;
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13
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Lodowska J, Wolny D, Węglarz L. The sugar 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) as a characteristic component of bacterial endotoxin — a review of its biosynthesis, function, and placement in the lipopolysaccharide core. Can J Microbiol 2013; 59:645-55. [DOI: 10.1139/cjm-2013-0490] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The sugar 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) is a characteristic component of bacterial lipopolysaccharide (LPS, endotoxin). It connects the carbohydrate part of LPS with C6 of glucosamine or 2,3-diaminoglucose of lipid A by acid-labile α-ketosidic linkage. The number of Kdo units present in LPS, the way they are connected, and the occurrence of other substituents (P, PEtn, PPEtn, Gal, or β-l-Ara4N) account for structural diversity of the inner core region of endotoxin. In a majority of cases, Kdo is crucial to the viability and growth of bacterial cells. In this paper, the biosynthesis of Kdo and the mechanism of its incorporation into the LPS structure, as well as the location of this unique component in the endotoxin core structures, have been described.
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Affiliation(s)
- Jolanta Lodowska
- Department of Biochemistry, Faculty of Pharmacy, Medical University of Silesia, Narcyzow 1 Street, 41-200 Sosnowiec, Poland
| | - Daniel Wolny
- Department of Biopharmacy, Faculty of Pharmacy, Medical University of Silesia, Narcyzow 1 St., 41-200 Sosnowiec, Poland
| | - Ludmiła Węglarz
- Department of Biochemistry, Faculty of Pharmacy, Medical University of Silesia, Narcyzow 1 Street, 41-200 Sosnowiec, Poland
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