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Lipopolysaccharides 2.0
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Lipopolysaccharides 2.0

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Biology".

Deadline for manuscript submissions: closed (15 January 2024) | Viewed by 6628

Special Issue Editors

Prof. Dr. Satish Raina

E-Mail Website
Guest Editor
Unit of Bacterial Genetics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
Interests: protein folding; heat shock response; peptidyl prolyl cis/trans isomerases; disulfide bond formation; RpoE sigma factor; two-component systems; envelope stress; transcription factors; lipopolysaccharide
Special Issues, Collections and Topics in MDPI journals
Dr. Gracjana Klein

E-Mail Website
Guest Editor
Unit of Bacterial Genetics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
Interests: heat shock proteins; envelope stress response; protein folding catalysts; prolyl isomerase; LPS biosynthesis; LPS assembly; LPS modifications; non-coding regulatory RNAs; proteases; phosphatases; kinases
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The most conserved and defining feature of Gram-negative bacteria is the presence of an asymmetric outer membrane (OM), with phospholipids facing its inner leaflet and lipopolysaccharide (LPS) on the outer surface. LPS constitutes the major component of OM, and is the causative agent of sepsis. LPS is a complex glycolipid comprised of a hydrophobic membrane-anchored lipid A and a core oligosaccharide, which is linked to O-antigen in smooth-type bacteria. The lipid A part constitutes the endotoxin principal and is highly conserved. LPSs are potent activators of the mammalian immune system. LPS composition is  highly heterogenous, and this heterogeneity arises due to the incorporation of non-stoichiometric modifications, alterations in acyl chain length which contribute to antibiotic resistance, and evasion of host immune system. Recent studies have unraveled novel essential components in the regulation of a tight balance between LPS and phospholipid content, and discovery of new information on the LPS transport to the OM. Regulated assembly of LPS, structural diversity, new LPS structures, LPS transport, and recognition of LPS by host immune system will be the focus of this issue. 

Prof. Dr. Satish Raina
Dr. Gracjana Klein
Guest Editors

Manuscript Submission Information

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Keywords

  • lipid A and its biosynthesis
  • assembly and transport of LPS
  • regulation of the LpxC
  • chemical structure
  • regulated LPS modifications
  • LPS and virulence
  • recognition of LPS by immune system
  • antibiotic resistance
  • vaccines
  • envelope stress

Related Special Issue

Published Papers (6 papers)

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Research

25 pages, 4466 KiB  
Article
Diversity, Complexity, and Specificity of Bacterial Lipopolysaccharide (LPS) Structures Impacting Their Detection and Quantification
by Flavien Dardelle, Capucine Phelip, Maryam Darabi, Tatiana Kondakova, Xavier Warnet, Edyta Combret, Eugenie Juranville, Alexey Novikov, Jerome Kerzerho and Martine Caroff
Int. J. Mol. Sci. 2024, 25(7), 3927; https://doi.org/10.3390/ijms25073927 - 31 Mar 2024
Viewed by 736
Abstract
Endotoxins are toxic lipopolysaccharides (LPSs), extending from the outer membrane of Gram-negative bacteria and notorious for their toxicity and deleterious effects. The comparison of different LPSs, isolated from various Gram-negative bacteria, shows a global similar architecture corresponding to a glycolipid lipid A moiety, [...] Read more.
Endotoxins are toxic lipopolysaccharides (LPSs), extending from the outer membrane of Gram-negative bacteria and notorious for their toxicity and deleterious effects. The comparison of different LPSs, isolated from various Gram-negative bacteria, shows a global similar architecture corresponding to a glycolipid lipid A moiety, a core oligosaccharide, and outermost long O-chain polysaccharides with molecular weights from 2 to 20 kDa. LPSs display high diversity and specificity among genera and species, and each bacterium contains a unique set of LPS structures, constituting its protective external barrier. Some LPSs are not toxic due to their particular structures. Different, well-characterized, and highly purified LPSs were used in this work to determine endotoxin detection rules and identify their impact on the host. Endotoxin detection is a major task to ensure the safety of human health, especially in the pharma and food sectors. Here, we describe the impact of different LPS structures obtained under different bacterial growth conditions on selective LPS detection methods such as LAL, HEK-blue TLR-4, LC-MS2, and MALDI-MS. In these various assays, LPSs were shown to respond differently, mainly attributable to their lipid A structures, their fatty acid numbers and chain lengths, the presence of phosphate groups, and their possible substitutions. Full article
(This article belongs to the Special Issue Lipopolysaccharides 2.0)
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17 pages, 3310 KiB  
Article
Structure, Physicochemical Properties and Biological Activity of Lipopolysaccharide from the Rhizospheric Bacterium Ochrobactrum quorumnocens T1Kr02, Containing d-Fucose Residues
by Aleksandra A. Krivoruchko, Evelina L. Zdorovenko, Maria F. Ivanova, Ekaterina E. Kostina, Yulia P. Fedonenko, Alexander S. Shashkov, Andrey S. Dmitrenok, Elizaveta A. Ul’chenko, Oksana V. Tkachenko, Anastasia S. Astankova and Gennady L. Burygin
Int. J. Mol. Sci. 2024, 25(4), 1970; https://doi.org/10.3390/ijms25041970 - 06 Feb 2024
Viewed by 562
Abstract
Lipopolysaccharides (LPSs) are major components of the outer membranes of Gram-negative bacteria. In this work, the structure of the O-polysaccharide of Ochrobactrum quorumnocens T1Kr02 was identified by nuclear magnetic resonance (NMR), and the physical–chemical properties and biological activity of LPS were also investigated. [...] Read more.
Lipopolysaccharides (LPSs) are major components of the outer membranes of Gram-negative bacteria. In this work, the structure of the O-polysaccharide of Ochrobactrum quorumnocens T1Kr02 was identified by nuclear magnetic resonance (NMR), and the physical–chemical properties and biological activity of LPS were also investigated. The NMR analysis showed that the O-polysaccharide has the following structure: →2)-β-d-Fucf-(1→3)-β-d-Fucp-(1→. The structure of the periplasmic glucan coextracted with LPS was established by NMR spectroscopy and chemical methods: →2)-β-d-Glcp-(1→. Non-stoichiometric modifications were identified in both polysaccharides: 50% of d-fucofuranose residues at position 3 were O-acetylated, and 15% of d-Glcp residues at position 6 were linked with succinate. This is the first report of a polysaccharide containing both d-fucopyranose and d-fucofuranose residues. The fatty acid analysis of the LPS showed the prevalence of 3-hydroxytetradecanoic, hexadecenoic, octadecenoic, lactobacillic, and 27-hydroxyoctacosanoic acids. The dynamic light scattering demonstrated that LPS (in an aqueous solution) formed supramolecular particles with a size of 72.2 nm and a zeta-potential of –21.5 mV. The LPS solution (10 mkg/mL) promoted the growth of potato microplants under in vitro conditions. Thus, LPS of O. quorumnocens T1Kr02 can be recommended as a promoter for plants and as a source of biotechnological production of d-fucose. Full article
(This article belongs to the Special Issue Lipopolysaccharides 2.0)
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22 pages, 3480 KiB  
Article
Radiation-Detoxified Form of Endotoxin Effectively Activates Th1 Responses and Attenuates Ragweed-Induced Th2-Type Airway Inflammation in Mice
by Attila Bácsi, Beatrix Ágics, Kitti Pázmándi, Béla Kocsis, Viktor Sándor, Lóránd Bertók, Geza Bruckner and Sándor Sipka
Int. J. Mol. Sci. 2024, 25(3), 1581; https://doi.org/10.3390/ijms25031581 - 27 Jan 2024
Viewed by 656
Abstract
Urbanization with reduced microbial exposure is associated with an increased burden of asthma and atopic symptoms. Conversely, environmental exposure to endotoxins in childhood can protect against the development of allergies. Our study aimed to investigate whether the renaturation of the indoor environment with [...] Read more.
Urbanization with reduced microbial exposure is associated with an increased burden of asthma and atopic symptoms. Conversely, environmental exposure to endotoxins in childhood can protect against the development of allergies. Our study aimed to investigate whether the renaturation of the indoor environment with aerosolized radiation-detoxified lipopolysaccharide (RD-LPS) has a preventative effect against the development of ragweed-induced Th2-type airway inflammation. To explore this, cages of six-week-old BALB/c mice were treated daily with aerosolized native LPS (N-LPS) or RD-LPS. After a 10-week treatment period, mice were sensitized and challenged with ragweed pollen extract, and inflammatory cell infiltration into the airways was observed. As dendritic cells (DCs) play a crucial role in the polarization of T-cell responses, in our in vitro experiments, the effects of N-LPS and RD-LPS were compared on human monocyte-derived DCs (moDCs). Mice in RD-LPS-rich milieu developed significantly less allergic airway inflammation than mice in N-LPS-rich or common environments. The results of our in vitro experiments demonstrate that RD-LPS-exposed moDCs have a higher Th1-polarizing capacity than moDCs exposed to N-LPS. Consequently, we suppose that the aerosolized, non-toxic RD-LPS applied in early life for the renaturation of urban indoors may be suitable for the prevention of Th2-mediated allergies in childhood. Full article
(This article belongs to the Special Issue Lipopolysaccharides 2.0)
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24 pages, 3394 KiB  
Article
Biosynthesis of the Inner Core of Bordetella pertussis Lipopolysaccharides: Effect of Mutations on LPS Structure, Cell Division, and Toll-like Receptor 4 Activation
by Jesús Pérez-Ortega, Ria van Boxtel, Michel Plisnier, Dominique Ingels, Nathalie Devos, Steven Sijmons and Jan Tommassen
Int. J. Mol. Sci. 2023, 24(24), 17313; https://doi.org/10.3390/ijms242417313 - 09 Dec 2023
Viewed by 1834
Abstract
Previously developed whole-cell vaccines against Bordetella pertussis, the causative agent of whooping cough, appeared to be too reactogenic due to their endotoxin content. Reduction in endotoxicity can generally be achieved through structural modifications in the lipid A moiety of lipopolysaccharides (LPS). In [...] Read more.
Previously developed whole-cell vaccines against Bordetella pertussis, the causative agent of whooping cough, appeared to be too reactogenic due to their endotoxin content. Reduction in endotoxicity can generally be achieved through structural modifications in the lipid A moiety of lipopolysaccharides (LPS). In this study, we found that dephosphorylation of lipid A in B. pertussis through the heterologous production of the phosphatase LpxE from Francisella novicida did, unexpectedly, not affect Toll-like receptor 4 (TLR4)-stimulating activity. We then focused on the inner core of LPS, whose synthesis has so far not been studied in B. pertussis. The kdtA and kdkA genes, responsible for the incorporation of a single 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) residue in the inner core and its phosphorylation, respectively, appeared to be essential. However, the Kdo-bound phosphate could be replaced by a second Kdo after the heterologous production of Escherichia coli kdtA. This structural change in the inner core affected outer-core and lipid A structures and also bacterial physiology, as reflected in cell filamentation and a switch in virulence phase. Furthermore, the eptB gene responsible for the non-stoichiometric substitution of Kdo-bound phosphate with phosphoethanolamine was identified and inactivated. Interestingly, the constructed inner-core modifications affected TLR4-stimulating activity. Whereas endotoxicity studies generally focus on the lipid A moiety, our data demonstrate that structural changes in the inner core can also affect TLR4-stimulating activity. Full article
(This article belongs to the Special Issue Lipopolysaccharides 2.0)
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28 pages, 5465 KiB  
Article
Suppressors of lapC Mutation Identify New Regulators of LpxC, Which Mediates the First Committed Step in Lipopolysaccharide Biosynthesis
by Akshay Maniyeri, Alicja Wieczorek, Aravind Ayyolath, Weronika Sugalska, Gracjana Klein and Satish Raina
Int. J. Mol. Sci. 2023, 24(20), 15174; https://doi.org/10.3390/ijms242015174 - 14 Oct 2023
Viewed by 1127
Abstract
Gram-negative bacteria, such as Escherichia coli, are characterized by an asymmetric outer membrane (OM) with lipopolysaccharide (LPS) located in the outer leaflet and phospholipids facing the inner leaflet. E. coli recruits LPS assembly proteins LapB, LapC and LapD in concert with [...] Read more.
Gram-negative bacteria, such as Escherichia coli, are characterized by an asymmetric outer membrane (OM) with lipopolysaccharide (LPS) located in the outer leaflet and phospholipids facing the inner leaflet. E. coli recruits LPS assembly proteins LapB, LapC and LapD in concert with FtsH protease to ensure a balanced biosynthesis of LPS and phospholipids. We recently reported that bacteria either lacking the periplasmic domain of the essential LapC protein (lapC190) or in the absence of LapD exhibit an elevated degradation of LpxC, which catalyzes the first committed step in LPS biosynthesis. To further understand the functions of LapC and LapD in regulating LPS biosynthesis, we show that the overproduction of the intact LapD suppresses the temperature sensitivity (Ts) of lapC190, but not when either its N-terminal transmembrane anchor or specific conserved amino acids in the C-terminal domain are mutated. Moreover, overexpression of srrA, marA, yceJ and yfgM genes can rescue the Ts phenotype of lapC190 bacteria by restoring LpxC amounts. We further show that MarA-mediated suppression requires the expression of mla genes, whose products participate in the maintenance of OM asymmetry, and the SrrA-mediated suppression requires the presence of cardiolipin synthase A. Full article
(This article belongs to the Special Issue Lipopolysaccharides 2.0)
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15 pages, 3950 KiB  
Article
How Alligator Immune Peptides Kill Gram-Negative Bacteria: A Lipid-Scrambling, Squeezing, and Extracting Mechanism Revealed by Theoretical Simulations
by Xiangyuan Li, Lei Fu, Shan Zhang, Yipeng Wang and Lianghui Gao
Int. J. Mol. Sci. 2023, 24(13), 10962; https://doi.org/10.3390/ijms241310962 - 30 Jun 2023
Viewed by 992
Abstract
Alligator sinensis cathelicidins (As-CATHs) are antimicrobial peptides extracted from alligators that enable alligators to cope with diseases caused by bacterial infections. This study assessed the damaging effects of sequence-truncated and residue-substituted variants of As-CATH4, AS4-1, AS4-5, and AS4-9 (with decreasing charges but increasing [...] Read more.
Alligator sinensis cathelicidins (As-CATHs) are antimicrobial peptides extracted from alligators that enable alligators to cope with diseases caused by bacterial infections. This study assessed the damaging effects of sequence-truncated and residue-substituted variants of As-CATH4, AS4-1, AS4-5, and AS4-9 (with decreasing charges but increasing hydrophobicity) on the membranes of Gram-negative bacteria at the molecular level by using coarse-grained molecular dynamics simulations. The simulations predicted that all the variants disrupt the structures of the inner membrane of Gram-negative bacteria, with AS4-9 having the highest antibacterial activity that is able to squeeze the membrane and extract lipids from the membrane. However, none of them can disrupt the structure of asymmetric outer membrane of Gram-negative bacteria, which is composed of lipopolysaccharides in the outer leaflet and phospholipids in the inner leaflet. Nonetheless, the adsorption of AS4-9 induces lipid scrambling in the membrane by lowering the free energy of a phospholipid flipping from the inner leaflet up to the outer leaflet. Upon binding onto the lipid-scrambled outer membrane, AS4-9s are predicted to squeeze and extract phospholipids from the membrane, AS4-5s have a weak pull-out effect, and AS4-1s mainly stay free in water without any lipid-extracting function. These findings provide inspiration for the development of potent therapeutic agents targeting bacteria. Full article
(This article belongs to the Special Issue Lipopolysaccharides 2.0)
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