Structural analysis of lipopolysaccharides from Gram-negative bacteria

Kabanov, D. S.; Прохоренко, И. Р.

doi:10.1134/s0006297910040012

Cited by 62 publications

(50 citation statements)

References 194 publications

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“…Moreover, the inherent chemical heterogeneity of a particular LPS, derived from the interconnection of its three very different regions, makes it challenging to isolate and characterize (33,38,39). Beyond this, structural variations can also occur within the LPS of the same organism (39).…”

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confidence: 99%

“…There is extensive component variety within this general LPS structural organization, with each organism displaying specific modifications (24,28,30,31,33,(36)(37)(38). Moreover, the inherent chemical heterogeneity of a particular LPS, derived from the interconnection of its three very different regions, makes it challenging to isolate and characterize (33,38,39).…”

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confidence: 99%

“…The general architecture of LPS includes three distinct regions: lipid A, core oligosaccharides, and O antigen (28,(30)(31)(32). Lipid A is a unique carbohydrate-lipid, typically a (␤-1,6)-D-glucosamine (GlcN) disaccharide linked to a varied number of fatty acids (FAs) and hydroxy-FAs (HOFAs) (30,33,34), and it is anchored by its lipophilic domain in the OM lipid bilayer (27). A second LPS region, the core oligosaccharide, typically holds the characteristic component 2-keto 3-deoxy-D-manno-octulosonate (Kdo) or, less typically, D-glycero-D-talo-2-octulopyranosonic acid (Ko) (30,35).…”

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confidence: 99%

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Global and Targeted Lipid Analysis of Gemmata obscuriglobus Reveals the Presence of Lipopolysaccharide, a Signature of the Classical Gram-Negative Outer Membrane

et al. 2016

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Planctomycete bacteria possess many unusual cellular properties, contributing to a cell plan long considered to be unique among the bacteria. However, data from recent studies are more consistent with a modified Gram-negative cell plan. A key feature of the Gram-negative plan is the presence of an outer membrane (OM), for which lipopolysaccharide (LPS) is a signature molecule. Despite genomic evidence for an OM in planctomycetes, no biochemical verification has been reported. We attempted to detect and characterize LPS in the planctomycete Gemmata obscuriglobus. We obtained direct evidence for LPS and lipid A using electrophoresis and differential staining. Gas chromatography-mass spectrometry (GC-MS) compositional analysis of LPS extracts identified eight different 3-hydroxy fatty acids (3-HOFAs), 2-keto 3-deoxy-D-manno-octulosonic acid (Kdo), glucosamine, and hexose and heptose sugars, a chemical profile unique to Gram-negative LPS. Combined with molecular/structural information collected from matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS analysis of putative intact lipid A, these data led us to propose a heterogeneous hexa-acylated lipid A structure (multiple-lipid A species). We also confirmed previous reports of G. obscuriglobus whole-cell fatty acid (FA) and sterol compositions and detected a novel polyunsaturated FA (PUFA). Our confirmation of LPS, and by implication an OM, in G. obscuriglobus raises the possibility that other planctomycetes possess an OM. The pursuit of this question, together with studies of the structural connections between planctomycete LPS and peptidoglycans, will shed more light on what appears to be a planctomycete variation on the Gram-negative cell plan. IMPORTANCEBacterial species are classified as Gram positive or negative based on their cell envelope structure. For 25 years, the envelope of planctomycete bacteria has been considered a unique exception, as it lacks peptidoglycan and an outer membrane (OM). However, the very recent detection of peptidoglycan in planctomycete species has provided evidence for a more conventional cell wall and raised questions about other elements of the cell envelope. Here, we report direct evidence of lipopolysaccharide in the planctomycete G. obscuriglobus, suggesting the presence of an OM and supporting the proposal that the planctomycete cell envelope is an extension of the canonical Gram-negative plan. This interpretation features a convoluted cytoplasmic membrane and expanded periplasmic space, the functions of which provide an intriguing avenue for future investigation.T he planctomycete bacterium Gemmata obscuriglobus (1) is of considerable interest to the fields of cell and evolutionary biology due to its uncommon cellular features and evolutionary placement within the Bacteria (2-5). G. obscuriglobus possesses an extensive endomembrane system (6) with superficial eukaryotelike properties, including the presence of membrane coat-like (MC-like) proteins (7), large quantities of sterols (8, 9), a propos...

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Global and Targeted Lipid Analysis of Gemmata obscuriglobus Reveals the Presence of Lipopolysaccharide, a Signature of the Classical Gram-Negative Outer Membrane

et al. 2016

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“…5), implying that the ability of B. pseudomallei to regulate these two negative regulators for the evasion of macrophage killing may be at least dependent on the atypical nature of its LPS. It should be noted that typical and atypical types of LPS share a general structure of LPS; however, the atypical LPS differs from the typical type by bearing the substituents in the phosphate group and the variable and long fatty-acid chain in lipid A (47). Due to such features, it has been previously demonstrated that the atypical LPS is recognized and responded to by the TLRs in a manner different from that seen with the typical LPS (46).…”

Section: Discussionmentioning

confidence: 95%

Sterile-α- and Armadillo Motif-Containing Protein Inhibits the TRIF-Dependent Downregulation of Signal Regulatory Protein α To Interfere with Intracellular Bacterial Elimination in Burkholderia pseudomallei-Infected Mouse Macrophages

Baral

Utaisincharoen

2013

Infect Immun

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Burkholderia pseudomallei, the causative agent of melioidosis, evades macrophage killing by suppressing the TRIF-dependent pathway, leading to inhibition of inducible nitric oxide synthase (iNOS) expression. We previously demonstrated that virulent wild-type B. pseudomallei inhibits the TRIF-dependent pathway by upregulating sterile-␣-and armadillo motif-containing protein (SARM) and by inhibiting downregulation of signal regulatory protein ␣ (SIRP␣); both molecules are negative regulators of Toll-like receptor signaling. In contrast, the less virulent lipopolysaccharide (LPS) mutant of B. pseudomallei is unable to exhibit these features and is susceptible to macrophage killing. However, the functional relationship of these two negative regulators in the evasion of macrophage defense has not been elucidated. We demonstrated here that SIRP␣ downregulation was observed after inhibition of SARM expression by small interfering RNA in wild-type-infected macrophages, indicating that SIRP␣ downregulation is regulated by SARM. Furthermore, this downregulation requires activation of the TRIF signaling pathway, as we observed abrogation of SIRP␣ downregulation as well as restricted bacterial growth in LPS mutant-infected TRIF-depleted macrophages. Although inhibition of SARM expression is correlated to SIRP␣ downregulation and iNOS upregulation in gamma interferon-activated wild-type-infected macrophages, these phenomena appear to bypass the TRIF-dependent pathway. Similar to live bacteria, the wild-type LPS is able to upregulate SARM and to prevent SIRP␣ downregulation, implying that the LPS of B. pseudomallei may play a crucial role in regulating the expression of these two negative regulators. Altogether, our findings show a previously unrecognized role of B. pseudomallei-induced SARM in inhibiting SIRP␣ downregulation-mediated iNOS upregulation, facilitating the ability of the bacterium to multiply in macrophages.

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“…Temperature-dependent inactivation of fabG in E. coli has been shown to suppress synthesis of fatty acids longer than four carbons (72). The length of fatty acid carbon chains is extremely important for the LPS structure; the lipid A molecule is composed of fatty acids longer than 10 carbons in the majority of Gram-negative bacteria (75). Therefore, the relatively minor phenotype change observed in the LEPBIa0050 mutant (no increased SDS and NaCl sensitivity) suggests that its function as fatty acid elongation initiator is supplemented from one of its paralogues.…”

Section: Discussionmentioning

confidence: 99%

Screening of a Leptospira biflexa Mutant Library To Identify Genes Involved in Ethidium Bromide Tolerance

Pětrošová

Picardeau

2014

Appl Environ Microbiol

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bLeptospira spp. are spirochete bacteria comprising both pathogenic and free-living species. The saprophyte L. biflexa is a model bacterium for studying leptospiral biology due to relative ease of culturing and genetic manipulation. In this study, we constructed a library of 4,996 random transposon mutants in L. biflexa. We screened the library for increased susceptibility to the DNA intercalating agent, ethidium bromide (EtBr), in order to identify genetic determinants that reduce L. biflexa susceptibility to antimicrobial agents. By phenotypic screening, using subinhibitory EtBr concentrations, we identified 29 genes that, when disrupted via transposon insertion, led to increased sensitivity of the bacteria to EtBr. At the functional level, these genes could be categorized by function as follows: regulation and signaling (n ‫؍‬ 11), transport (n ‫؍‬ 6), membrane structure (n ‫؍‬ 5), stress response (n ‫؍‬ 2), DNA damage repair (n ‫؍‬ 1), and other processes (n ‫؍‬ 3), while 1 gene had no predicted function. Genes involved in transport (including efflux pumps) and regulation (two-component systems, anti-sigma factor antagonists, etc.) were overrepresented, demonstrating that these genes are major contributors to EtBr tolerance. This finding suggests that transport genes which would prevent EtBr to enter the cell cytoplasm are critical for EtBr resistance. We identified genes required for the growth of L. biflexa in the presence of sublethal EtBr concentration and characterized their potential as antibiotic resistance determinants. This study will help to delineate mechanisms of adaptation to toxic compounds, as well as potential mechanisms of antibiotic resistance development in pathogenic L. interrogans.

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Structural analysis of lipopolysaccharides from Gram-negative bacteria

Cited by 62 publications

References 194 publications

Global and Targeted Lipid Analysis of Gemmata obscuriglobus Reveals the Presence of Lipopolysaccharide, a Signature of the Classical Gram-Negative Outer Membrane

Global and Targeted Lipid Analysis of Gemmata obscuriglobus Reveals the Presence of Lipopolysaccharide, a Signature of the Classical Gram-Negative Outer Membrane

Sterile-α- and Armadillo Motif-Containing Protein Inhibits the TRIF-Dependent Downregulation of Signal Regulatory Protein α To Interfere with Intracellular Bacterial Elimination in Burkholderia pseudomallei-Infected Mouse Macrophages

Screening of a Leptospira biflexa Mutant Library To Identify Genes Involved in Ethidium Bromide Tolerance

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