Bacteroides thetaiotaomicron rough-type lipopolysaccharide: The chemical structure and the immunological activity

Pither, Molly Dorothy; Illiano, Anna; Pagliuca, Chiara; Jacobson, Amy N.; Mantova, Giuseppe; Stornaiuolo, Alessia; Colicchio, Roberta; Vitiello, Mariateresa; Pinto, Gabriella; Silipo, Alba; Fischbach, Michael; Salvatore, Paola; Amoresano, Angela; Molinaro, Antonio; Lorenzo, Flaviana Di

doi:10.1016/j.carbpol.2022.120040

Cited by 19 publications

(13 citation statements)

References 53 publications

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“…Likewise, Cellulophaga lipid A also carries unsaturated acyl chains, which is known to be a characteristic adopted by bacteria to increment the outer membrane fluidity by decreasing the lipid packing [37] . Worth mentioning is also the high content of odd‐numbered (15 and 17 carbon atoms) and branched acyl chains of the Cellulophaga lipid A that was a characteristic often associated with other bacteria of the Bacteroidetes phylum [38–42] . Another peculiarity was the occurrence of hydroxylated acyl chains as secondary substituents of the reducing glucosamine, which in parallel supported the hypothesis of a 3+3 symmetry of the acyl chains in the hexa‐acylated lipid A forms that were detected as minor components of Cellulophaga LPS.…”

Section: Discussionmentioning

confidence: 88%

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

et al. 2023

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Marine bacteria, which are often described as chemical gold, are considered an exceptional source of new therapeutics. Considerable research interest has been given to lipopolysaccharides (LPSs), the main components of the Gram-negative outer membrane. LPS and its lipid A portion from marine bacteria are known to exhibit a tricky chemistry that has been often associated with intriguing properties such as behaving as immune adjuvants or anti-sepsis molecules. In this scenario, we report the structural determination of the lipid A from three marine bacteria within the Cellulophaga genus, which showed to produce an extremely heterogenous blend of tetra-to hexaacylated lipid A species, mostly carrying one phosphate and one D-mannose on the glucosamine disaccharide backbone. The ability of the three LPSs in activating TLR4 signaling revealed a weaker immunopotential by C. baltica NNO 15840 T and C. tyrosinoxydans EM41 T , while C. algicola ACAM 630 T behaved as a more potent TLR4 activator.

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Section: Discussionmentioning

confidence: 88%

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

et al. 2023

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Section: Discussionmentioning

confidence: 99%

“…One possibility is that the stably closed BtuBG complexes result from OM extraction and purification in detergent. It is conceivable that the LPS within the native OM environment, being highly negatively charged 33 , could destabilise the closed state to favour opening. Alternatively, BtuG lid opening could be a relatively rare event, given that the B 12 requirements of the cell are likely to be modest, contrasting with SusCD systems which mediate uptake of carbon sources.…”

Section: Discussionmentioning

confidence: 99%

BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B₁₂uptake in gutBacteroides

Abellón-Ruiz

Jana

Silale

et al. 2022

Preprint

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Vitamin B12 (cobalamin) is the most complex vitamin and essential for many human gut microbes. However, cobalamin is synthesised only by a limited number of bacteria, making many gut microbes dependent on scavenging to meet their cobalamin requirements. Since bacterial densities in the gut are extremely high, competition for cobalamin is severe, making it a keystone micronutrient that shapes human gut microbial communities. Contrasting with Enterobacteria like Escherichia coli which only have one outer membrane (OM) transporter dedicated to B12 uptake (BtuB), members of the dominant genus Bacteroides often encode several vitamin B12 OM transporters together with a conserved array of surface-exposed B12-binding lipoproteins. Here we show, via X-ray crystallography, cryogenic electron microscopy (cryoEM) and molecular dynamics (MD) simulations, that the BtuB1 and BtuB2 transporters from the prominent human gut bacterium Bacteroides thetaiotaomicron form stable complexes with the surface-exposed lipoproteins BtuG1 and BtuG2. The lipoproteins cap the external surface of their cognate BtuB transporter and, when open, capture B12 via electrostatic attraction. After B12 capture, the BtuG lid closes, with concomitant transfer of the vitamin to the BtuB transporter and subsequent transport. We propose that TonB-dependent, lipoprotein-assisted small molecule uptake is a general feature of Bacteroides spp. that is important for the success of this genus in colonising the human gut.

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“…As for the intact LOS, 1 mg/mL solution in distilled water was prepared and then mixed with DHB, which was suspended in 0.1% citric acid. 49 Finally, the mild acid hydrolysis product dissolved in distilled water was mixed with THAP in acetonitrile with 0.1% TFA (1:1). Each spectrum in the MS experiments was a result of the accumulation of 2000 laser shots, whereas 5000–7000 shots were summed for the MS/MS spectra.…”

Section: Methodsmentioning

confidence: 99%

“…The matrix solution was 2,4,6-trihydroxyacetophenone (THAP) in CH 3 OH/0.1% TFA/AcN (7:2:1, v/v) at a concentration of 75 mg/mL. As for the intact LOS, 1 mg/mL solution in distilled water was prepared and then mixed with DHB, which was suspended in 0.1% citric acid 49. Finally, the mild acid hydrolysis product dissolved in distilled water was mixed with THAP in acetonitrile with 0.1% TFA (1:1).…”

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confidence: 99%

Expanding Knowledge of Methylotrophic Capacity: Structure and Properties of the Rough-Type Lipopolysaccharide from Methylobacterium extorquens and Its Role on Membrane Resistance to Methanol

Lorenzo

Nicolardi

Marchetti

et al. 2023

JACS Au

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The ability of Methylobacterium extorquens to grow on methanol as the sole carbon and energy source has been the object of intense research activity. Unquestionably, the bacterial cell envelope serves as a defensive barrier against such an environmental stressor, with a decisive role played by the membrane lipidome, which is crucial for stress resistance. However, the chemistry and the function of the main constituent of the M. extorquens outer membrane, the lipopolysaccharide (LPS), is still undefined. Here, we show that M. extorquens produces a rough-type LPS with an uncommon, non-phosphorylated, and extensively O-methylated core oligosaccharide, densely substituted with negatively charged residues in the inner region, including novel monosaccharide derivatives such as O-methylated Kdo/Ko units. Lipid A is composed of a non-phosphorylated trisaccharide backbone with a distinctive, low acylation pattern; indeed, the sugar skeleton was decorated with three acyl moieties and a secondary very long chain fatty acid, in turn substituted by a 3-O-acetyl-butyrate residue. Spectroscopic, conformational, and biophysical analyses on M. extorquens LPS highlighted how structural and tridimensional features impact the molecular organization of the outer membrane. Furthermore, these chemical features also impacted and improved membrane resistance in the presence of methanol, thus regulating membrane ordering and dynamics.

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Bacteroides thetaiotaomicron rough-type lipopolysaccharide: The chemical structure and the immunological activity

Cited by 19 publications

References 53 publications

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B₁₂uptake in gutBacteroides

Expanding Knowledge of Methylotrophic Capacity: Structure and Properties of the Rough-Type Lipopolysaccharide from Methylobacterium extorquens and Its Role on Membrane Resistance to Methanol

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Bacteroides thetaiotaomicron rough-type lipopolysaccharide: The chemical structure and the immunological activity

Cited by 19 publications

References 53 publications

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

Pushing the Boundaries of Structural Heterogeneity with the Lipid A of Marine Bacteria Cellulophaga

BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B12uptake in gutBacteroides

Expanding Knowledge of Methylotrophic Capacity: Structure and Properties of the Rough-Type Lipopolysaccharide from Methylobacterium extorquens and Its Role on Membrane Resistance to Methanol

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BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B₁₂uptake in gutBacteroides