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Molecular Characterization of Lipopolysaccharide Binding to Human α-1-Acid Glycoprotein.

Huang JX, Azad MA, Yuriev E, Baker MA, Nation RL, Li J, Cooper MA, Velkov T - J Lipids (2012)

Bottom Line: The ability of AGP to bind circulating lipopolysaccharide (LPS) in plasma is believed to help reduce the proinflammatory effect of bacterial lipid A molecules.In order to dissect the contribution of the lipid A, core oligosaccharide and O-antigen polysaccharide components of LPS, the AGP binding affinity of LPS from smooth strains, were compared to lipid A, Kdo2-lipid A, R(a), R(d), and R(e) rough LPS mutants.The SAR analysis enabled by the binding data suggested that, in addition to the important role played by the lipid A and core components of LPS, it is predominately the unique species- and strain-specific carbohydrate structure of the O-antigen polysaccharide that largely determines the binding affinity for AGP.

View Article: PubMed Central - PubMed

Affiliation: Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St. Lucia, QLD 4072, Australia.

ABSTRACT
The ability of AGP to bind circulating lipopolysaccharide (LPS) in plasma is believed to help reduce the proinflammatory effect of bacterial lipid A molecules. Here, for the first time we have characterized human AGP binding characteristics of the LPS from a number of pathogenic Gram-negative bacteria: Escherichia coli, Salmonella typhimurium, Klebsiella pneumonia, Pseudomonas aeruginosa, and Serratia marcescens. The binding affinity and structure activity relationships (SAR) of the AGP-LPS interactions were characterized by surface plasma resonance (SPR). In order to dissect the contribution of the lipid A, core oligosaccharide and O-antigen polysaccharide components of LPS, the AGP binding affinity of LPS from smooth strains, were compared to lipid A, Kdo2-lipid A, R(a), R(d), and R(e) rough LPS mutants. The SAR analysis enabled by the binding data suggested that, in addition to the important role played by the lipid A and core components of LPS, it is predominately the unique species- and strain-specific carbohydrate structure of the O-antigen polysaccharide that largely determines the binding affinity for AGP. Together, these data are consistent with the role of AGP in the binding and transport of LPS in plasma during acute-phase inflammatory responses to invading Gram-negative bacteria.

No MeSH data available.


Related in: MedlinePlus

Fluorescence emission spectra of (1) FITC-labeled E. coli O111:B4 LPS (5 μM). (2) Decrease in fluorescence observed upon addition of chlorpromazine (20 μM) to the FITC-LPS:AGP complex. (3) FITC-LPS (5 μM) in complex with human AGP (25 μM). (4) FITC-LPS (5 μM) in complex with human AGP (25 μM) in the presence of EDTA (1 mM).
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fig2: Fluorescence emission spectra of (1) FITC-labeled E. coli O111:B4 LPS (5 μM). (2) Decrease in fluorescence observed upon addition of chlorpromazine (20 μM) to the FITC-LPS:AGP complex. (3) FITC-LPS (5 μM) in complex with human AGP (25 μM). (4) FITC-LPS (5 μM) in complex with human AGP (25 μM) in the presence of EDTA (1 mM).

Mentions: FITC-LPS displays a fluorescence emission maximum as a wavelength of ~515 nm (Figure 2). Fluorescence intensity was noted to increase upon titration with AGP (Figure 2). EDTA has a well-documented effect of sequestering the divalent cations that help bridge adjacent LPS molecules when they are arranged in a leaflet or aggregate structure [9]. The titration of FITC-LPS with AGP in the presence of EDTA (1 mM final concentration) produced a higher level of fluorescence emission compared to an identical titration in the absence of EDTA (Figure 2). The addition of chlorpromazine (20 μM final concentration) to the FITC-LPS:AGP complex produced a decrease in fluorescence emission (Figure 2).


Molecular Characterization of Lipopolysaccharide Binding to Human α-1-Acid Glycoprotein.

Huang JX, Azad MA, Yuriev E, Baker MA, Nation RL, Li J, Cooper MA, Velkov T - J Lipids (2012)

Fluorescence emission spectra of (1) FITC-labeled E. coli O111:B4 LPS (5 μM). (2) Decrease in fluorescence observed upon addition of chlorpromazine (20 μM) to the FITC-LPS:AGP complex. (3) FITC-LPS (5 μM) in complex with human AGP (25 μM). (4) FITC-LPS (5 μM) in complex with human AGP (25 μM) in the presence of EDTA (1 mM).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539403&req=5

fig2: Fluorescence emission spectra of (1) FITC-labeled E. coli O111:B4 LPS (5 μM). (2) Decrease in fluorescence observed upon addition of chlorpromazine (20 μM) to the FITC-LPS:AGP complex. (3) FITC-LPS (5 μM) in complex with human AGP (25 μM). (4) FITC-LPS (5 μM) in complex with human AGP (25 μM) in the presence of EDTA (1 mM).
Mentions: FITC-LPS displays a fluorescence emission maximum as a wavelength of ~515 nm (Figure 2). Fluorescence intensity was noted to increase upon titration with AGP (Figure 2). EDTA has a well-documented effect of sequestering the divalent cations that help bridge adjacent LPS molecules when they are arranged in a leaflet or aggregate structure [9]. The titration of FITC-LPS with AGP in the presence of EDTA (1 mM final concentration) produced a higher level of fluorescence emission compared to an identical titration in the absence of EDTA (Figure 2). The addition of chlorpromazine (20 μM final concentration) to the FITC-LPS:AGP complex produced a decrease in fluorescence emission (Figure 2).

Bottom Line: The ability of AGP to bind circulating lipopolysaccharide (LPS) in plasma is believed to help reduce the proinflammatory effect of bacterial lipid A molecules.In order to dissect the contribution of the lipid A, core oligosaccharide and O-antigen polysaccharide components of LPS, the AGP binding affinity of LPS from smooth strains, were compared to lipid A, Kdo2-lipid A, R(a), R(d), and R(e) rough LPS mutants.The SAR analysis enabled by the binding data suggested that, in addition to the important role played by the lipid A and core components of LPS, it is predominately the unique species- and strain-specific carbohydrate structure of the O-antigen polysaccharide that largely determines the binding affinity for AGP.

View Article: PubMed Central - PubMed

Affiliation: Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St. Lucia, QLD 4072, Australia.

ABSTRACT
The ability of AGP to bind circulating lipopolysaccharide (LPS) in plasma is believed to help reduce the proinflammatory effect of bacterial lipid A molecules. Here, for the first time we have characterized human AGP binding characteristics of the LPS from a number of pathogenic Gram-negative bacteria: Escherichia coli, Salmonella typhimurium, Klebsiella pneumonia, Pseudomonas aeruginosa, and Serratia marcescens. The binding affinity and structure activity relationships (SAR) of the AGP-LPS interactions were characterized by surface plasma resonance (SPR). In order to dissect the contribution of the lipid A, core oligosaccharide and O-antigen polysaccharide components of LPS, the AGP binding affinity of LPS from smooth strains, were compared to lipid A, Kdo2-lipid A, R(a), R(d), and R(e) rough LPS mutants. The SAR analysis enabled by the binding data suggested that, in addition to the important role played by the lipid A and core components of LPS, it is predominately the unique species- and strain-specific carbohydrate structure of the O-antigen polysaccharide that largely determines the binding affinity for AGP. Together, these data are consistent with the role of AGP in the binding and transport of LPS in plasma during acute-phase inflammatory responses to invading Gram-negative bacteria.

No MeSH data available.


Related in: MedlinePlus