Document Detail


From agonist to antagonist: structure and dynamics of innate immune glycoprotein MD-2 upon recognition of variably acylated bacterial endotoxins.
MedLine Citation:
PMID:  21924775     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The human immune response to an infection by Gram-negative bacteria involves detection of lipopolysaccharides (LPS), also known as endotoxins, which comprise the bacterial outer cell wall. Distinct from mammalian glycolipid structures, LPS have a conserved chemical pattern that is recognized by the pattern recognition receptor complex formed by myeloid differentiation protein 2 (MD-2) and toll-like receptor 4 (TLR4). A remarkable immune-mediated structure-toxicity relationship has been defined that relates to the number of acyl chains in the endotoxin. While there is a clear correlation between endotoxin acylation and elicited agonist or antagonist responses, the 3D structural basis of this relationship remains unclear. In order to explore, at atomic-resolution, the effects of a range of chemically distinct endotoxins on the structure and dynamics of their MD-2·endotoxin complexes, we examined a series of variably acylated lipid A molecules from Escherichia coli and Neisseria meningitidis in complex with human MD-2. Through the application of molecular dynamics simulations, in concert with experimental data, we have identified specific structural and dynamic features of the MD-2-endotoxin complexes that may control dimerization of TLR4 molecules. As dimerization is central to the release of downstream chemical mediators, the results provide a structural foundation for the ability of endotoxins to act as either agonists or antagonists of the TLR4 pathway.
Authors:
Mari L DeMarco; Robert J Woods
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2011-09-16
Journal Detail:
Title:  Molecular immunology     Volume:  49     ISSN:  1872-9142     ISO Abbreviation:  Mol. Immunol.     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-10-31     Completed Date:  2011-12-20     Revised Date:  2012-01-06    
Medline Journal Info:
Nlm Unique ID:  7905289     Medline TA:  Mol Immunol     Country:  England    
Other Details:
Languages:  eng     Pagination:  124-33     Citation Subset:  IM    
Copyright Information:
Published by Elsevier Ltd.
Affiliation:
Complex Carbohydrate Research Center, University of Georgia, GA 30602, USA. mdemarco@wustl.edu
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MeSH Terms
Descriptor/Qualifier:
Acylation
Humans
Immunity, Innate / immunology
Lipid A / chemistry*,  immunology*,  metabolism
Lymphocyte Antigen 96 / chemistry*,  immunology*,  metabolism
Models, Molecular
Protein Structure, Quaternary
Protein Structure, Secondary
Protein Structure, Tertiary
Toll-Like Receptor 4 / chemistry*,  immunology,  metabolism
Grant Support
ID/Acronym/Agency:
5R01GM055230/GM/NIGMS NIH HHS; P41 RR005351-15/RR/NCRR NIH HHS; RR05351/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
0/LY96 protein, human; 0/Lipid A; 0/Lymphocyte Antigen 96; 0/TLR4 protein, human; 0/Toll-Like Receptor 4

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