Identification of lipopolysaccharide binding site on High Mobility Group Box 1 Protein (98.23)

Abstract

Abstract Lipopolysaccharide (LPS), a bacterial endotoxin, triggers deleterious systemic inflammatory responses when released into blood circulation, causing severe sepsis, organ dysfunction and death. LPS binding components in serum play an important role in modifying LPS toxicity by facilitating its interaction with the LPS signaling receptor, which is expressed on LPS-responsive cells. We have previously shown that HMGB1 is able to bind LPS and this binding can increase LPS-induced TNF-α production in human peripheral blood monocytes. In this report, we identified several LPS binding regions within human HMGB1 sequence by pull-down experiments with synthetic biotinylated peptide derived from HMGB1. Using a conventional sequence-based comparison with several other LPS-binding proteins, we identified similar LPS-binding motifs in LPS-binding peptides from HMGB1, but inhibition assay demonstrated that the capacity of these peptides to interfere with LPS-HMGB1 interaction exhibits different characteristics We are now carrying out further experiments to evaluate which amino acid residues contribute to LPS binding and functional differences between different peptide in LPS-binding capacities. Our studies identified a defined region of HMGB1 involved in LPS binding, thereby implicating a physiological role of human HMGB1 as an LPS-binding protein. [This study was supported by a grant from the Korean Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (A080694) and Brain Korea 21 project to Medical Science.]