Open AccessBiophysical analysis of the interaction of the serum protein human β 2 GPI with bacterial lipopolysaccharide
Author(s) -
Gries Anna,
Prassl Ruth,
Fukuoka Satoshi,
Rössle Manfred,
Kaconis Yani,
Heinbockel Lena,
Gutsmann Thomas,
Brandenburg Klaus
Publication year - 2014
Publication title -
febs open bio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.718
H-Index - 31
ISSN - 2211-5463
DOI - 10.1016/j.fob.2014.04.008
Subject(s) - lipopolysaccharide , phosphatidylserine , chemistry , immune system , glycoprotein , lipid a , in vitro , phospholipid , biochemistry , microbiology and biotechnology , biology , immunology , membrane
There are several human serum proteins for which no clear role is yet known. Among these is the abundant serum protein beta2‐glycoprotein‐I (β 2 GPI), which is known to bind to negatively charged phospholipids as well as to bacterial lipopolysaccharides (LPS), and was therefore proposed to play a role in the immune response. To understand the details of these interactions, a biophysical analysis of the binding of β 2 GPI to LPS and phosphatidylserine (PS) was performed. The data indicate only a moderate tendency of the protein (1) to influence the LPS‐induced cytokine production in vitro , (2) to react exothermally with LPS in a non‐saturable way, and (3) to change its local microenvironment upon LPS association. Additionally, we found that the protein binds more strongly to phosphatidylserine (PS) than to LPS. Furthermore, β 2 GPI converts the LPS bilayer aggregates into a stronger multilamellar form, and reduces the fluidity of the hydrocarbon moiety of LPS due to a rigidification of the acyl chains. From these data it can be concluded that β 2 GPI plays a role as an immune‐modulating agent, but there is much less evidence for a role in immune defense against bacterial toxins such as LPS.