title: Differentiation of CC vs CXC chemokine dimers with GAG octasaccharide binding partners: an ion mobility mass spectrometry approach.
abstract: Chemokines, 8 kDa proteins implicated in leukocyte migration via oligomerization, bind to glycosaminoglycans (GAGs) during the inflammation response as a means to regulate chemokine migration. Structural characterization of chemokines non-covalently bound to GAGs provides physiologically meaningful data in regard to routine inmmunosurveillance and disease response. In order to analyze the structures resulting from the GAG:chemokine interaction, we employed ion mobility mass spectrometry (IMMS) to analyze monocyte chemoattractant protein-1 (MCP-1), a CC chemokine, and interleukin-8 (IL-8), a CXC chemokine, along with their individual interactions with GAG heparin octasaccharides. We show that MCP-1 and IL-8 are physiologically present as a dimer, with MCP-1 having two variants of its dimeric form and IL-8 having only one. We also show that the MCP-1 dimer adopts two conformations, one extended and one compact, when bound to a dodecasulfated heparin octasaccharide. Binding of MCP-1 to heparin octasaccharide isomers of varying sulfation patterns results in similar arrival time distribution values, which suggests minimal distinguishing features among the resultant complexes. Additionally, tandem mass spectrometry (MS/MS) showed that the binding of MCP-1 to a heparin octasaccharide has different dissociation patterns when compared with the corresponding IL-8 bound dimer. Overall, IMMS and MS/MS were used to better define the structural tendencies and differences associated with CC and CXC dimers when associated with GAG octasaccharides.
authors: Department of Chemistry, University of California, Davis, California 95616, USA.
authors: Youjin
authors: Y
authors: Seo
authors: Armann
authors: A
authors: Andaya
authors: Christian
authors: C
authors: Bleiholder
authors: Julie A
authors: JA
authors: Leary
mesh_terms: D018932:Chemokine CCL2 / Q000737:chemistry / Q000378:metabolism*; D006493:Heparin / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D016209:Interleukin-8 / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D053719:Tandem Mass Spectrometry
chemical_list: D018932:Chemokine CCL2; D016209:Interleukin-8; D006493:Heparin