CXCL1/MGSA Is a novel glycosaminoglycan (GAG)-binding chemokine

Structural evidence for two distinct non-overlapping binding domains

Krishna Mohan Sepuru, Krishna Rajarathnam

    Research output: Contribution to journalArticle

    25 Citations (Scopus)

    Abstract

    In humans, the chemokine CXCL1/MGSA (hCXCL1) plays fundamental and diverse roles in pathophysiology, from microbial killing to cancer progression, by orchestrating the directed migration of immune and non-immune cells. Cellular trafficking is highly regulated and requires concentration gradients that are achieved by interactions with sulfated glycosaminoglycans (GAGs). However, very little is known regarding the structural basis underlying hCXCL1-GAG interactions.Weaddressed this by characterizing the binding of GAG heparin oligosaccharides to hCXCL1 using NMR spectroscopy. Binding experiments under conditions at which hCXCL1 exists as monomers and dimers indicate that the dimer is the high-affinity GAG ligand. NMRexperiments and modeling studies indicate that lysine and arginine residues mediate binding and that they are located in two non-overlapping domains. One domain, consisting of N-loop and C-helical residues (defined as α-domain) has also been identified previously as the GAG-binding domain for the related chemokine CXCL8/IL-8. The second domain, consisting of residues from the N terminus, 40s turn, and third β-strand (defined as β-domain) is novel. Eliminating β-domain binding by mutagenesis does not perturb α-domain binding, indicating two independent GAG-binding sites. It is known that N-loop and N-terminal residues mediate receptor activation, and we show that these residues are also involved in extensive GAG interactions. We also show that the GAG-bound hCXCL1 completely occlude receptor binding. We conclude that hCXCL1- GAG interactions provide stringent control over regulating chemokine levels and receptor accessibility and activation, and that chemotactic gradients mediate cellular trafficking to the target site.

    Original languageEnglish (US)
    Pages (from-to)4247-4255
    Number of pages9
    JournalJournal of Biological Chemistry
    Volume291
    Issue number8
    DOIs
    StatePublished - Feb 19 2016

    Fingerprint

    Chemokine CXCL1
    Glycosaminoglycans
    Chemokines
    A73025
    Interleukin-8
    Dimers
    Chemical activation
    Mutagenesis
    Chemokine Receptors
    Oligosaccharides
    Nuclear magnetic resonance spectroscopy
    Lysine
    Arginine
    Heparin
    Magnetic Resonance Spectroscopy
    Monomers
    Binding Sites
    Ligands

    ASJC Scopus subject areas

    • Biochemistry
    • Cell Biology
    • Molecular Biology

    Cite this

    CXCL1/MGSA Is a novel glycosaminoglycan (GAG)-binding chemokine : Structural evidence for two distinct non-overlapping binding domains. / Sepuru, Krishna Mohan; Rajarathnam, Krishna.

    In: Journal of Biological Chemistry, Vol. 291, No. 8, 19.02.2016, p. 4247-4255.

    Research output: Contribution to journalArticle

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