Molecular basis of chemokine CXCL5-glycosaminoglycan interactions

Krishna Mohan Sepuru, Balaji Nagarajan, Umesh R. Desai, Krishna Rajarathnam

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Chemokines, a large family of highly versatile small soluble proteins, play crucial roles in defining innate and adaptive immune responses by regulating the trafficking of leukocytes, and also play a key role in various aspects of human physiology. Chemokines share the characteristic feature of reversibly existing as monomers and dimers, and their functional response is intimately coupled to interaction with glycosaminoglycans (GAGs). Currently, nothing is known regarding the structural basis or molecular mechanisms underlying CXCL5-GAG interactions. To address this missing knowledge, we characterized the interaction of a panel of heparin oligosaccharides to CXCL5 using solution NMR, isothermal titration calorimetry, and molecular dynamics simulations. NMR studies indicated that the dimer is the high-affinity GAG binding ligand and that lysine residues from the N-loop, 40s turn, β3 strand, and C-terminal helix mediate binding. Isothermal titration calorimetry indicated a stoichiometry of two oligosaccharides per CXCL5 dimer. NMR-based structural models reveal that these residues form a contiguous surface within a monomer and, interestingly, that the GAG-binding domain overlaps with the receptor-binding domain, indicating that a GAG-bound chemokine cannot activate the receptor. Molecular dynamics simulations indicate that the roles of the individual lysines are not equivalent and that helical lysines play a more prominent role in determining binding geometry and affinity. Further, binding interactions and GAG geometry in CXCL5 are novel and distinctly different compared with the related chemokines CXCL1 and CXCL8. We conclude that a finely tuned balance between the GAG-bound dimer and free soluble monomer regulates CXCL5-mediated receptor signaling and function.

Original languageEnglish (US)
Pages (from-to)20539-20550
Number of pages12
JournalJournal of Biological Chemistry
Volume291
Issue number39
DOIs
StatePublished - Sep 23 2016

Fingerprint

Chemokine CXCL5
Glycosaminoglycans
Dimers
Chemokines
Lysine
Calorimetry
Monomers
Nuclear magnetic resonance
Molecular Dynamics Simulation
Oligosaccharides
Titration
Molecular dynamics
Chemokine CXCL1
Geometry
Structural Models
Physiology
Computer simulation
Adaptive Immunity
Interleukin-8
Innate Immunity

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Molecular basis of chemokine CXCL5-glycosaminoglycan interactions. / Sepuru, Krishna Mohan; Nagarajan, Balaji; Desai, Umesh R.; Rajarathnam, Krishna.

In: Journal of Biological Chemistry, Vol. 291, No. 39, 23.09.2016, p. 20539-20550.

Research output: Contribution to journalArticle

Sepuru, Krishna Mohan ; Nagarajan, Balaji ; Desai, Umesh R. ; Rajarathnam, Krishna. / Molecular basis of chemokine CXCL5-glycosaminoglycan interactions. In: Journal of Biological Chemistry. 2016 ; Vol. 291, No. 39. pp. 20539-20550.
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