Thermodynamic characterization of interleukin-8 monomer binding to CXCR1 receptor N-terminal domain

Harshica Fernando, Gregg Thomas Nagle, Krishna Rajarathnam

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Chemokines elicit their function by binding receptors of the G-protein-coupled receptor class, and the N-terminal domain (N-domain) of the receptor is one of the two critical ligand-binding sites. In this study, the thermodynamic basis for binding of the chemokine interleukin-8 (IL-8) to the N-domain of its receptor CXCR1 was characterized using isothermal titration calorimetry. We have shown previously that only the monomer of IL-8, and not the dimer, functions as a high-affinity ligand, so in this study we used the IL-8(1-66) deletion mutant which exists as a monomer. Calorimetry data indicate that the binding is enthalpically favored and entropically disfavored, and a negative heat capacity change indicates burial of hydrophobic residues in the complex. A characteristic feature of chemokine receptor N-domains is the large number of acidic residues, and experiments using different buffers show no net proton transfer, indicating that the CXCR1 N-domain acidic residues are not protonated in the binding process. CXCR1 N-domain peptide is unstructured in the free form but adopts a more defined structure in the bound form, and so binding is coupled to induction of the structure of the N-domain. Measurements in the presence of the osmolyte, trimethylamine N-oxide, which induces the structure of unfolded proteins, show that formation of the coupled N-domain structure involves only small ΔH and ΔS changes. These results together indicate that the binding is driven by packing interactions in the complex that are enthalpically favored, and are consistent with the observation that the N-domain binds in an extended form and interacts with multiple IL-8 N-loop residues over a large surface area.

Original languageEnglish (US)
Pages (from-to)241-251
Number of pages11
JournalFEBS Journal
Volume274
Issue number1
DOIs
StatePublished - Jan 1 2007

Fingerprint

Interleukin-8A Receptors
Interleukin-8
Thermodynamics
Monomers
Calorimetry
Chemokines
Ligands
Burial
Protein Unfolding
Proton transfer
Chemokine Receptors
G-Protein-Coupled Receptors
Titration
Interleukin-1
Dimers
Specific heat
Protons
Buffers
Hot Temperature
Binding Sites

Keywords

  • Interleukin-8
  • Isothermal titration calorimetry
  • Monomer
  • N-terminal domain
  • Thermodynamics

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Thermodynamic characterization of interleukin-8 monomer binding to CXCR1 receptor N-terminal domain. / Fernando, Harshica; Nagle, Gregg Thomas; Rajarathnam, Krishna.

In: FEBS Journal, Vol. 274, No. 1, 01.01.2007, p. 241-251.

Research output: Contribution to journalArticle

Fernando, Harshica ; Nagle, Gregg Thomas ; Rajarathnam, Krishna. / Thermodynamic characterization of interleukin-8 monomer binding to CXCR1 receptor N-terminal domain. In: FEBS Journal. 2007 ; Vol. 274, No. 1. pp. 241-251.
@article{00d52b8f176b4bbda518d904511f58af,
title = "Thermodynamic characterization of interleukin-8 monomer binding to CXCR1 receptor N-terminal domain",
abstract = "Chemokines elicit their function by binding receptors of the G-protein-coupled receptor class, and the N-terminal domain (N-domain) of the receptor is one of the two critical ligand-binding sites. In this study, the thermodynamic basis for binding of the chemokine interleukin-8 (IL-8) to the N-domain of its receptor CXCR1 was characterized using isothermal titration calorimetry. We have shown previously that only the monomer of IL-8, and not the dimer, functions as a high-affinity ligand, so in this study we used the IL-8(1-66) deletion mutant which exists as a monomer. Calorimetry data indicate that the binding is enthalpically favored and entropically disfavored, and a negative heat capacity change indicates burial of hydrophobic residues in the complex. A characteristic feature of chemokine receptor N-domains is the large number of acidic residues, and experiments using different buffers show no net proton transfer, indicating that the CXCR1 N-domain acidic residues are not protonated in the binding process. CXCR1 N-domain peptide is unstructured in the free form but adopts a more defined structure in the bound form, and so binding is coupled to induction of the structure of the N-domain. Measurements in the presence of the osmolyte, trimethylamine N-oxide, which induces the structure of unfolded proteins, show that formation of the coupled N-domain structure involves only small ΔH and ΔS changes. These results together indicate that the binding is driven by packing interactions in the complex that are enthalpically favored, and are consistent with the observation that the N-domain binds in an extended form and interacts with multiple IL-8 N-loop residues over a large surface area.",
keywords = "Interleukin-8, Isothermal titration calorimetry, Monomer, N-terminal domain, Thermodynamics",
author = "Harshica Fernando and Nagle, {Gregg Thomas} and Krishna Rajarathnam",
year = "2007",
month = "1",
day = "1",
doi = "10.1111/j.1742-4658.2006.05579.x",
language = "English (US)",
volume = "274",
pages = "241--251",
journal = "FEBS Journal",
issn = "1742-464X",
publisher = "Wiley-Blackwell",
number = "1",

}

TY - JOUR

T1 - Thermodynamic characterization of interleukin-8 monomer binding to CXCR1 receptor N-terminal domain

AU - Fernando, Harshica

AU - Nagle, Gregg Thomas

AU - Rajarathnam, Krishna

PY - 2007/1/1

Y1 - 2007/1/1

N2 - Chemokines elicit their function by binding receptors of the G-protein-coupled receptor class, and the N-terminal domain (N-domain) of the receptor is one of the two critical ligand-binding sites. In this study, the thermodynamic basis for binding of the chemokine interleukin-8 (IL-8) to the N-domain of its receptor CXCR1 was characterized using isothermal titration calorimetry. We have shown previously that only the monomer of IL-8, and not the dimer, functions as a high-affinity ligand, so in this study we used the IL-8(1-66) deletion mutant which exists as a monomer. Calorimetry data indicate that the binding is enthalpically favored and entropically disfavored, and a negative heat capacity change indicates burial of hydrophobic residues in the complex. A characteristic feature of chemokine receptor N-domains is the large number of acidic residues, and experiments using different buffers show no net proton transfer, indicating that the CXCR1 N-domain acidic residues are not protonated in the binding process. CXCR1 N-domain peptide is unstructured in the free form but adopts a more defined structure in the bound form, and so binding is coupled to induction of the structure of the N-domain. Measurements in the presence of the osmolyte, trimethylamine N-oxide, which induces the structure of unfolded proteins, show that formation of the coupled N-domain structure involves only small ΔH and ΔS changes. These results together indicate that the binding is driven by packing interactions in the complex that are enthalpically favored, and are consistent with the observation that the N-domain binds in an extended form and interacts with multiple IL-8 N-loop residues over a large surface area.

AB - Chemokines elicit their function by binding receptors of the G-protein-coupled receptor class, and the N-terminal domain (N-domain) of the receptor is one of the two critical ligand-binding sites. In this study, the thermodynamic basis for binding of the chemokine interleukin-8 (IL-8) to the N-domain of its receptor CXCR1 was characterized using isothermal titration calorimetry. We have shown previously that only the monomer of IL-8, and not the dimer, functions as a high-affinity ligand, so in this study we used the IL-8(1-66) deletion mutant which exists as a monomer. Calorimetry data indicate that the binding is enthalpically favored and entropically disfavored, and a negative heat capacity change indicates burial of hydrophobic residues in the complex. A characteristic feature of chemokine receptor N-domains is the large number of acidic residues, and experiments using different buffers show no net proton transfer, indicating that the CXCR1 N-domain acidic residues are not protonated in the binding process. CXCR1 N-domain peptide is unstructured in the free form but adopts a more defined structure in the bound form, and so binding is coupled to induction of the structure of the N-domain. Measurements in the presence of the osmolyte, trimethylamine N-oxide, which induces the structure of unfolded proteins, show that formation of the coupled N-domain structure involves only small ΔH and ΔS changes. These results together indicate that the binding is driven by packing interactions in the complex that are enthalpically favored, and are consistent with the observation that the N-domain binds in an extended form and interacts with multiple IL-8 N-loop residues over a large surface area.

KW - Interleukin-8

KW - Isothermal titration calorimetry

KW - Monomer

KW - N-terminal domain

KW - Thermodynamics

UR - http://www.scopus.com/inward/record.url?scp=33845599535&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33845599535&partnerID=8YFLogxK

U2 - 10.1111/j.1742-4658.2006.05579.x

DO - 10.1111/j.1742-4658.2006.05579.x

M3 - Article

VL - 274

SP - 241

EP - 251

JO - FEBS Journal

JF - FEBS Journal

SN - 1742-464X

IS - 1

ER -