Structural basis for differential binding of the interleukin-8 monomer and dimer to the CXCR1 N-domain: Role of coupled interactions and dynamics

Aishwarya Ravindran, Prem Raj B Joseph, Krishna Rajarathnam

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Interleukin-8 (IL-8 or CXCL8) plays a critical role in orchestrating the immune response by binding and activating the receptor CXCR1 that belongs to the GPCR class. IL-8 exists as both monomers and dimers, and both bind CXCR1 but with differential affinities. It is well established that the monomer is the high-affinity ligand and that the interactions between the ligand N-loop and receptor N-domain play a critical role in determining binding affinity. In order to characterize the structural basis of differential binding of the IL-8 monomer and dimer to the CXCR1 N-domain, we analyzed binding-induced NMR chemical shift and peak intensity changes and show that they are exquisitely sensitive and can provide detailed insights into the binding process. We used three IL-8 variants, a designed monomer, a trapped disulfide-linked dimer, and WT at dimeric concentrations. NMR data for the monomer show that nonsequential residues that span the entire N-loop are involved in the binding process and that the binding is mediated by a network of extensive direct and indirect coupled interactions. Interestingly, in the case of WT, binding induces dissociation of the dimer-receptor complex to the monomer-receptor complex, and in the case of the trapped dimer, binding results in increased global conformational flexibility. Increased dynamics is evidence of unfavorable interactions, indicating that binding of the WT dimer triggers conformational changes that disrupt dimer-interface interactions, resulting in its dissociation. These results together provide evidence that binding is not a localized event but results in extensive coupled interactions within the monomer and across the dimer interface and that these interactions play a fundamental role in determining binding affinity.

Original languageEnglish (US)
Pages (from-to)8795-8805
Number of pages11
JournalBiochemistry
Volume48
Issue number37
DOIs
StatePublished - Sep 22 2009

Fingerprint

Interleukin-8
Dimers
Monomers
Interleukin-8A Receptors
Ligands
Disulfides
Nuclear magnetic resonance
Chemical shift

ASJC Scopus subject areas

  • Biochemistry

Cite this

Structural basis for differential binding of the interleukin-8 monomer and dimer to the CXCR1 N-domain : Role of coupled interactions and dynamics. / Ravindran, Aishwarya; Joseph, Prem Raj B; Rajarathnam, Krishna.

In: Biochemistry, Vol. 48, No. 37, 22.09.2009, p. 8795-8805.

Research output: Contribution to journalArticle

@article{2551463a6c674eb782c1dcd27919c89d,
title = "Structural basis for differential binding of the interleukin-8 monomer and dimer to the CXCR1 N-domain: Role of coupled interactions and dynamics",
abstract = "Interleukin-8 (IL-8 or CXCL8) plays a critical role in orchestrating the immune response by binding and activating the receptor CXCR1 that belongs to the GPCR class. IL-8 exists as both monomers and dimers, and both bind CXCR1 but with differential affinities. It is well established that the monomer is the high-affinity ligand and that the interactions between the ligand N-loop and receptor N-domain play a critical role in determining binding affinity. In order to characterize the structural basis of differential binding of the IL-8 monomer and dimer to the CXCR1 N-domain, we analyzed binding-induced NMR chemical shift and peak intensity changes and show that they are exquisitely sensitive and can provide detailed insights into the binding process. We used three IL-8 variants, a designed monomer, a trapped disulfide-linked dimer, and WT at dimeric concentrations. NMR data for the monomer show that nonsequential residues that span the entire N-loop are involved in the binding process and that the binding is mediated by a network of extensive direct and indirect coupled interactions. Interestingly, in the case of WT, binding induces dissociation of the dimer-receptor complex to the monomer-receptor complex, and in the case of the trapped dimer, binding results in increased global conformational flexibility. Increased dynamics is evidence of unfavorable interactions, indicating that binding of the WT dimer triggers conformational changes that disrupt dimer-interface interactions, resulting in its dissociation. These results together provide evidence that binding is not a localized event but results in extensive coupled interactions within the monomer and across the dimer interface and that these interactions play a fundamental role in determining binding affinity.",
author = "Aishwarya Ravindran and Joseph, {Prem Raj B} and Krishna Rajarathnam",
year = "2009",
month = "9",
day = "22",
doi = "10.1021/bi901194p",
language = "English (US)",
volume = "48",
pages = "8795--8805",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "37",

}

TY - JOUR

T1 - Structural basis for differential binding of the interleukin-8 monomer and dimer to the CXCR1 N-domain

T2 - Role of coupled interactions and dynamics

AU - Ravindran, Aishwarya

AU - Joseph, Prem Raj B

AU - Rajarathnam, Krishna

PY - 2009/9/22

Y1 - 2009/9/22

N2 - Interleukin-8 (IL-8 or CXCL8) plays a critical role in orchestrating the immune response by binding and activating the receptor CXCR1 that belongs to the GPCR class. IL-8 exists as both monomers and dimers, and both bind CXCR1 but with differential affinities. It is well established that the monomer is the high-affinity ligand and that the interactions between the ligand N-loop and receptor N-domain play a critical role in determining binding affinity. In order to characterize the structural basis of differential binding of the IL-8 monomer and dimer to the CXCR1 N-domain, we analyzed binding-induced NMR chemical shift and peak intensity changes and show that they are exquisitely sensitive and can provide detailed insights into the binding process. We used three IL-8 variants, a designed monomer, a trapped disulfide-linked dimer, and WT at dimeric concentrations. NMR data for the monomer show that nonsequential residues that span the entire N-loop are involved in the binding process and that the binding is mediated by a network of extensive direct and indirect coupled interactions. Interestingly, in the case of WT, binding induces dissociation of the dimer-receptor complex to the monomer-receptor complex, and in the case of the trapped dimer, binding results in increased global conformational flexibility. Increased dynamics is evidence of unfavorable interactions, indicating that binding of the WT dimer triggers conformational changes that disrupt dimer-interface interactions, resulting in its dissociation. These results together provide evidence that binding is not a localized event but results in extensive coupled interactions within the monomer and across the dimer interface and that these interactions play a fundamental role in determining binding affinity.

AB - Interleukin-8 (IL-8 or CXCL8) plays a critical role in orchestrating the immune response by binding and activating the receptor CXCR1 that belongs to the GPCR class. IL-8 exists as both monomers and dimers, and both bind CXCR1 but with differential affinities. It is well established that the monomer is the high-affinity ligand and that the interactions between the ligand N-loop and receptor N-domain play a critical role in determining binding affinity. In order to characterize the structural basis of differential binding of the IL-8 monomer and dimer to the CXCR1 N-domain, we analyzed binding-induced NMR chemical shift and peak intensity changes and show that they are exquisitely sensitive and can provide detailed insights into the binding process. We used three IL-8 variants, a designed monomer, a trapped disulfide-linked dimer, and WT at dimeric concentrations. NMR data for the monomer show that nonsequential residues that span the entire N-loop are involved in the binding process and that the binding is mediated by a network of extensive direct and indirect coupled interactions. Interestingly, in the case of WT, binding induces dissociation of the dimer-receptor complex to the monomer-receptor complex, and in the case of the trapped dimer, binding results in increased global conformational flexibility. Increased dynamics is evidence of unfavorable interactions, indicating that binding of the WT dimer triggers conformational changes that disrupt dimer-interface interactions, resulting in its dissociation. These results together provide evidence that binding is not a localized event but results in extensive coupled interactions within the monomer and across the dimer interface and that these interactions play a fundamental role in determining binding affinity.

UR - http://www.scopus.com/inward/record.url?scp=70349146698&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=70349146698&partnerID=8YFLogxK

U2 - 10.1021/bi901194p

DO - 10.1021/bi901194p

M3 - Article

C2 - 19681642

AN - SCOPUS:70349146698

VL - 48

SP - 8795

EP - 8805

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 37

ER -