Mutational analysis of the fractalkine chemokine domain. Basic amino acid residues differentially contribute to CX3CR1 binding, signaling, and cell adhesion.

Published

Journal Article

Fractalkine (FKN/CX3CL1) is a unique member of the chemokine gene family and contains a chemokine domain (CD), a mucin-like stalk, a single transmembrane region, and a short intracellular C terminus. This structural distinction affords FKN the property of mediating capture and firm adhesion of FKN receptor (CX3CR1)-expressing cells under physiological flow conditions. Shed forms of FKN also exist, and these promote chemotaxis of CX3CR1-expressing leukocytes. The goal of the present study was to identify specific residues within the FKN-CD critical for FKN-CX3CR1 interactions. Two residues were identified in the FKN-CD, namely Lys-7 and Arg-47, that are important determinants in mediating an FKN-CX3CR1 interaction. FKN-K7A and FKN-R47A mutants exhibited 30-60-fold decreases in affinity for CX3CR1 and failed to arrest efficiently CX3CR1-expressing cells under physiological flow conditions. However, these mutants had differential effects on chemotaxis of CX3CR1-expressing cells. The FKN-K7A mutant acted as an equipotent partial agonist, whereas the FKN-R47A mutant had marked decreased potency and efficacy in measures of chemotactic activity. These data identify specific structural features of the FKN-CD that are important in interactions with CX3CR1 including steady state binding, signaling, and firm adhesion of CX3CR1-expressing cells.

Full Text

Duke Authors

Cited Authors

  • Harrison, JK; Fong, AM; Swain, PA; Chen, S; Yu, YR; Salafranca, MN; Greenleaf, WB; Imai, T; Patel, DD

Published Date

  • June 15, 2001

Published In

Volume / Issue

  • 276 / 24

Start / End Page

  • 21632 - 21641

PubMed ID

  • 11278650

Pubmed Central ID

  • 11278650

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M010261200

Language

  • eng

Conference Location

  • United States