title: The N-terminal region of the atypical chemokine receptor ACKR2 is a key determinant of ligand binding.
abstract: The atypical chemokine receptor, ACKR2 is a pivotal regulator of chemokine-driven inflammatory responses and works by binding, internalizing, and degrading inflammatory CC-chemokines. ACKR2 displays promiscuity of ligand binding and is capable of interacting with up to 14 different inflammatory CC-chemokines. Despite its prominent biological role, little is known about the structure/function relationship within ACKR2, which regulates ligand binding. Here we demonstrate that a conserved tyrosine motif at the N terminus of ACKR2 is essential for ligand binding, internalization, and scavenging. In addition we demonstrate that sulfation of this motif contributes to ligand internalization. Furthermore, a peptide derived from this region is capable of binding inflammatory chemokines and inhibits their interaction with their cognate signaling receptors. Importantly, the peptide is only active in the sulfated form, further confirming the importance of the sulfated tyrosines for function. Finally, we demonstrate that the bacterial protease, staphopain A, can cleave the N terminus of ACKR2 and suppress its ligand internalization activity. Overall, these results shed new light on the nature of the structural motifs in ACKR2 that are responsible for ligand binding. The study also highlights ACKR2-derived N-terminal peptides as being of potential therapeutic significance.
authors.affiliation: From the Chemokine Research Group, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G12 8TA, United Kingdom.
authors.forename: Kay D
authors.initials: KD
authors.lastname: Hewit
authors.forename: Alasdair
authors.initials: A
authors.lastname: Fraser
authors.forename: Robert J B
authors.initials: RJ
authors.lastname: Nibbs
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Graham
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D016466:CHO Cells; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004705:Endocytosis / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding; D034622:RNA Interference; D019707:Receptors, Chemokine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013431:Sulfates / Q000378:metabolism; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*; D000097628:Chemokine Receptor D6
chemical_list: D018925:Chemokines; D003546:Cysteine Endopeptidases; D008024:Ligands; D010455:Peptides; D019707:Receptors, Chemokine; D013431:Sulfates; D014443:Tyrosine; C515708:ACKR2 protein, human; D000097628:Chemokine Receptor D6; C501295:staphopain A protein, Staphylococcus aureus
keywords: 7-Helix Receptor; Chemokines; Flow Cytometry; Inflammation; Mutagenesis