[en] Background
The atypical chemokine receptor ACKR3, formerly CXCR7, binds the endogenous chemokines CXCL12 and CXCL11, as well as the virus-encoded chemokine vCCL2. ACKR3 is crucially involved in various physiological processes but also in viral infection and cancer development, making it a promising drug target, yet a potent antagonist for this receptor is still lacking. Acting as a scavenging receptor, ACKR3 internalizes chemokines without activating the canonical G-protein signaling. ACKR3 extracellular domains present three disulfide bridges, two being conserved among chemokine receptors and one being exclusive to ACKR3, forming a four-residue loop of so far unknown function in the receptors’ N terminus.
Goal
Investigate the impact of extracellular disulfide bridges on surface expression, ligand binding and activation of ACKR3 in comparison to CXCR4, the second receptor for CXCL12
Approach
Creation of C to S mutants, breaking all three disulfide bridges present in ACKR3
1) Connecting the N terminus with ECL3 (present in all chemokine receptors) (C34S-C287S)
2) Bridging ECL1 and ECL2, (present in all G protein-coupled receptors) (C117S-C196S)
3) Forming a four-residue loop in the N terminus (unique for ACKR3) (C21S –C26S)
And creation of a 4th mutant: four internal residues of the N-terminal loop to glycine (C21-G4-C26)
