TY - JOUR

T1 - Identification of a Salt Bridge That Is Functionally Important for Chemokine Receptor CXCR1 but not CXCR2

AU - Våbenø, Jon

AU - Oliva-Santiago, Marta

AU - Jørgensen, Astrid S.

AU - Karlshøj, Stefanie

AU - Rosenkilde, Mette M.

N1 - Funding Information: Maibritt Sigvardt Baggesen and Søren Petersen are thanked for their excellent technical assistance. Financial support was obtained from The NovoNordisk Foundation (NF20OC0062899), The Carlsberg Foundation (CF14-0707), Kirsten and Freddy Johansens (KFJ) Foundation (2017-112697), and as a donation from the deceased Valter Alex Torbjørn (VAT) Eichmuller (2020-117043). Publisher Copyright: © 2023 The Authors. Published by American Chemical Society.

PY - 2023

Y1 - 2023

N2 - CXC chemokine receptors 1 (CXCR1) and 2 (CXCR2) have high sequence similarity and overlapping chemokine ligand profiles. Residue positions 3.32 and 7.39 are critical for signal transduction in the related CXCR4, and in these positions CXCR1 and CXCR2 contain oppositely charged residues (Lys3.32 and Glu7.39). Experimental and computed receptor structures reveal the possible formation of a salt bridge between transmembrane (TM) helices 3 and 7 via these two residues. To investigate the functional importance of Lys1173.32 and Glu2917.39 in CXCR1, along with the flanking Glu1183.33, we performed a signaling study on 16 CXCR1 mutants using two different CXCL8 isoforms. While single Ala-mutation (K1173.32A, E2917.39A) and charge reversal (K1173.32E, E2917.39K) resulted in nonfunctional receptors, double (K1173.32E-E2917.39K) and triple (K1173.32E-E1183.33A-E2917.39K) mutants rescued CXCR1 function. In contrast, the corresponding mutations did not affect the CXCR2 function to the same extent. Our findings show that the Lys3.32-Glu7.39 salt bridge between TM3 and −7 is functionally important for CXCR1 but not for CXCR2, meaning that signal transduction for these highly homologous receptors is not conserved.

AB - CXC chemokine receptors 1 (CXCR1) and 2 (CXCR2) have high sequence similarity and overlapping chemokine ligand profiles. Residue positions 3.32 and 7.39 are critical for signal transduction in the related CXCR4, and in these positions CXCR1 and CXCR2 contain oppositely charged residues (Lys3.32 and Glu7.39). Experimental and computed receptor structures reveal the possible formation of a salt bridge between transmembrane (TM) helices 3 and 7 via these two residues. To investigate the functional importance of Lys1173.32 and Glu2917.39 in CXCR1, along with the flanking Glu1183.33, we performed a signaling study on 16 CXCR1 mutants using two different CXCL8 isoforms. While single Ala-mutation (K1173.32A, E2917.39A) and charge reversal (K1173.32E, E2917.39K) resulted in nonfunctional receptors, double (K1173.32E-E2917.39K) and triple (K1173.32E-E1183.33A-E2917.39K) mutants rescued CXCR1 function. In contrast, the corresponding mutations did not affect the CXCR2 function to the same extent. Our findings show that the Lys3.32-Glu7.39 salt bridge between TM3 and −7 is functionally important for CXCR1 but not for CXCR2, meaning that signal transduction for these highly homologous receptors is not conserved.

KW - chemokine receptor

KW - chemokine recognition site

KW - CKR signaling

KW - CXCR1

KW - CXCR2

KW - GPCR

KW - inositol triphosphate

KW - salt bridge

U2 - 10.1021/acsptsci.3c00070

DO - 10.1021/acsptsci.3c00070

M3 - Journal article

C2 - 37588755

AN - SCOPUS:85166751298

VL - 6

SP - 1120

EP - 1128

JO - ACS Pharmacology and Translational Science

JF - ACS Pharmacology and Translational Science

SN - 2575-9108

IS - 8

ER -