Two distinct CCR5 domains can mediate coreceptor usage by human immunodeficiency virus type 1.
The chemokine receptor CCR5 is the major fusion coreceptor for macrophage-tropic strains of human immunodeficiency virus type 1 (HIV-1). To define the structures of CCR5 that can support envelope (Env)-mediated membrane fusion, we analyzed the activity of homologs, chimeras, and mutants of human CCR5 in a sensitive gene reporter cell-cell fusion assay. Simian, but not murine, homologs of CCR5 were fully active as HIV-1 fusion coreceptors. Chimeras between CCR5 and divergent chemokine receptors demonstrated the existence of two distinct regions of CCR5 that could be utilized for Env-mediated fusion, the amino-terminal domain and the extracellular loops. Dual-tropic Env proteins were particularly sensitive to alterations in the CCR5 amino-terminal domain, suggesting that this domain may play a pivotal role in the evolution of coreceptor usage in vivo. We identified individual residues in both functional regions, Asp-11, Lys-197, and Asp-276, that contribute to coreceptor function. Deletion of a highly conserved cytoplasmic motif rendered CCR5 incapable of signaling but did not abrogate its ability to function as a coreceptor, implying the independence of fusion and G-protein-mediated chemokine receptor signaling. Finally, we developed a novel monoclonal antibody to CCR5 to assist in future studies of CCR5 expression.
Doranz
B J
BJ
Department of Pathology, University of Pennsylvania, Philadelphia 19104, USA.
Lu
Z H
ZH
Rucker
J
J
Zhang
T Y
TY
Sharron
M
M
Cen
Y H
YH
Wang
Z X
ZX
Guo
H H
HH
Du
J G
JG
Accavitti
M A
MA
Doms
R W
RW
Peiper
S C
SC
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA; D015686:Gene Products, env / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011323:Primates; D019713:Receptors, CCR5; D018121:Receptors, Cytokine / Q000378:metabolism*; D015728:Receptors, HIV / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015686:Gene Products, env; D019713:Receptors, CCR5; D018121:Receptors, Cytokine; D015728:Receptors, HIV; D004247:DNA