CCR5 N-terminal region plays a critical role in HIV-1 inhibition by Toxoplasma gondii-derived cyclophilin-18.
Molecular mimicry of chemokine ligands has been described for several pathogens. Toxoplasma gondii produces a protein, cyclophilin-18 (C-18), which binds to the human immunodeficiency virus (HIV) co-receptor CCR5 and inhibits fusion and infection of T cells and macrophages by R5 viruses but not by X4 viruses. We recently identified structural determinants of C-18 required for anti-HIV activity (Yarovinsky, F., Andersen, J. F., King, L. R., Caspar, P., Aliberti, J., Golding, H., and Sher, A. (2004) J. Biol. Chem. 279, 53635-53642). Here we have elucidated the fine specificity of CCR5 residues involved in binding and HIV inhibitory potential of C-18. To delineate the regions of CCR5 involved in C-18 binding, we analyzed C-18 inhibition of cells expressing CXCR4/CCR5 chimeric receptors and CCR5 with a truncated N terminus (Delta2-19). These experiments identified a critical role for the N terminus of CCR5 in C-18 binding and anti-HIV activity. Studies with a large panel of CCR5 N-terminal peptides, including Tyr-sulfated analogues, truncated peptides, and alanine-scanning mutants, suggested that each of the 12-17 amino acids in the N terminus of CCR5 are essential for C-18 binding and inhibitory activity. Tyr sulfation did not improve C-18 reactivity. This finding is of interest because the same CCR5 N-terminal region was shown previously to play a key role in binding of HIV-1 envelope glycoproteins. The elucidation of the functional C-18-binding mechanism may help in the rational design of novel antiviral agents against HIV.
Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA. goldingh@cber.FDA.gov
Hana
H
Golding
Surender
S
Khurana
Felix
F
Yarovinsky
Lisa R
LR
King
Galina
G
Abdoulaeva
Liselotte
L
Antonsson
Christer
C
Owman
Emily J
EJ
Platt
David
D
Kabat
John F
JF
Andersen
Alan
A
Sher
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D021983:Cyclophilins / Q000378:metabolism / Q000494:pharmacology*; D023581:HIV Fusion Inhibitors / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000494:pharmacology*; D019713:Receptors, CCR5 / Q000737:chemistry / Q000502:physiology*; D014122:Toxoplasma / Q000737:chemistry*
D023581:HIV Fusion Inhibitors; D015800:Protozoan Proteins; D019713:Receptors, CCR5; D021983:Cyclophilins