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.
Golding
Hana
H
Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA. goldingh@cber.FDA.gov
Khurana
Surender
S
Yarovinsky
Felix
F
King
Lisa R
LR
Abdoulaeva
Galina
G
Antonsson
Liselotte
L
Owman
Christer
C
Platt
Emily J
EJ
Kabat
David
D
Andersen
John F
JF
Sher
Alan
A
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