Structure-function study and anti-HIV activity of synthetic peptide analogues derived from viral chemokine vMIP-II

The viral macrophage inflammatory protein II (vMIP-II) shows a broad spectr um interaction with both CC and CXC chemokine receptors including CCR5 and CXCR4, two principal coreceptors for the cellular entry of human immunodefi ciency virus type 1 (HIV-1). Recently, we have shown that a synthetic pepti de derived from the N-terminus of vMIP-II, designated as V1, is a potent an tagonist of CXCR4 but not CCRS [Zhou, N., et al. (2000) Biochemistry 39, 37 82-3787]. In this study, we synthesized a series of new peptides derived fr om other regions of vMIP-II and characterized their binding activities with both CXCR4 and CCRS. The results provided further support for the notion t hat the N-terminus of vMIP-II is the major determinant for CXCR4 recognitio n and that VMIP-II probably interacts with other chemokine receptors such a s CCRS with different sequence and conformational determinants. To understa nd the structure-function relationship of V1 peptide, its solution conforma tion was studied using circular dichroism spectroscopy, which showed a rand om conformation similar to that of the corresponding N-terminus in native V MIP-II. In addition, we synthesized a series of mutant analogues of VI cont aining alanine, glycine, or phenylalanine substitution at various positions . Residues Val-1, Arg-7, and Lys-9 of VI peptide were found to be critical for receptor interaction, because single alanine replacement at these posit ions dramatically decreased peptide binding to CXCR4. In contrast, alanine or phenylalanine substitution at Cys-ll led to significant enhancement in p eptide affinity for CXCR4. Finally, we showed that V1 peptide inhibits HIV- 1 replication in CXCR4(+) T-cell lines, These studies provide new insights into the structure-function relationship of V1 peptide and demonstrate that this peptide may be a lead for the development of therapeutic agents.