Molecular engineering of RANTES peptide mimetics with potent anti‐HIV‐1 activity

The chemokine receptor CCR5 is utilized as a critical coreceptor by most primary HIV‐1 strains. While the lack of structural information on CCR5 has hampered the rational design of specific inhibitors, mimetics of the chemokines that naturally bind CCR5 can be molecularly engineered. We used a structure‐guided approach to design peptide mimetics of the N‐loop and βl‐strand regions of regulated on activation normal T‐cell‐expressed and secreted (RANTES)/CCL5, which contain the primary molecular determinants of HIV‐1 blockade. Rational modifications were sequentially introduced into the N‐loop/βl‐strand sequence, leading to the generation of mimetics with potent activity against a broad spectrum of CCR5‐specific HIV‐1 isolates (IC 50 range: 104–640 nM) but lacking activity against CXCR4‐specific HIV‐1 isolates. Functional enhancement was initially achieved with the stabilization of the N loop in the β‐extended conformation adopted in full‐length RANTES, as confirmed by nuclear magnetic resonance (NMR) analysis. However, the most dramatic increase in antiviral potency resulted from the engraftment of an in siZico‐optimized linker segment designed using de novo structure‐prediction algorithms to stabilize the C‐terminal α‐helix and experimentally validated by NMR. Our mimetics exerted CCR5‐antagonistic effects, demonstrating that the antiviral and proinflammatory functions of RANTES can be uncoupled. RANTES peptide mimetics provide new leads for the development of safe and effective HIV‐1 entry inhibitors.—Lusso, P., Vangelista, L., Cimbro, R., Secchi, M., Sironi, F., Longhi, R., Faiella, M., Maglio, O., Pavone, V. Molecular engineering of RANTES peptide mimetics with potent anti‐HIV‐1 activity. FASEB J. 25, 1230–1243 (2011). www.fasebj.org