title: Semisynthetic analogues of PSC-RANTES, a potent anti-HIV protein.
abstract: New HIV prevention methods are needed, and among those currently being explored are "microbicides", substances applied topically to prevent HIV acquisition during sexual intercourse. The chemokine analogue PSC-RANTES (N(alpha)(n-nonanoyl)-des-Ser(1)-[ L-thioprolyl(2), L-cyclohexylglycyl(3)]-RANTES(4-68)) is a highly potent HIV entry inhibitor which has shown promising efficacy in its initial evaluation as a candidate microbicide. However, a way must be found to produce the molecule by cheaper means than total chemical synthesis. Since the only noncoded structures are located at the N-terminus, a possible solution would be to produce a protein fragment representing all but the N-terminal region using low-cost recombinant production methods and then to attach, site specifically, a short synthetic fragment containing the noncoded N-terminal structures. Here, we describe the evaluation of a range of different conjugation chemistries in order to identify those with potential for development as economical routes to production of a PSC-RANTES analogue with antiviral activity as close as possible to that of the parent protein. The strategies tested involved linkage through oxime, hydrazone/hydrazide, and Psi[CH2-NH] bonds, as well as through a peptide bond obtained either by a thiazolidine rearrangement or by direct alpha-amino acylation of a protein fragment in which 4 of the 5 lysine residues of the native sequence were replaced by arginine (the fifth lysine is essential for activity). Where conjugation involved replacement of one or more residues with a linker moiety, the point in the main chain at which the linker was introduced was varied. The resulting panel of 22 PSC-RANTES analogues was evaluated for anti-HIV activity in an entry inhibition assay. The [Arg (25,45,56,57)] PSC-RANTES analogue has comparable potency to PSC-RANTES, and one of the oxime linked analogues, 4L-57, has potency only 5-fold lower, with scope for improvement. Both represent promising leads for development as microbicide compounds that could be produced at low cost via semisynthesis.
authors.affiliation: Department of Structural Biology and Bioinformatics, Centre Médical Universitaire, 1 rue Michel Servet, 1211 Geneva 4, Switzerland.
authors.forename: Hubert
authors.initials: H
authors.lastname: Gaertner
authors.forename: Robin
authors.initials: R
authors.lastname: Offord
authors.forename: Paolo
authors.initials: P
authors.lastname: Botti
authors.forename: Gabriel
authors.initials: G
authors.lastname: Kuenzi
authors.forename: Oliver
authors.initials: O
authors.lastname: Hartley
mesh_terms: D018946:Chemokine CCL5 / Q000737:chemistry / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D023581:HIV Fusion Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D018946:Chemokine CCL5; D023581:HIV Fusion Inhibitors; C492865:RANTES, N(alpha)-(n-nonanoyl)-desSer(1)-(thioproline(2),cyclohexylglycine(3))-