Although selected chemokines act as natural inhibitors of human immunodeficiency virus (HIV) infection, their inherent proinflammatory activity may limit a therapeutic use. To elucidate whether the antiviral and signaling functions of RANTES can be dissociated, several recombinant analogues mutated at the N terminus were generated and functionally compared with the wild‐type (WT) molecule, as well as with three previously described mutants. Substitution of selected residues within the N‐terminal region caused a marked loss of antiviral potency. By contrast, two unique analogues (C1.C5‐RANTES and L‐RANTES) exhibited an increased antiviral activity against different CXCR4‐negative HIV‐1 isolates grown in primary mononuclear cells or in macrophages. This enhanced HIV‐blocking activity was associated with an increased binding affinity for CCR5. Both C1.C5‐RANTES and L‐RANTES showed a dramatically reduced ability to trigger intracellular calcium mobilization via CCR3 or CCR5, while potently antagonizing the action of the WT chemokine. By contrast, two previously described analogues (RANTES3–68 and AOP‐RANTES) maintained a WT ability to trigger CCR5‐mediated signaling, while a third one (RANTES9–68) showed a dramatic loss of antiviral activity. These data demonstrate that the antiviral and signaling functions of RANTES can be uncoupled, opening new perspectives for the development of chemokine‐based therapeutic approaches for HIV infection.

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Inhibition of histone deacetylases (HDACs) leads to growth arrest, differentiation, or apoptosis of tumor cell lines, suggesting HDACs as promising targets for cancer therapy. At present, only one HDAC inhibitor (HDACi) is used in therapy: suberoylanilide hydroxamic acid (SAHA). Here, we describe the synthesis and biological evaluation of a new series of compounds derived from SAHA by substituting short alkyl chains at various positions of the phenyl ring. Such modifications induced variable effects ranging from partial loss of activity to increased potency. Through molecular modeling, we describe a possible interaction between HDAC7 proline 809, a residue that is strictly conserved within class 2 enzymes only, and the amide group of HDACi, while nuclear magnetic resonance experiments indicated that dimethyl m-substitution may stabilize the inhibitor in the active site. Our data provide novel information on the structure-activity relationship of HDACi and suggest new ways for developing second generation SAHA-like molecules.

Certain chemokines act as natural antagonists of human immunodeficiency virus (HIV) by blocking key viral coreceptors, such as CCR5 and CXCR4, on the surface of susceptible cells. Elucidating the structural determinants of the receptor-binding and HIV-inhibitory functions of these chemokines is essential for the rational design of derivative molecules of therapeutic value. Here, we identify the structural determinants of CCR5 recognition and antiviral activity of the CC chemokine RANTES, showing that critical residues form a solvent-exposed hydrophobic patch on the surface of the molecule. Moreover, we demonstrate that the biological function is critically dependent on dimerization, resulting in the exposure of a large ( approximately 180 A2), continuous hydrophobic surface. Relevant to the development of novel therapeutic approaches, we designed a retroinverted RANTES peptide mimetic that maintained both HIV- and chemotaxis-antagonistic functions.

In the framework of the EU programme for systematic sequencing of the Saccharomyces cerevisiae genome we determined the sequence of a 9359 bp fragment of the right arm of chromosome VII. Five open reading frames (ORFs) of at least 300 nucleotides were found in this region. YGR267c encodes a protein with significant similarity to the enzyme GTP‐cyclohydrolase I, that controls the first step in the biosynthetic pathway leading to various pterins and shows a high degree of sequence conservation from bacteria to mammals. We have recently demonstrated (Nardese et al., 1996) that YGR267c corresponds to the FOL2 gene, previously localized in the same chromosomal region by genetic mapping. The protein deduced from YGR270w belongs to the superfamily of putative ATPases associated with diverse cellular activities. It corresponds to the YTA7 gene, a member of a set of yeast genes coding for putative ATPases with high similarity to constituents of the 26S protease. The three ORFs YGR266w, YGR268c and YGR269w encode putative products of unknown function, with neither significant similarity to proteins in databases nor recognizable domains. YGR268c and YGR269w are partially overlapping ORFs: YGR268c seems to correspond to a real gene, whereas YGR269w is probably a fortuitous ORF. The sequence has been entered in the EMBL data library under Accession Number Y07893. © 1998 John Wiley & Sons, Ltd.