Effects of l- and d-REKR amino acid-containing peptides on HIV and SIV envelope glycoprotein precursor maturation and HIV and SIV replication

Abstract

The aim of the present study was to evaluate the capacity of synthetic l- and d-peptides encompassing the HIV-1BRU gp160 REKR cleavage site to interfere with HIV and simian immuno-deficiency virus (SIV) replication and maturation of the envelope glycoprotein (Env) precursors. To facilitate their penetration into cells, a decanoyl (dec) group was added at the N-terminus. The sequences synthesized included dec5d or dec5l (decREKRV), dec9d or dec9l (decRVVQREKRV) and dec14d or dec14l (TKAKRRVVQREKRV). The peptide dec14d was also prepared with a chloromethane (cmk) group as C-terminus. Because l-peptides exhibit significant cytotoxicity starting at 35μM, further characterization was conducted mostly with d-peptides, which exhibited no cytotoxicity at concentrations higher than 70μM. The data show that only dec14d and dec14dcmk could inhibit HIV-1BRU, HIV-2ROD and SIVmac251 replication and their syncytium-inducing capacities. Whereas peptides dec5d and dec9d were inactive, dec14dcmk was at least twice as active as peptide dec14d. At the molecular level, our data show a direct correlation between anti-viral activity and the ability of the peptides to interfere with maturation of the Env precursors. Furthermore, we show that when tested in vitro the dec14d peptide inhibited PC7 with an inhibition constant Ki = 4.6μM, whereas the peptide dec14l preferentially inhibited furin with a Ki = 28μM. The fact that PC7 and furin are the major prohormone convertases reported to be expressed in T4 lymphocytes, the principal cell targets of HIV, suggests that they are involved in the maturation of HIV and SIV Env precursors.

HIV envelope: challenges and opportunities for development of entry inhibitors

“…Interestingly, furin inhibitors are also of therapeutic interest for their role in cancer [52] . Examples of furin inhibitors of HIV envelope processing include peptides containing the HIV cleavage sequence (the amino acid sequence of REKR) 53 , 54 . Examples of protein inhibitors of furin include alpha-2 macroglobulin engineered to contain the furin cleavage site as bait [55] and alpha-1-antitrypsin, a potent inhibitor of serine proteases 56 , 57 .…”

Predicting proteolytic sites in extracellular proteins: only halfway there

“…This finding establishes the importance of furin-mediated processing for virus-infectivity. Accordingly, inhibitors of the host protease furin impede HIV-1 replication by interfering with the proteolytic processing of Env, suggesting they are useful for combating HIV-1 (Bahbouhi et al, 2002;Hallenberger et al, 1992;Kibler et al, 2004). Furthermore, inhibiting the production of peptides involved in various diseases by blocking the activity of the proteolytic enzymes is a promising approach (Basak, 2005;Bergeron et al, 2005;de Haan et al, 2004).…”

Polyarginine Inhibits gp160 Processing by Furin and Suppresses Productive Human Immunodeficiency Virus Type 1 Infection

“…This finding establishes the importance of furin-mediated processing for virus infectivity. Accordingly, there is emerging interest in identifying and developing anti-HIV-1 compounds that inhibit gp160 processing (5,6).…”