Structural variety of membrane permeable peptides

Peptide-mediated protein delivery into living cells has been attracting our attention. Among the peptides that have been reported to have carrier activity, the one from the human immunodeficient virus (HIV)-1 Tat has been most often used for the introduction of exogenous macromolecules into cells. We have shown that not only the Tat peptide, but also various arginine-rich peptides showed very similar characteristics in translocation, and the possible presence of ubiquitous internalization mechanisms among the arginine-rich peptides has also been suggested. These arginine-rich peptides includes ones derived from HIV-1 Rev and flock house virus coat proteins. The linear- and branched-chain peptides containing approximately 8 residues of arginine also show a similar ability. In this review, we present the structural variety of membrane permeable peptides and provide a survey of the findings on the translocation of these peptides through the cell membranes.

Construction of HIV Rev peptides containing peptide nucleic acid that bind HIV RRE IIB RNA

Peptides containing peptide nucleic acid (PNA) have been designed and synthesized to construct molecules recognizing a bulge or a loop structure of RNA. Such peptides were here designed from the HIV Rev protein that can bind the stem-loop IIB of the Rev responsive element (RRE) RNA. Variations of PNA modulated the binding affinities of the peptides to RRE IIB RNA.

Helper and cytotoxic T cell responses of HIV type 1-infected individuals to synthetic peptides of HIV type 1 Rev

In cell-mediated immunity T cells recognize peptide fragments of the antigenic protein in association with major histocompatibility complex (MHC) proteins. Synthetic 9- to 16-mer peptides have been widely used to identify the region(s) of a protein that act as T cell epitope. Here, we report antigenic peptides identified on HIV-1 regulatory protein Rev. Four synthetic peptides (amino acids 9-23, 25-39, 33-48, and 41-56) were first shown to stimulate T helper (Th) cell proliferation in peripheral blood lymphocytes (PBLs) derived from HIV-seropositive (HIV+) individuals. The same peptides induced cytotoxic T lymphocyte (CTL) activities toward the autologous target cells incubated with the peptides. Both responses were specific to the HIV infection as HIV-seronegative (HIV-) control individuals showed no significant proliferative or cytotoxic activity. The proliferating cells were CD4+ T cells, and CTL activity was mediated by CD8+ human leukocyte antigen (HLA)-restricted T cells. The identification of peptides containing epitopes that can induce both Th and CTL responses to regulatory proteins of HIV-1 in infected individuals might be important for vaccine development against AIDS. Since early regulatory proteins of HIV are expressed by the infected cells before the initiation of the synthesis of structural proteins, a CTL response against these proteins could destroy the infected cells before the release of infectious virions.

Specific regulation of mRNA splicing in vitro by a peptide from HIV-1 Rev

The Rev protein of HIV-1 regulates the synthesis of partially spliced forms of cytoplasmic viral mRNA by binding to a cis-acting RNA sequence, the Rev response element (RRE). We have investigated the regulation of splicing in vitro and have shown that Rev specifically inhibits splicing of pre-mRNAs containing an RRE by 3- to 4-fold. A synthetic peptide of 17 amino acids containing the RNA-binding domain of Rev is highly functional and specifically inhibits splicing by up to 30-fold. Other peptides that bind to the RRE with high affinity, but with low specificity, do not specifically inhibit splicing. Six repeated monomeric binding sites for the peptide can substitute for the RRE, indicating that regulation by Rev requires interactions with multiple sites. The peptide acts at a step in the assembly of splicing complexes, suggesting that one of the functions of the basic region of Rev is to prevent formation of a functional spliceosome.