Peptidesidos

Peptidesidos are a recently identified group of short peptide molecules that have been isolated from certain Gram‑negative bacteria and some eukaryotic tissues. The name derives from the combination of “peptide” with the suffix “‑idos,” which is used in biochemical nomenclature to denote a specific structural motif characterized by a cyclic backbone and an appended hydrophobic tail. Unlike classical signaling peptides that typically act through G‑protein coupled receptors, peptidesidos have been shown to interact directly with membrane lipid bilayers, inducing localized curvature and facilitating endocytosis of certain protein cargoes.

Structural studies using NMR spectroscopy have revealed that peptidesidos generally consist of 8–12 amino acid residues with a conserved cysteine–proline motif that forms an intramolecular disulfide bridge. This bridge stabilizes a compact, amphipathic α‑helix that inserts into the outer leaflet of the plasma membrane. The C‑terminal tail is often acetylated, which contributes to membrane specificity and resistance to proteolytic degradation.

Functional assays in cell culture have demonstrated that peptidesidos can enhance the uptake of macromolecules such as plasmid DNA and therapeutic proteins, suggesting potential applications in drug delivery. In addition, some peptidesidos have exhibited antimicrobial activity at micromolar concentrations by disrupting bacterial membranes. Ongoing research is focused on elucidating the signal transduction pathways that are modulated by peptidesidos and on engineering synthetic analogues with improved efficacy and reduced cytotoxicity.