The prefoldin-like protein AtURI exhibits characteristics of intrinsically disordered proteins.

The prefoldin-like protein UNCONVENTIONAL PREFOLDIN RPB5 INTERACTOR (URI) participates in diverse cellular functions, including protein homeostasis, transcription, translation, and signal transduction. Thus, URI is a highly versatile protein, although the molecular basis of this versatility remains unknown. In this work, we show that Arabidopsis thaliana (Arabidopsis) URI (AtURI) possesses a large intrinsically disordered region (IDR) spanning most of the C-terminal part of the protein, a feature conserved in yeast and human orthologs. Our findings reveal two key characteristics of disordered proteins in AtURI: promiscuity in interacting with partners and protein instability. We propose that these two features contribute to providing AtURI with functional versatility.

Biophysical evaluation of cardiolipin content as a regulator of the membrane lytic effect of antimicrobial peptides.

Cardiolipin is an anionic tetra-acyl chained glycerophospholipid that increases lipid packing levels and induces intrinsic negative curvature in membranes. Cardiolipin is found in Staphylococcus aureus (S. aureus) membranes, where increased levels of this lipid are induced at the expense of diacyl phosphatidylglycerol in response to stress. We investigate cardiolipin as an inhibitor of the lytic activity of the cationic antimicrobial peptides LL-37 and ∆M2 in model systems with varying phosphatidylglycerol/cardiolipin ratios. Using HPTLC, we show that S. aureus (RN4220), under different growth conditions, has a phosphatidylglycerol/cardiolipin ratio of 80:20. From this, we chose three model systems to evaluate (100:0, 80:20, 60:40). ∆M2 presents higher binding affinity towards all mixtures compared to LL-37. This correlates with the higher antimicrobial activity of ∆M2 compared to LL-37 in S. aureus (MIC90 of 14 µM for ∆M2 and 57.7 µM for LL-37). Laurdan GP shows that Cardiolipin decreases lipid headgroup spacing. We find that cardiolipin does not affect ∆M2 or LL-37 binding to phosphatidylglycerol/cardiolipin liposomes. Instead, cardiolipin inhibits the ability of both peptides to induce calcein leakage in model liposomes. In conclusion, cardiolipin can reduce cAMP activity by inhibiting lysis but not binding.

Identification and evaluation of Galleria mellonella peptides with antileishmanial activity.

Leishmaniasis is a neglected disease, World Health Organization (WHO) declared it as high priority worldwide. Colombia is one of the 98 countries in which the disease caused more than 17.000 cases per year. There is a need to explore novel therapies to reduce the side effects of the current treatments. For this reason, this study was aimed to evaluate Galleria mellonella hemolymph for potential peptides with anti-parasitic activity. Larvae were challenged with Leishmania (V) panamensis promastigotes and hemolymph was analyzed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), reversed-phase chromatography (RP-HPLC), two-dimensional gel electrophoresis and liquid chromatography-mass spectroscopy (LC/MS). The immunological response of Galleria mellonella was followed by SDS-PAGE, immunized hemolymph was fractionated by RP-HPLC where fractions 5 and 11 showed the highest antileishmanial activity. From these fractions 15 spots were isolated by 2D gel electrophoresis and evaluated by LC/MS to identify the peptides present in the spots. After the analysis Moricin-B, Moricin-C4, Cecropin-D and Anionic Peptide 2 were identified due to the immune challenge with Leishmania promastigotes. Anionic peptide 2 and Cecropin-D were synthesized and evaluated for antileishmanial activity. The results showed that Anionic peptide 2 presented more anti-parasitic activity. This study showed for the first time the anti-parasitic potential of peptides derived from hemolymph of Galleria mellonella.