The recombinant disintegrin, jarastatin, inhibits platelet adhesion and endothelial cell migration.

Integrins are transmembrane heterodimeric glycoproteins, present in most cell types that act as mechanoreceptors, connecting extracellular matrix proteins to the cytoskeleton of the cell, mediating several physiological and pathological processes. The disintegrins are peptides capable of modulating the activity of integrins, such as αIIbß3, responsible for the platelet aggregation and αvß3, related to angiogenesis. The aim of this study was to produce the recombinant disintegrin jarastatin (rJast), to evaluate its secondary structure and biological activity. rJast was expressed in the yeast Komagataella phaffii (earlier Pichia pastoris) purified using molecular exclusion chromatography and the internal sequence and molecular mass were confirmed by mass spectrometry. The yield was approximately 40 mg/L of culture. rJast inhibited platelet aggregation induced by 2-4 µM ADP, 10 nM thrombin, and 1 µg/mL collagen (IC50 of 244.8 nM, 166.3 nM and 223.5 nM, respectively). It also blocked the adhesion of platelets to collagen under continuous flow in approximately 60% when used 1 µM. We also evaluated the effect of rJast on HMEC-1 cells. rJast significantly inhibited the adhesion of these cells to vitronectin, as well as cell migration (IC50 1.77 µM) without changing the viability. Conclusions: rJast was successfully expressed with activity in human platelets aggregation identical to the native molecule. Also, rJast inhibits adhesion and migration of endothelial cells. Thus, being relevant for the development of anti-thrombotic and anti-angiogenic drugs.

Psd2 pea defensin shows a preference for mimetic membrane rafts enriched with glucosylceramide and ergosterol.

Psd2 is a pea defensin with 47 amino acid residues that inhibits the growth of fungal species by an uncharacterized mechanism. In this work, Psd2 interactions with model membranes mimicking the lipid compositions of different organisms were evaluated. Protein-lipid overlay assays indicated that Psd2 recognizes Fusarium solani glucosylceramide (GlcCerF.solani) and ergosterol (Erg) in addition to phosphatidylcholine (POPC) and some phosphatidylinositol species, such as PtdIns (3)P, (5)P and (3,5)P2, suggesting that these lipids may play important roles as Psd2 targets. Assays using lipid vesicles were also performed to study the behaviour and dynamics that occur after peptide-membrane interactions. Surface plasmon resonance analysis showed that Psd2 has a higher affinity for pure POPC and POPC-based vesicles containing GlcCer and Erg at a 70:30 proportion than for vesicles containing cholesterol (Chol). Partition experiments by fluorescence spectroscopy showed a decrease in Trp42 quantum yield of Psd2 in the presence of GlcCerF.solani and Erg, individually or in simultaneously enriched membranes. The partition coefficient (Kp) obtained indicated a Psd2 partition preference for this vesicles, confirmed by quenching assays using acrylamide and 5/16-doxyl-stearic acid. Furthermore, we showed that the presence of C8C9 double bonds and a methyl group at position C9 of the sphingoid base backbone of GlcCer was relevant to Psd2 activity against Aspergillus nidulans. These results are consistent with the selectivity of Psd2 against fungi and its lack of toxicity in human erythrocytes. Psd2 represents a promising natural compound for the treatment of fungal infections.