Littérature scientifique sur le sujet « Pleurotus ostreatus Lectin »

Crystals of Pleurotus ostreatus (oyster mushroom) lectin have been grown by the hanging-drop technique using ammonium sulfate as the precipitant at 293 K. Over a period of between two and three weeks, crystals of hexagonal bipyramidal morphology grew to maximum dimensions of 0.2 × 0.2 × 0.5 mm. The crystals belong to space group P6122 or P6522, with unit-cell parameters a = b = 155.9, c = 149.8 Å, V = 3153078 Å3, Z = 12 (assuming 50% solvent), and diffract to 4.1 Å at 293 K.

Abstract Pleurotus ostreatus Lectin (POL) is a 353 amino acid chain lectin that can be purified from the fruiting bodies of the very well-known and widely diffused edible oyster mushrooms (P. ostreatus). The lectin has been partially characterized by different groups and, although it was crystallized about 20 years ago, its 3D structure and the details of its interactions with carbohydrates are still unknown. This paper reports the 3D structure and ligand-binding properties of POL. We have determined the X-ray structure of the apo-protein purified from the fruiting bodies of the mushroom and that of the recombinant protein in complex with melibiose to a resolution of about 2 Å. The lectin is a homodimer in which the two polypeptide chains are linked by a disulfide bridge. A POL monomer is composed of two highly homologous β-jellyroll domains each of which containing a calcium-dependent carbohydrate-binding site. A high degree of sequence similarity is observed between the two carbohydrate-binding modules present in each monomer. The structure of the lectin in complex with melibiose reveals that a POL dimer has four calcium-dependent carbohydrate-binding sites. The interaction with sugars in solution has been characterized by isothermal titration calorimetry and saturation transfer difference NMR and it sheds new light on the molecular determinants of POL specificity. The lectin exhibits in vitro antiproliferative effects against human cancer cell lines and presents structural similarity with the prototype member of the CBM67 family, the noncatalytic domain of Streptomyces avermitilis α-rhamnosidase.

In this study, we examined aqueous extracts of the edible mushrooms Pleurotus ostreatus (oyster mushroom) and Lentinula edodes (shiitake mushroom). Proteome analysis was conducted using LC-Triple TOF-MS and showed the expression of 753 proteins by Pleurotus ostreatus, and 432 proteins by Lentinula edodes. Bioactive peptides: Rab GDP dissociation inhibitor, superoxide dismutase, thioredoxin reductase, serine proteinase and lectin, were identified in both mushrooms. The extracts also included promising bioactive compounds including phenolics, flavonoids, vitamins and amino acids. The extracts showed promising antiviral activities, with a selectivity index (SI) of 4.5 for Pleurotus ostreatus against adenovirus (Ad7), and a slight activity for Lentinula edodes against herpes simplex-II (HSV-2). The extracts were not cytotoxic to normal human peripheral blood mononuclear cells (PBMCs). On the contrary, they showed moderate cytotoxicity against various cancer cell lines. Additionally, antioxidant activity was assessed using DPPH radical scavenging, ABTS radical cation scavenging and ORAC assays. The two extracts showed potential antioxidant activities, with the maximum activity seen for Pleurotus ostreatus (IC50 µg/mL) = 39.46 ± 1.27 for DPPH; 11.22 ± 1.81 for ABTS; and 21.40 ± 2.20 for ORAC assays. This study encourages the use of these mushrooms in medicine in the light of their low cytotoxicity on normal PBMCs vis à vis their antiviral, antitumor and antioxidant capabilities.

Le lectine sono proteine ampiamente diffuse in natura che interagiscono in modo non covalente con i carboidrati. Tra le proteine dei funghi, le lectine sono le più ampiamente studiate perché possono mostrare attività antineoplastica su cellule tumorali umane. Partendo dai corpi fruttiferi del fungo edibile Pleurotus ostreatus è stata isolata una lectina composta da 373 aminoacidi che sembra essere in grado di inibire la crescita delle cellule neoplastiche umane. La lectina chiamata POL, Pleurotus ostreatus lectin, viene purificata mediante due passaggi cromatografici: uno che prevede l’utilizzo di una colonna con una matrice di Sefarosio 4B coniugata con mucina gastrica di maiale o con melibiosio seguita da una colonna a scambio ionico di carbossimetilcellulosa o mediante una gel filtrazione con Sephacryl S-100. Due modi alternativi di eluizione dalla colonna di affinità (con lattosio 0.2 M e con EDTA 5 mM) danno approssimativamente la stessa resa (2-5 mg) di proteina a partire da 500 g di funghi. I dati di diffrazione di raggi X dei cristalli sono stati raccolti in diverse linee della European Synchrotron Radiation Facility (ESRF) di Grenoble, in Francia. La struttura è stata inizialmente risolta per sostituzione isomorfa multipla (Multiple Isomorphous Replacement, MIR) e raffinata fino ad una risoluzione finale di 2.0 Å. L'unità asimmetrica contiene un monomero con due domini contenenti un totale di 22 catene β: 10 formano parte del dominio vicino all’ N terminale e 12 quello al C terminale. Le catene β sono radialmente disposte attorno ad un canale centrale. La lectina è caratterizzata da una debole attività β-glucosidasica (Vmax = 87.21 ± 1.5 nmol sec-1 mg-1, kcat = 0.044 s-1 e Km = 240 ± 0.26 mM) e dalla presenza di due atomi di calcio coordinati in due siti presenti in ciascun dominio. La POL è stata testata su cellule umane di cancro pancreatico (MiaPaCa-2) e sulle cellule HepG2, una linea cellulare immortale costituita da cellule di carcinoma epatico umano, e il suo effetto terapeutico è risultato evidente. La POL ricombinante, la cui espressione è stata ottimizzata in E.coli, nonostante cristallizzi in una serie di condizioni, produce cristalli che non diffrangono anche se l'attività enzimatica ed emoagglutinante è preservata. L’associazione della POL a nanoparticelle di acido poli (lattico-co-glicolico) potrebbe essere sfruttata sia per dirigere i nanocomposti di PLGA verso i tumori sia per l’utilizzo terapeutico della stessa POL incapsulata in nanoparticelle.
Lectins are proteins widely diffused in nature that interact non-covalently with carbohydrates. Of all the mushroom proteins, lectins are probably the most extensively investigated because it has been observed that they can exhibit antitumour activity on human cancer cells. A 373 amino acid lectin was isolated from the fruiting bodies of the edible oyster mushroom Pleurotus ostreatus was isolated since it appears to be able to inhibit the growth of human neoplastic cells. The lectin, named POL, Pleurotus ostreatus lectin, and it was purified using two chromatographic steps: a hog gastric mucin or melibiose column followed by a carboxymethyl-cellulose column or a Sephacryl S-100 gel filtration column. Two alternative ways of elution from the affinity column (with lactose 0.2M and with EDTA 5 mM) gave approximately the same yield (2-5 mg) of protein starting with 500 g of mushrooms. X-ray diffraction data of crystals were collected at various beamlines of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The structure was initially solved by Multiple Isomorphous Replacement (MIR) and it was then refined to a final highest resolution of 2.0 Å. The asymmetric unit contains one monomer with two domains and a total of 22 β-strands: 10 forming the domain closest to the N terminus and 12 nearest the C terminus. The two domains pack face to face and the β-sheet strands are radially arranged around a central tunnel packing face-to-face. The lectin is characterized by a weak β-glucosidase activity (Vmax=87.21±1.5 nmol sec-1 mg-1, kcat=0.044 s-1 and Km=240±0.26 μM) and by the presence of two Calcium atoms coordinated to two sites. POL was tested on human pancreatic cancer cells (MiaPaCa-2) and on HepG2 cells, a perpetual cell line consisting of human liver carcinoma cells, and its therapeutic effect was evident. Recombinant POL, whose expression was optimized in E.coli, crystallized in several conditions but the crystals did not diffract although the enzymatic and hemagglutinating activities were preserved. Encapsulation and/or binding to poly(lactic-co-glycolic acid) nanoparticles of POL might be exploited both to direct PLGA towards tumours and also to prepare POL-filled nanoparticles for therapeutic purposes.