Hemagglutinating activity and conformation of a lactose-binding lectin from mushroom Agrocybe cylindracea

Vicia ervilia lectin (VEA) has an antibiofilm effect on both Gram-positive and Gram-negative pathogenic bacteria

Bacterial growing resistance to antibiotics poses a critical threat to global health. This study investigates, for the first time, the antibiofilm properties of Vicia ervilia agglutinin (VEA) from six different V. ervilia accessions against pathogenic bacteria, and the yeast Candida albicans. In the absence of antimicrobial properties, purified VEA significantly inhibited biofilm formation, both in Gram-positive and Gram-negative bacteria, but not in C. albicans. With an inhibitory concentration ranging from 100 to 500 µg/ml, the VEA antibiofilm activity was more relevant against the Gram-positive bacteria Streptococcus aureus and Staphylococcus epidermidis, whose biofilm was reduced up to 50% by VEA purified from accessions #5 and #36. VEA antibiofilm variability between accessions was observed, likely due to co-purified small molecules rather than differences in VEA protein sequences. In conclusion, VEA seed extracts from the accessions with the highest antibiofilm activity could represent a valid approach for the development of an effective antibiofilm agent.

Purification and Biochemical Characterization of Novel Galectin from the Black Poplar Medicinal Mushroom Cyclocybe cylindracea (Agaricomycetes) Strain MEST42 from Algeria

In the present study, a new galectin designated Cyclocybe cylindracea lectin (CCL) was extracted from the fruiting bodies of the wild black popular mushroom C. cylindracea grown in Algeria. The protein was isolated using sepharose 4B as affinity chromatography matrix, and galactose as elutant. The purified galectin was composed of two subunits of 17.873 kDa each, with a total molecular mass of 35.6 kDa. Its agglutinant activity was impeded by galactose and its derivatives, as well as melibiose. Lactose showed the highest affinity, with a minimal inhibitory concentration of 0.0781 mM. CCL was sensitive to extreme pH conditions, and its binding function decreased when incubated with 10 mM EDTA, and it could be restored by metallic cations such as Ca2+, Mg2+, and Zn2+. CCL agglutinated human red blood cells, without any discernible specificity. Circular dichroism spectra demonstrated that its secondary structure contained β-sheet as dominant fold. In addition, bioinformatics investigation on their peptide fingerprint obtained after MALDI-TOF/TOF ionization using mascot software confirmed that CCL was not like any previous purified lectin from mushroom: instead, it possessed an amino acid composition with high similarity to that of the putative urea carboxylase of Emericella nidulans (strain FGSC A4/ATCC 38163/CBS 112.46/NRRL 194/M139) with 44% of similarity score.

A comprehensive review of secondary metabolites from the genus Agrocybe: Biological activities and pharmacological implications

The genus Agrocybe, situated within the Strophariaceae family, class Agaricomycetes, and phylum Basidiomycota, encompasses a myriad of species exhibiting significant biological activities. This review presents an integrative overview of the secondary metabolites derived from Agrocybe species, elucidating their respective biological activities and potential pharmacological applications. The metabolites under scrutiny encompass a diverse array of biological macromolecules, specifically polysaccharides and lectins, as well as a diverse group of 80 documented small molecular chemical constituents, classified into sterols, sesquiterpenes, volatile compounds, polyenes, and other compounds, their manifesting anti-inflammatory, anticancer, antioxidant, hepatoprotective, antimicrobial, and antidiabetic activities, these metabolites, in which polysaccharides exhibit abundant activities, underscore the potential of the Agrocybe genus as a valuable source of biologically active natural products. The present review emphasises the need for escalated research into Agrocybe, including investigations into the biosynthetic pathways of these metabolites, which could foster the development of novel pharmaceutical therapies to address various health challenges.

Prokaryotic expression, purification, physicochemical properties and antifungal activity analysis of phloem protein PP2-A1 from cucumber

Phloem protein 2 (PP2) is a protein having lectin properties that can be isolated from the phloem sap. Based on our previous proteomic study of phloem sap of Cucumis sativus, it was found that the expression of PP2 A1-like was significantly up-regulated under salt stress, which may be a molecular mechanism of plant adaptation to stress. This paper carried out the expression and purification of the CsPP2-A1 gene in E. coli for further characteristic analysis. The results demonstrated that the CsPP2-A1 in shake flask cultures was mainly expressed in the soluble form at 15 °C or in inclusion bodies at 37 °C. Secondly, Ni-IDA affinity chromatography and SDS-PAGE were employed to yield highly purified CsPP2-A1 protein. The purified CsPP2-A1 was then subjected to Western blot and MALDI-TOF-MS analysis for protein identification. The biological activity analysis results showed that CsPP2-A1 had hemagglutinating activities to rabbit erythrocytes, and Chitotetraose may be the specific inhibitory sugar of CsPP2-A1. The optimal hemagglutination activity of CsPP2-A1 protein was achieved between pH 5-9, and between 20 and 60 °C. Moreover, CsPP2-A1 had significant inhibitory effects on Botrytis cinerea and Phytophthora infestans, and the inhibitory effect on B. cinerea was better than that on P. infestans.

Conformational study reveals amino acid residues essential for hemagglutinating and anti-proliferative activities of Clematis montana lectin

Clematis montana lectin (CML), a novel mannose-binding lectin purified from C. montana Buch.-Ham stem (Ranunculaceae), has been proved to have hemagglutinating activity in rabbit erythrocytes and apoptosis-inducing activity in tumor cells. However, the biochemical properties of CML have not revealed and its structural information still needs to be elucidated. In this study, it was found that CML possessed quite good thermostability and alkaline resistance, and its hemagglutinating activity was bivalent metal cation dependent. In addition, hemagglutination test and fluorescence spectroscopy proved that GuHCl, urea, and sodium dodecyl sulfate could change the conformation of CML and further caused the loss of hemagglutination activity. Moreover, the changes of fluorescence spectrum indicated that the tryptophan (Trp) microenvironment conversion might be related to the conformation and bioactivities of CML. In addition, it was also found that Trp residues, arginine (Arg) residues, and sulfhydryl were important for the hemagglutinating activity of CML, but only Trp was proved to be crucial for the CML conformation. Furthermore, the Trp, Arg, and sulfhydryl-modified CML exhibited 97.17%, 76.99%, and 49.64% loss of its anti-proliferative activity, respectively, which was consistent with the alterations of its hemagglutinating activity. Given these findings, Trp residues on the surface of CML are essential for the active center to form substrate-accessible conformation and suitable environment for carbohydrate binding.

Comprehensive list of lectins: origins, natures, and carbohydrate specificities

More than 100 years have passed since the first lectin ricin was discovered. Since then, a wide variety of lectins (lect means "select" in Latin) have been isolated from plants, animals, fungi, bacteria, as well as viruses, and their structures and properties have been characterized. At present, as many as 48 protein scaffolds have been identified as functional lectins from the viewpoint of three-dimensional structures as described in this chapter. In this chapter, representative 53 lectins are selected, and their major properties that include hemagglutinating activity, mitogen activity, blood group specificity, molecular weight, metal requirement, and sugar specificities are summarized as a comprehensive table. The list will provide a practically useful, comprehensive list for not only experienced lectin users but also many other non-expert researchers, who are not familiar to lectins and, therefore, have no access to advanced lectin biotechnologies described in other chapters.

Fungal lectins: a growing family

Fungi are members of a large group of eukaryotic organisms that include yeasts and molds, as well as the most familiar member, mushrooms. Fungal lectins with unique specificity and structures have been discovered. In general, fungal lectins are classified into specific families based on their amino acid sequences and three-dimensional structures. In this chapter, we provide an overview of the approximately 80 types of mushroom and fungal lectins that have been isolated and studied to date. In particular, we have focused on ten fungal lectins (Agaricus bisporus, Agrocybe cylindracea, Aleuria aurantia, Aspergillus oryzae, Clitocybe nebularis, Marasmius oreades, Psathyrella velutina, Rhizopus stolonifer, Pholiota squarrosa, Polyporus squamosus), many of which are commercially available and their properties, sugar-binding specificities, structural grouping into families, and applications for biological research being described. The sialic acid-specific lectins (Agrocybe cylindracea and Polyporus squamosus) and fucose-specific lectins (Aleuria aurantia, Aspergillus oryzae, Rhizopus stolonifer, and Pholiota squarrosa) each showed potential for use in identifying sialic acid glycoconjugates and fucose glycoconjugates. Although not much is currently known about fungal lectins compared to animal and plant lectins, the knowledge accumulated thus far shows great promise for several applications in the fields of taxonomy, biomedicine, and molecular and cellular biology.

Purification, characterization, and molecular cloning of a novel antifungal lectin from the roots of Ophioglossum pedunculosum

A novel mannan-specific lectin was isolated from the roots of a traditional Chinese herbal medicine, Ophioglossum pedunculosum through ion-exchange chromatography and gel filtration. With a molecular mass of 19,835.7 Da demonstrated by MALDI-TOF analysis, this novel agglutinin was designated as O. pedunculosum agglutinin (OPA), specifically agglutinating human O erythrocytes and rabbit erythrocytes. The hemagglutination could be strongly inhibited by mannan and thyroglobulin, the activity of which was stable in pH range of 4.0-8.0 and at temperatures below 50 °C. Chemical modification studies indicated that tryptophan and arginine residues were essential for its hemagglutinating activity. Meanwhile, it showed antifungal activities toward Sclerotium rolfsii and Fusarium graminearum. In addition, to amplify cDNA of OPA by 3'/5'-rapid amplification of cDNA ends (RACE), the N-terminal 30 amino acids sequence of OPA was determined, and degenerate primers were designed. The obtained full-length cDNA of OPA contained 885 bp with an open-reading frame of 600 bp encoding a precursor protein of 199 amino acids, while the mature protein had 170 amino acids.

A laccase with antiproliferative activity against tumor cells from an edible mushroom, white common Agrocybe cylindracea

A laccase, with HIV-1 reverse transcriptase inhibitory activity (IC(50)=12.7 μM) and antiproliferative activity against HepG2 cells (IC(50)=5.6 μM) and MCF7 cells (IC(50)=6.5 μM), was purified from fresh fruiting bodies of the edible white common Agrocybe cylindracea mushroom. The laccase, which had a novel N-terminal sequence, displayed a molecular mass of 58 kDa within the range reported for most other mushroom laccases. The purification protocol entailed ion exchange chromatography on DEAE-cellulose, SP-Sepharose, and Q-Sepharose and gel filtration on Superdex 75. The laccase was adsorbed on DEAE-cellulose and Q-Sepharose, but unadsorbed on SP-Sepharose. Its optimum pH was pH 3-4 and its optimum temperature was 50°C. The activity of the isolated laccase differed from one substrate to another. The ranking was ABTS>N,N-dimethyl-1,4-phenylenediamine>hydroquinone>catechol>2-methylcatechol>pyrogallol.

Mushroom lectins: current status and future perspectives

Lectins are nonimmune proteins or glycoproteins that bind specifically to cell surface carbohydrates, culminating in cell agglutination. These are known to play key roles in host defense system and also in metastasis. Many new sources have been explored for the occurrence of lectins during the last few years. Numerous novel lectins with unique specificities and exploitable properties have been discovered. Mushrooms have attracted a number of researchers in food and pharmaceuticals. Many species have long been used in traditional Chinese medicines or functional foods in Japan and other Asian countries. A number of bioactive constituents have been isolated from mushrooms including polysaccharides, polysaccharopeptides, polysaccharide-protein complexes, proteases, ribonucleases, ribosome inactivating proteins, antifungal proteins, immunomodulatory proteins, enzymes, lectins, etc. Mushroom lectins are endowed with mitogenic, antiproliferative, antitumor, antiviral, and immune stimulating potential. In this review, an attempt has been made to collate the information on mushroom lectins, their blood group and sugar specificities, with an emphasis on their biomedical potential and future perspectives.