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PubMed1983

On the mutagenicity of metabolites derived from the mushroom poison gyromitrin.

The hepatotoxic and carcinogenic hydrazine N-methyl-N-formyl hydrazine (MFH), which is formed from the mushroom poison gyromitrin by hydrolytic cleavage in vivo and in vitro during food processing is much more mutagenic for the strain TA 100 of Salmonella typhimurium in the presence of a metabolic activation system than in its absence. On the other hand, acetylated MFH (Ac-MFH) was not mutagenic for TA 100 in both test conditions. For the strain TA 98 neither MFH nor Ac-MFH were mutagenic both with and without metabolic activation. Therefore, a metabolic conversion of the free NH2-moiety of MFH into a genotoxic metabolite of MFH is postulated.

Acetaldehyde↗
PubMed1991

Characterization of bolesatine, a toxic protein from the mushroom Boletus satanas Lenz and it's effects on kidney cells.

Protein, DNA, and RNA syntheses were assayed in Madin Darby canine kidney cells (MDCK) treated by bolestaine, a toxic glycoprotein from the mushroom Boletus satanas (single chain, Mr 63,000 +/- 3000, pI 8.3 +/- 0.1, disulphide intrachain bridge) previously shown to be an inhibitor of in vitro protein synthesis. Cellular protein and DNA syntheses are inhibited in a dose-dependent manner after 24 h of incubation, whereas the uptake of the labelled precursors of proteins, DNA and RNA biosyntheses into the cells is not affected. The IC50 of bolesatine for protein synthesis is 0.14 microM in the cell culture medium. RNA synthesis is not inhibited at this concentration. The IC50 for DNA synthesis is 0.32 microM. When galactose is added to the culture medium, it decreases or even abolishes the toxic effects, indicating that it prevents the toxin from binding on the membrane and penetrating inside the cells. The profiles of polysomes in MDCK cells treated with bolesatine, compared to the untreated ones, show an increasing pool of polysomes indicating that the toxin acts on the peptidyl elongation step in the protein synthesis.

Animals↗
PubMed1979

A cytolytic protein from the edible mushroom, Pleurotus ostreatus.

Aqueous extracts of the edible mushroom, Pleurotus ostreatus, contain a substance that is lytic in vitro for mammalian erythrocytes. The hemolytic agent, pleurotolysin, was purified to homogeneity and found to be a protein lacking seven of the amino acids commonly found in proteins. In the presence of sodium dodecyl sulfate it exists a monomers of molecular weight 12 050 whereas under non-dissociating conditions it appears to exist as dimers. It is isoelectric at about pH 6.4. The sensitivity of erythrocytes from different animals correlates with sphingomyelin content of the erythrocyte membranes. Sheep erythrocyte membranes inhibit pleurotolysin-induced hemolysis and the inhibition is time and temperature dependent. Ability of membranes to inhibit hemolysis is abolished by prior treatment of membranes with specific phospholipases. Pleurotolysin-induced hemolysis is inhibited by liposomes prepared from cholesterol, dicetyl phosphate and sphingomyelin derived from sheep erythrocytes whereas a variety of other lipid preparations fail to inhibit. It is concluded that sphingomyelin plays a key role in the hemolytic reaction.

Agaricales↗
PubMed1992

Incorporation and binding of estrogens into melanin: comparison of mushroom and mammalian tyrosinases.

The activities of mushroom and melanoma tyrosinases towards the estrogens were compared. While the fungal enzyme is capable of hydroxylating estradiol to the 2-hydroxy compound and to oxidize the latter to the quinone, the mammalian enzyme does not have this ability. With dopa as substrate and an estrogen present in the reaction mixture, both enzyme reactions yield melanin with the steroid firmly incorporated into the pigment, although with the mammalian enzyme the incorporation is small. The steroid appears to be incorporated by covalent linkage. It is suggested that the incorporation of estrogens into melanin produced by mammalian tyrosinase is via their oxidation by oxidized intermediates of the dopa to melanin transformation. Melanin itself may function as oxidant for the estrogens. Whole melanoma cells are capable of binding estrogens and incorporating small amounts into melanosomes. Similarly, fresh melanosomes in isolation can incorporate estrogens into their structure, presumably by covalent bonding to their melanin.

Animals↗
PubMed1996

Purification and characterization of a lectin from the toxic mushroom Amanita pantherina.

A lectin (APL) was isolated from the mushroom Amantia pantherina by means of hydrophobic chromatography on Butyl-Toyopearl, affinity chromatography on bovine submaxillary mucin (BSM)-Toyopearl and gel filtration on Superose 12 HR10/30 using a FPLC system. This lectin is composed of two identical subunits of 22 kDa and the molecular mass of the intact lectin was estimated to be 43 kDa by gel filtration. In hemagglutination inhibition assays, it exhibits sugar-binding specificities towards GlcNAc beta 1-->4Man beta-pNP, Gal beta 1-->4GlcNAc beta 1-->4GlcNAc, and Gal beta 1-->4GlcNAc beta 1-->4GlcNAc beta 1-->4GlcNAc among mono- and oligosaccharides tested. Among glycoproteins tested, BSM and asialo-BSM were the strongest inhibitors.

Amanita↗
PubMed1995

A fruiting body-specific cDNA, mfbAc, from the mushroom Lentinus edodes encodes a high-molecular-weight cell-adhesion protein containing an Arg-Gly-Asp motif.

A cDNA clone (designated mfbAc), encoding 2157 amino acids (aa), was isolated from a mature fruiting-body cDNA library of the edible mushroom Lentinus edodes. The mfbA transcript was abundant in mature fruiting bodies, detectable in immature fruiting bodies but absent in earlier developmental stages and in the vegetative mycelium. Although more abundant in the pileus than the stipe, only low levels were found in the gill tissue. The deduced MFBA protein (234.5 kDa) contained a cell-surface attachment-promoting Arg-Gly-Asp (RGD) motif. MFBA was produced in Escherichia coli using a maltose-binding protein (MBP) fusion vector, but it was cleaved into four fragments even in a protease-deficient host. A 425-aa MFBA peptide containing the RGD motif (named MFBA(582-1006) peptide) was successfully produced using the phage T7 expression system. This MFBA(582-1006) peptide exhibited a cell adhesion and spreading activity toward mammalian cells. This activity of the MFBA fragment was competitively inhibited by the Gly-Arg-Gly-Asp-Ser-Pro peptide but not by the Gly-Arg-Gly-Glu-Ser-Pro peptide, showing that the RGD motif of MFBA is essential for the cell-binding activity.

Amino Acid Sequence↗
PubMed1996

Heterodimerization between two classes of homeodomain proteins in the mushroom Coprinus cinereus brings together potential DNA-binding and activation domains.

The A mating type-genes of the mushroom, Coprinus cinereus, encode two classes of homeodomain-containing proteins distinguished as HD1 and HD2 on the basis of conserved, but distinctly different motifs. Compatible mating partners bring together versions of the proteins that can heterodimerize, thereby generating an active transcription factor complex that commits mated cells to sexual development. We have previously described a rare mutation in which an HD2::HD1 gene fusion generates a 'fused dimer' lacking much of HD1 including the homeodomain yet capable of constitutively promoting development [Kües et al., EMBO J. 13 (1994b) 4054-4059]. Here, we exploit this mutation to help identify contributions made by each protein class to normal heterodimer function. We show that the HD2 homeodomain is essential; deletion within the HD1 homeodomain can be tolerated in a normal heterodimer, as well as in the mutant fusion protein, but not substitution of a critical amino acid. We define, by deletion analysis, an essential C-terminal region of the HD1 and demonstrate its potential activation function by the ability to activate transcription in yeast when fused to the GAL4 DNA-binding domain. We also identify a potential role in transcriptional repression for the predicted C-terminal helix of HD1 proteins.

Amino Acid Sequence↗
PubMed1982

Psilocybin and psilocin levels in twenty species from seven genera of wild mushrooms in the Pacific Northwest, U.S.A.

The analysis of twenty species from seven genera of Pacific Northwest mushrooms revealed psilocybin (and in some cases psilocin as well) in seven species from three genera. The species found to contain psilocybin (and psilocin) varied from one collection to another by more than a factor of seven in amount present. Total psilocybin and psilocin levels in species known to be in use for recreational and entheogenic purposes varied from 0.1% by dry weight up to a high of nearly 2% by dry weight.

Basidiomycota↗
PubMed2005

Analysis of the carbohydrate binding specificity of the mushroom Pleurotus ostreatus lectin by surface plasmon resonance.

The sugar binding specificity of the mushroom Pleurotus ostreatus lectin (POL) was analyzed by surface plasmon resonance. The lectin was immobilized to a sensor chip, and asialo-bovine submaxillary mucin (asialo-BSM), one of the most potent inhibitors in the hemagglutination inhibition assay, tightly bound to the lectin. The binding specificity of various mono- or oligosaccharides to the lectin was evaluated by the coinjection method. The dissociation of asialo-BSM was promoted by injection of some haptenic saccharides. For the most part, the order of acceleration ability of the sugars to the dissociation in the coinjection experiment agreed with that of the inhibitory potency of each sugar evaluated by the hemagglutination inhibition assay. In conclusion, POL recognized a galactosyl residue, and the specificity was increased by substitution at the C-2 position of the galactosyl residue with a fucosyl or acetylamino group. This method using the coinjection method proved useful in analysis of carbohydrate-lectin binding specificity.

Asialoglycoproteins↗
PubMed2004

Partial identification of carbohydrate-binding sites of a Galalpha1,3Galbeta1,4GlcNAc-specific lectin from the mushroom Marasmius oreades by site-directed mutagenesis.

The Galalpha1,3Galbeta1,4GlcNAc-specific lectin from the mushroom Marasmius oreades (MOA) contains a ricin B chain-like (QXW)(3) domain at its N-terminus that is composed of three identical subdomains (alpha, beta, and gamma) and a C-terminal domain of unknown function. Here, we investigate the structure-function relationship of MOA to define the number and location of its carbohydrate-binding sites. Based on the sequence alignment of MOA to the ricin B-chain lactose-binding sites, we systematically constructed mutants by site-directed mutagenesis. We have used precipitation and hemagglutination assay for the primary analyses, and surface plasmon resonance for the kinetic analysis. Among amino acid residues at the putative carbohydrate-binding sites, Gln(46) in the alpha subdomain and Trp(138) in the gamma subdomain have been identified to be important amino acid residues directly or indirectly involved in carbohydrate recognition. By surface plasmon resonance, Q46A and W138A were 2.4- and 4.3-fold less active than that of the wild-type MOA (K(a) = 2 x 10(7)), respectively. A double-site mutant (Q46A/W138A) had activity similar to W138A. The C-terminal deletion mutant MOADeltaC showed hemagglutination and precipitation activity, although its binding constant was 12.5-fold less active (K(a) = 1.6 x 10(6)) than that of the wild-type MOA. A C-terminal deletion mutant with mutations at both Gln(46) and Trp(138) (MOADeltaC-Q46A/W138A) was 12,500-fold less active (K(a) = 1.6 x 10(3)) than that of the wild-type MOA. On the basis of this observation, we conclude that both alpha and gamma subdomains are most probably involved in carbohydrate binding, but the beta subdomain appears to be inactive.

Agaricales↗
PubMed2005

Inverse mushroom-shaped nonmechanical penetrating keratoplasty using a femtosecond laser.

PURPOSE: To demonstrate the feasibility of an inverse mushroom-shaped nonmechanical corneal trephination using a femtosecond laser in a noncontact manner. DESIGN: Experimental study. METHODS: In this laboratory study, 10 polymethylmethacrylate (PMMA) blocks and 20 porcine corneas were treated with an industrial femtosecond laser source. The trephination profile consisted of (1) a 7- or 6-mm diameter cylinder from the anterior chamber, (2) an intermediate horizontal connecting plane, and (3) a concentric 5- or 4-mm diameter cylinder upwards. RESULTS: Applying appropriate combinations of pulse energy and spacing, trephination took less than 60 seconds. In porcine eyes, light microscopy displayed trephination edges delineated by partly confluent gas bubbles (10-40 mum) with tissue bridges in between. By TEM, the cut edges were lined by a delicate, electron-dense layer (5-40 nm). CONCLUSIONS: Femtosecond laser technology seems to offer a promising approach towards minimally invasive self-sealing "no-stitch keratoplasty."

Agaricales↗
PubMed2006

Influence of the soil bioavailability of radionuclides on the transfer of uranium and thorium to mushrooms.

The soil-mushroom transfer of thorium and uranium was analyzed in two ecologically similar but geographically separated Spanish ecosystems by means of the transfer factor, TF. Uranium TF values were in the range 0.043-0.49, and thorium TF values in the range 0.030-0.62. These values were similar to those of (90)Sr, (239+240)Pu, and (241)Am found previously in the same ecosystems. Given the low availability of uranium and thorium, the available transfer factors, ATF, were also determined. These were higher than the TF values by one order of magnitude for (234, 238)U, and by 2-3 orders of magnitude for (228, 230, 232)Th. The ATF value of thorium was similar to that of (137)Cs, and that of uranium similar to that of (40)K. Hebeloma cylindrosporum presented the highest uranium and thorium transfer factors, confirming this species as a good bioindicator of a soil's radioactive content.

Agaricales↗
PubMed2004

Interaction of mushroom tyrosinase with aromatic amines, o-diamines and o-aminophenols.

3-Amino-L-tyrosine was found to be a substrate of mushroom tyrosinase, contrary to what had previously been reported in the literature. A series of amino derivatives of benzoic acid were tested as substrates and inhibitors of the enzyme. 3-Amino-4-hydroxybenzoic acid, 4-amino-3-hydroxybenzoic acid and 3,4-diaminobenzoic acid were oxidized by this enzyme, as previously reported for Neurospora crassa tyrosinase, but 4-aminobenzoic acid and 3-aminobenzoic acid were not. Interestingly, 3-amino-4-hydroxybenzoic acid was oxidized five times faster than 4-amino-3-hydroxybenzoic acid, confirming the importance of proton transfer from the hydroxyl group at C-4 position. All compounds inhibited the monophenolase activity but their effect on the diphenolase activity was small or negligible. 3-Amino-4-hydroxybenzoic acid was a stronger inhibitor than 4-amino-3-hydroxybenzoic acid, indicating their different binding affinity to the oxy form of the enzyme. Both, however, were weaker inhibitors than 3-amino-L-tyrosine, 4-methoxy-o-phenylenediamine and 3,4-diaminobenzoic acid, which was the strongest inhibitor from among the compounds tested. These results show that the relative positioning of the amino group and the hydroxy group in o-aminophenols with respect to the side chain is important both for binding to the dicopper center and for catalysis.

Agaricales↗
PubMed2004

Substrate share in the suicide inactivation of mushroom tyrosinase.

To address the real cause of the suicide inactivation of mushroom tyrosinase (MT), under in vitro conditions, cresolase and catecholase reactions of this enzyme were investigated in the presence of three different pairs of substrates, which had been selected for their structural specifications. It was showed that the cresolase activity is more vulnerable to the inactivation. Acetylation of the free tyrosyl residues of MT did not cure susceptibility of the cresolase activity, but clearly decreased the inactivation rate of MT in the presence of 4-[(4-methylbenzo)azo]-1,2-benzenediol (MeBACat) as a catecholase substrate. Considering the results of the previous works and this research, some different possible reasons for the suicide inactivation of MT have been discussed. Accordingly, it was proposed that the interruption in the conformational changes in the tertiary and quaternary structures of MT, triggered by the substrate then mediated by the solvent molecules, might be the real reason for the suicide inactivation of the enzyme. However, minor causes like the toxic effect of the ortho-quinones on the protein body of the enzyme or the oxidation of some free tyrosyl residues on the surface of the enzyme by itself, which could boost the inactivation rate, should not be ignored.

Acetylation↗
PubMed2005

Inhibition kinetics of mushroom tyrosinase by copper-chelating ammonium tetrathiomolybdate.

With a strategy of chelating coppers at tyrosinase active site to detect an effective inhibitor, several copper-specific chelators were applied in this study. Ammonium tetrathiomolybdate (ATTM) among them, known as a drug for treating Wilson's disease, turned out to be a significant tyrosinase inhibitor. Treatment with ATTM on mushroom tyrosinase completely inactivated enzyme activity in a dose-dependent manner. Progress-of-substrate reaction kinetics using the two-step kinetic pathway and dilution of the ATTM revealed that ATTM is a tight-binding inhibitor and high dose of ATTM irreversibly inactivated tyrosinase. Progress-of-substrate reaction kinetics and activity restoration with a dilution of the ATTM indicated that the copper-chelating ATTM may bind slowly but reversibly to the active site without competition with substrate, and the enzyme-ATTM complex subsequently undergoes reversible conformational change, leading to complete inactivation of the tyrosinase activity. Thus, inhibition by ATTM on tyrosinase could be categorized as complexing type of inhibition with a slow and reversible binding. Detailed analysis of inhibition kinetics provided IC50 at the steady-state and inhibitor binding constant (K(I)) for ATTM as 1.0+/-0.2 microM and 10.65 microM, respectively. Our results may provide useful information regarding effective inhibitor of tyrosinase as whitening agents in the cosmetic industry.

Agaricales↗
PubMed2006

Purification and characterization of an N-acetyl-D-galactosamine-specific lectin from the edible mushroom Schizophyllum commune.

An N-acetyl-D-galactosamine (GalNAc)-specific lectin was purified from the edible mushroom, Schizophyllum commune, using affinity chromatography on a porcine stomach mucin (PSM)-Sepharose 4B column. Under reducing and non-reducing conditions, SDS-polyacrylamide gel electrophoresis gave a major band of 31.5 kDa. The Schizophyllum commune lectin (SCL) showed high affinity toward rat erythrocytes and the sugar inhibition assay exhibited its sugar specificity highly toward lactose and N-acetyl-D-galactosamine. It was stable at 55 degrees C for 30 min and at pH 3-10 for 18-h test. The lectin was shown to be a glycoprotein with cytotoxic activity against human epidermoid carcinoma cells. The N-terminus of SCL was blocked but amino acid sequences of internal tryptic peptides showed moderately sequence similarities with some other fungal and plant lectins. Crystals of SCL were obtained by the sitting drop vapour-diffusion method using polyethylene glycol 8000 as the precipitant, and gave an X-ray diffraction pattern to approximately 3.8 angstroms resolution.

Acetylgalactosamine↗
PubMed2006

Indirect oxidation of amino acid phenylhydrazides by mushroom tyrosinase.

We have investigated oxidation of amino acid phenylhydrazides by mushroom tyrosinase in the presence of 4-tert-butylcatechol and N-acetyl-L-tyrosine. Spectrophotometric measurements showed gradual disappearance of 4-tert-butyl-o-benzoquinone, generated by oxidation of 4-tert-butylcatechol with sodium periodate, after addition of amino acid phenylhydrazides. However, the presence of the phenylhydrazides did not influence the concentration of 4-tert-butyl-o-benzoquinone formed during enzymatic oxidation. Oxygen consumption measurements demonstrated that in a mixture both compounds were oxidized but the reaction rate was proportional to the concentration of the catechol. In the oxidation of N-acetyl-L-tyrosine addition of phenylhydrazides shortened the lag period, indicating that they acted as reducing agents, converting N-acetyl-L-dopaquinone to N-acetyl-L-dopa. In HPLC analysis of the oxidation 4-tert-butylcatechol and the phenylhydrazide of Boc-tryptophan only the N-protected amino acid and 4-tert-butyl-o-benzoquinone were detected as final products. In the presence of the natural substrates the oxidation of amino acid phenylhydrazides required much smaller amounts of the enzyme and was up to 40 times faster than the reaction carried out without these compounds. These results demonstrate that tyrosinase can oxidize phenylhydrazides indirectly through o-quinones. This reaction explains the inhibitory effect of agaritine, a natural amino acid hydrazide, on melanin formation and the inhibitory effects of other hydrazine derivatives on tyrosinase described in the literature.

Agaricales↗
PubMed2004

A homodimeric laccase with unique characteristics from the yellow mushroom Cantharellus cibarius.

The aim of the present study was to isolate a laccase from fruiting bodies of the yellow mushroom Cantharellus cibarius. The fruiting body extract was subjected to a purification protocol that involved ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel and Con A-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The laccase was unadsorbed on DEAE-cellulose and Affi-gel blue gel and adsorbed on Con A-Sepharose. The laccase was composed of two identical subunits each with a molecular mass of 46 kDa. The laccase exhibited a temperature-dependent rise in activity over the temperature range 20-50 degrees C. When the temperature was raised above 60 degrees C there was a fall in enzyme activity. The enzyme manifested maximal activity at pH 4. At and above pH 6 there was a dramatic reduction in activity. The unique features of this fruiting body laccase compared with previously reported mycelial laccases include homodimeric nature, a distinctive N-terminal sequence, a higher optimal pH, and adsorption on only ConA-Sepharose among the various chromatographic media tested.

Amino Acid Sequence↗