Lectin Sequences Research Articles

Molecular characterization of mannose specific lectin gene,ASAL1 from Garlic leaf (Allium sativumL.)

Plant lectins, especially monocot mannose-binding lectins (MMBLs) play significant roles in plant defense against sap sucking insects. In the present study, lectin gene (ASAL1) from garlic leaves (Allium sativum L. leaf agglutinin) was isolated, sequenced and characterized using various bioinformatics tools. Full-length cDNA of naturally occurring MMBLs was synthesized from garlic leaf RNA (leaf agglutinin, ASAL1) using RT-PCR and was amplified with gene specific primers designed corresponding to the conserved regions of the nucleotide sequences of garlic lectin sequences already available at NCBI. The amplified cDNA was sequenced. Sequence analysis revealed 369bp ORF including C-terminal stop codon, encoding a putative polypeptide of 122 amino acids (13kD) in ASAL1. The candidate gene sequence (ASAL1) was 33 nucleotides more and showed eight nucleotide changes than the previously reported garlic leaf lectin gene sequence of 339bp with accession number EU252577. ASAL1 gene sequence showed maximum (98%) identity with Allium sativum lectin mRNA complete cds having accession number DQ525625.1. In ASAL1 nine amino acid residues were glycosylated (both N and O linked). A putative conserved domain (4–113) was detected in the deduced amino acid sequence. ASAL1 gene is bulb type mannose binding lectin (β-lectin). Phylogenetic analysis revealed that ASAL1 falls in close relation with ACA.

Electrochemical magnetoassay coupled to PCR as a quantitative approach to detect the soybean transgenic event GTS40-3-2 in foods

Simple, cost-effective and reliable tools for the quantification of genetically modified organisms (GMO) in food and feed are highly demanded to enforce labelling legislation in the EU. Herein, we report a novel method for quantitative analysis of genetically modified soybean with the event GTS-40-3-2, also known as Roundup Ready (RR) soybean, using magnetoassays with electrochemical detection, coupled to DNA amplification by end-point polymerase chain reaction (PCR). For the proposed work, two DNA sequences were targeted via hybridisation onto magnetic beads, one specific for the transgenic event and the other for the taxon or species-specific lectin gene. Enzymatic labelling was performed to obtain an electrochemically active product measured by chronoamperometry. By optimising the number of PCR cycles, among other parameters, two magnetoassays coupled to PCR were successfully accomplished and linearity was obtained in the ranges of 53–4425 and 1093–88,496 DNA copies for the event-specific and lectin sequences, respectively. The proposed method provides accurate and precise RR soybean quantitative results, being effectively compared to those obtained by real-time PCR, as the reference method. These findings confirm the suitability of the method as an alternative tool for GMO quantification.

Purification and Characterization of a Lectin from Green Split Peas (Pisum sativum).

Lectins have captured the attention of a large number of researchers on account of their various exploitable activities, including antitumor, immunomodulatory, antifungal, as well as HIV reverse transcriptase inhibitory activities. A mannose/glucose-specific lectin was isolated from green split peas (a variety of Pisum sativum) and characterized. The purification step involved anion-exchange chromatography on a DEAE-cellulose column, cation-exchange chromatography on an SP-Sepharose column, and gel filtration by fast protein liquid chromatography (FPLC) on Superdex 200. The purified lectin had a native molecular mass of around 50kDa as determined by size exclusion chromatography. It appeared as a heterotetramer, composed of two distinct polypeptide bands with a molecular mass of 6 and 19kDa, respectively, in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The N-terminal sequence of green split pea lectin shows some degree of homology compared to lectins from other legume species. Its hemagglutinating activity was inhibited by glucose, mannose, and sucrose, and attenuated at pH values higher than 12 or lower than 3. Hemagglutinating activity was preserved at temperatures lower than 80°C. The lectin did not show antifungal activity toward fungi including Fusarium oxysporum, Botrytis cinerea, and Mycosphaerella arachidicola. Green split pea lectin showed a mitogenic effect toward murine splenocytes and could inhibit the activity of HIV-1 reverse transcriptase.

English

Lectins have been well studied and proved to play important roles in plant defense but information of legume lectins from non-legume plants has been rarely reported. A new legume lectin gene, designated as SmL 1, was cloned from Salvia miltiorrhiza Bunge, a famous traditional Chinese medicinal plant. The cDNA of SmL 1 was 919 bp in length and contained an 822 bp open reading frame (ORF) encoding a putative lectin precursor with two legume lectin domains. The deduced SML1 protein of SmL 1 shared 29 to 43% identities with other legume lectin sequences. Real time PCR analysis revealed that SmL 1 was predominantly expressed in the leaves and could be induced by pathogens and MeJA. The recombinant protein (rSmL1) of SmL 1 in Escherichia coli M15 was purified and showed agglutination activity towards rabbit and mouse red blood cells, and anti-bacterial activity against E. coli (ATCC35218), Pseudomonas lachrymans (PSL) and Xanthomonas campestris pv. Campestris (Pammel) Dowson (XC-1). Based on these results, SmL1 could play a role in medicinal plant disease control. Keywords: Anti-Bacterial Activity, Gene Expression, Legume Lectin, Recombinant Protein, Salvia miltiorrhiza Bunge

The alum-processing mechanism attenuating toxicity of Araceae Pinellia ternata and Pinellia pedatisecta.

The present study aimed at investigating the alum-processing mechanism attenuating toxicity of Araceae Pinellia ternata and Pinellia pedatisecta. Animal retroperitoneal inflammatory model in vivo and macrophagocyte release inflammatory factor model in vitro were used to detect the effect of alum processing on raphides and lectin. Scanning electron microscopy was used to observe the change in raphides during processing; HPLC method was used to determine the correlation between the dissolution and corrosion of raphides and ion in the alum solution; (27)Al-NMR technology was used to detect the relationship between aluminum oxalate complex formation and the dissolved and corrosion of raphides. The change in protein peptide sequence of lectin during the processing of alum solution was determined by Shotgun LC-MS assay. Raphides induced severe rabbit conjunctival edema and an intraperitoneal injection of lectin increased PGE2 and protein in mice peritoneal exudate, while decreased after treatment with alum solution processing. During the processing raphides was dissolved and corroded, then its structure was damaged. Raphides was soaked in the alum solution and significantly decreased the oxalate content, and the effect was related with Al(3+) in the alum. Al(3+) in the alum combined with C2O4(2-) of raphides into a stable complex compound promoted the dissolution of calcium oxalate. Raphides soaked in the alum made lectin proteins dissolve, whereas protein peptide sequence of lectin was changed and the protein structure was damaged. Alum solution could decrease the toxicity of P. ternata (Thunb.) Breit. and P. pedatisecta Schott. Since it made a special crystal structure of raphides damage and the protein of lectin dissolve. The structure of toxic substances significantly changed, which decreased the inflammatory effect.

Development and application of a multi-targeting reference plasmid as calibrator for analysis of five genetically modified soybean events.

Reference materials are important in accurate analysis of genetically modified organism (GMO) contents in food/feeds, and development of novel reference plasmid is a new trend in the research of GMO reference materials. Herein, we constructed a novel multi-targeting plasmid, pSOY, which contained seven event-specific sequences of five GM soybeans (MON89788-5', A2704-12-3', A5547-127-3', DP356043-5', DP305423-3', A2704-12-5', and A5547-127-5') and sequence of soybean endogenous reference gene Lectin. We evaluated the specificity, limit of detection and quantification, and applicability of pSOY in both qualitative and quantitative PCR analyses. The limit of detection (LOD) was as low as 20 copies in qualitative PCR, and the limit of quantification (LOQ) in quantitative PCR was 10 copies. In quantitative real-time PCR analysis, the PCR efficiencies of all event-specific and Lectin assays were higher than 90%, and the squared regression coefficients (R(2)) were more than 0.999. The quantification bias varied from 0.21% to 19.29%, and the relative standard deviations were from 1.08% to 9.84% in simulated samples analysis. All the results demonstrated that the developed multi-targeting plasmid, pSOY, was a credible substitute of matrix reference materials, and could be used as a reliable reference calibrator in the identification and quantification of multiple GM soybean events.

Novel unfolding sequence of banana lectin: Folded, unfolded and natively unfolded-like monomeric states in guanidine hydrochloride

The sequence of unfolding events of dimeric banana lectin (Banlec), as induced by guanidine hydrochloride (GdnHCl), has been investigated by size-exclusion HPLC, fluorescence, far-UV CD, low temperature phosphorescence and selective chemical modification. 8-Anilino-1-naphthalenesulfonate (ANS) binding indicates a structured unfolding intermediate which has been characterized as dissociated monomer by size-exclusion chromatography. Interestingly, the unfolding elution pattern reveals two distinct unfolded states. One is a usual random coil. The other represents a novel species having elution behavior and structural compactness (Stokes radius) similar to dissociated monomer but showing no regular secondary structure as determined by far-UV CD, thus resembling a natively unfolded state. N-Bromosuccinimide (NBS) oxidation shows that single tryptophan residue remains unmodified in dissociated monomer intermediate while the same is oxidized in natively unfolded-like species. Such difference in tryptophan environment in these species is supported by acrylamide quenching studies, and phosphorescence results at 77K which show a blue-shift of (0,0) band from 414.8nm to 409.2nm. The present results reveal subtlety of structural characteristics of unfolded states of Banlec in GdnHCl, which provide important insight in protein unfolding reaction.

A Hemagglutinin from Northeast Red Beans with Immunomodulatory Activity and Anti-proliferative and Apoptosis-inducing Activities Toward Tumor Cells

A 64-kDa hemagglutinin from a Phaseolus vulgaris cultivar, the northeast red bean, was purified by a protocol composed of three chromatographic steps involving affinity chromatography on Affi-gel blue gel, cation exchange chromatography on SP-Sepharose and FPLC-gel filtration on Superdex 75. The purified hemagglutinin appeared as a single 32-kDa band in SDS-PAGE indicating its dimeric nature. The N-terminal amino acid sequence of the hemagglutinin resembled the sequences of lectins and hemagglutinins from a number of Phaseolus species. The hemagglutinin manifested moderate thermostability and pH stability. It retained full activity up to 65 °C and in the pH range 2-12. It did not interact with simple sugars such as glucose, mannose and galactose. The hemagglutinin exerted immunostimulatory effects by upregulating the expression of cytokines like interferon-γ and tumor necrosis factor-α. It also exhibited antiproliferative activity on a number of tumor cells including MCF7 (breast cancer), HepG2 (liver cancer), CNE1 and CNE2 (nasopharyngeal cancer) cells, with stronger activity toward MCF7 and CNE1 cells. The hemagglutinin induced phophatidylserine externalization, mitochondrial depolarization and DNA condensation in MCF7 cells, indicating initiation of apoptosis. However, at high hemagglutinin concentrations, severe damage to the MCF7 cells was detected.

Comparison of venom composition and biological activities of the subspecies Crotalus lepidus lepidus, Crotalus lepidus klauberi and Crotalus lepidus morulus from Mexico

The rock rattlesnakes Crotalus lepidus comprise a group (lepidus, klauberi, morulus and maculosus) of poorly known mountain cold-tolerant snakes in Mexico. In particular, Crotalus lepidus morulus is a snake endemic of the northeast of Mexico, whereas Crotalus lepidus klauberi and C. l. lepidus are distributed in some regions of the north and central Mexico and southern U. S. Until now very little data are available from C. lepidus subspecies from Mexico, as the terrain inhabited by these snakes is generally steep and rugged. In this work, we have determined some biochemical and biological properties of C. l. morulus, C. l. klauberi and C. l. lepidus crude venoms. Some minor differences in venoms were noted in SDS-PAGE, HPLC profile and MALDI-TOF mass spectrometry analysis. Partial sequences of metalloproteinases, phospholipases A2 (PLA2) and galactose-specific lectins were identified in the venoms. Venoms of C. l. klauberi and C. l. lepidus had significantly higher hemorrhagic and lethal activities than C. l. morulus venom. Proteolytic activity in azocasein was higher in C. l. morulus venom, whereas gelatin hydrolysis was higher in C. l. klauberi. Fibrinogenolytic and PLA2 activities were very similar in all venoms tested. The histological observations in the gastrocnemius muscle damaged by venoms from all the subspecies confirmed myonecrotic and hemorrhagic activities (at 3 and 24 h), which resulted in a poor regenerative response after 14 days. However, C. l. lepidus and C. l. klauberi venom induced a higher increase in the plasma activity of creatine kinase (CK), evidencing higher myotoxicity, whereas paw edema-inducing activity was higher in C. l. lepidus venom. The results indicate that the venoms from the three subspecies have similar protein profiles in electrophoresis, HPLC and molecular weight determinations. However, differences were found in the biological activities in mice. Notably, the venoms of C. l. lepidus and C. l. klauberi present higher toxicity (lower LD50) and hemorrhagic activity than C. l. morulus venom.

Purification and Characterization of a Novel Lectin with Antiphytovirus Activities from the wild Mushroom Paxillus involutus

A novel lectin was isolated from the dried fruiting bodies of the wild mushroom Paxillus involutus. Isolation was conducted by anion exchange chromatography on DEAE-Cellulose, Q-Sepharose and gel filtration on Superdex 75 using a fast protein liquid chromatography (FPLC) system. This lectin had a molecular mass of 28 kDa and was composed of four identical subunits, each with a molecular mass of 7 kDa. N-terminal amino acid sequence of the P. involutus lectin was determined to be CTCAVFLNNTTVKS, which showed a low level of similarity to mushroom lectin sequences reported previously. The biochemical properties of this lectin were determined, and the hemagglutinating activity was inhibited by inulin and O-Nitrophenyl-β-D-galacto-pyranoside. Additionally, Ca2+, Zn2+, Cd2+, Fe2+, and Al3+ inhibited its hemagglutinating activity, while Cu2+ promoted this activity. This lectin exhibited poor thermostability and was sensitive to HCl, but it had a high tolerance to NaOH exposure. In terms of biological properties, this lectin manifested antiphytovirus activity towards tobacco mosaic virus (TMV) with a 70.61% inhibition at a concentration of 200 µg/mL. This lectin was devoid of inhibitory activities toward pathogenic fungi and HIV-1 reverse transcriptase, and antiproliferative activities were observed in tumor cell lines including lung cancer A-549 and human colon cancer HCT-8 cells.

ISOLATION AND IDENTIFICATION OF LECTIN GENE IN LICORICE, Glycorrhiza glabra L., PLANT IN EGYPT

Lectins are a group of nonenzymatic carbohydrate-binding proteins that are present in plants, animals and microorganisms. In the present study, DNA was extracted from the dried roots of licorice and seeds of green pea plants (positive control). Specific PCR technique was employed using specific primers (Lec1 and Lec2) for the amplification of Lectin gene. The amplified fragment mol. Size was about 700 bp that was cloned and sub-cloned into the pPROEXHTa expression vector. The purified proteins were separated at 27 and 30 KDa in both licorice and green pea plants, respectively, using SDS-PAGE. Sequencing of the PCR product of lectin gene was documented into the Genbank under the accession numbers HQ337023 and HQ337024 for licorice and green peas plants, respectively. The comparison of nucleotide sequence of the root Lectin gene from Licorice under study showed complete similarity (100%) to partial lectin 2 gene from Licorice that accession number (AJ234389) while, lectin sequence from seeds of green peas was clearly shared 100% nucleotide identity with a lectin (psl), complete cds and lecA genes from green pea with their accession numbers EU825771 and T00440, respectively, also, it showed nucleotide sequence identity of 98%. to the P. sativum psl lectin gene (xx66368) and Pea psl gene encoding Lectin complete cds (M18160) with identity of 92%.

Smelt was the likely beneficiary of an antifreeze gene laterally transferred between fishes

BackgroundType II antifreeze protein (AFP) from the rainbow smelt, Osmerus mordax, is a calcium-dependent C-type lectin homolog, similar to the AFPs from herring and sea raven. While C-type lectins are ubiquitous, type II AFPs are only found in a few species in three widely separated branches of teleost fishes. Furthermore, several other non-homologous AFPs are found in intervening species. We have previously postulated that this sporadic distribution has resulted from lateral gene transfer. The alternative hypothesis, that the AFP evolved from a lectin present in a shared ancestor and that this gene was lost in most species, is not favored because both the exon and intron sequences are highly conserved.ResultsHere we have sequenced and annotated a 160 kb smelt BAC clone containing a centrally-located AFP gene along with 14 other genes. Quantitative PCR indicates that there is but a single copy of this gene within the smelt genome, which is atypical for fish AFP genes. The corresponding syntenic region has been identified and searched in a number of other species and found to be devoid of lectin or AFP sequences. Unlike the introns of the AFP gene, the intronic sequences of the flanking genes are not conserved between species. As well, the rate and pattern of mutation in the AFP gene are radically different from those seen in other smelt and herring genes.ConclusionsThese results provide stand-alone support for an example of lateral gene transfer between vertebrate species. They should further inform the debate about genetically modified organisms by showing that gene transfer between ‘higher’ eukaryotes can occur naturally. Analysis of the syntenic regions from several fishes strongly suggests that the smelt acquired the AFP gene from the herring.

Purification and characterization of a mannose/N‐acetyl‐ d‐glucosamine‐specific lectin from the seeds of Platymiscium floribundum Vogel

Platymiscium floribundum lectin (PFL), a mannose/N-acetyl-D-glucosamine-specific lectin, was isolated from P. floribundum seeds using Sepharose-mannose affinity media chromatography. PFL is a glycoprotein that is a potent agglutinin for rabbit erythrocytes. In addition, PFL is highly stable because it is able to maintain its hemagglutinating activity after exposure to temperatures of up to 60 °C for 1 h and exposure to a wide pH range. The PFL purification process was monitored using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the results showed that the purified lectin consists of a single band with a molecular mass of approximately 29 kDa in either the presence or the absence of a reducing agent. The analysis of purified PFL by electrospray ionization-mass spectrometry showed that most ions had a molecular weight of 27,053 ± 2 Da, and other less abundant ions had similar molecular weights. Gel filtration shows that the lectin exists as a dimer in solution with mass at approximately 65 kDa. Sixteen peptides were sequenced, and as a result, a total of 130 amino acids were identified and resulted in a coverage of approximately 65% of the PFL sequence. The partial sequence of PFL was aligned with sequences of other lectins from evolutionarily related species, and PFL showed considerable similarity to the other lectins.

Development and verification of PCR based assay to dectect and quantify garden pea lec gene

Genetically modified organisms (GMOs) entering the food chain have became its part, which is necessary to monitor. GMO analyses are used as a control mechanism according to valid acquis communautaire for traceability and labeling of GMOs. Generally, approved PCR based protocols are used and they require stepwise procedures that use amplification of species specific gene as initial point. This study aims to develop and verify PCR based assay for amplification of garden pea lectin gene (Pisum sativum L.) as reference one. Lectin gene was analysed in silico, selected region was amplified and sequenced and new set of species specific primers for identification of garden pea was designed. Conditions of conventional PCR as well as real-time PCR were optimised and specificity of new primer set on DNA extracted from garden pea cultivars as well as DNA extracted from other selected species from Fabaceae family was tested. Quantification of garden pea lectin gene using real-time PCR based on SYBR Green I was optimised and performance characteristics recorded. The characteristics fit to method acceptance criteria range. Plasmid with garden pea lectin sequence was developed and plasmid is available as a positive control.   

Isolation and determination of the primary structure of a lectin protein from the serum of the American alligator (Alligator mississippiensis)

Mass spectrometry in conjunction with de novo sequencing was used to determine the amino acid sequence of a 35kDa lectin protein isolated from the serum of the American alligator that exhibits binding to mannose. The protein N-terminal sequence was determined using Edman degradation and enzymatic digestion with different proteases was used to generate peptide fragments for analysis by liquid chromatography tandem mass spectrometry (LC MS/MS). Separate analysis of the protein digests with multiple enzymes enhanced the protein sequence coverage. De novo sequencing was accomplished using MASCOT Distiller and PEAKS software and the sequences were searched against the NCBI database using MASCOT and BLAST to identify homologous peptides. MS analysis of the intact protein indicated that it is present primarily as monomer and dimer in vitro. The isolated 35kDa protein was ~98% sequenced and found to have 313 amino acids and nine cysteine residues and was identified as an alligator lectin. The alligator lectin sequence was aligned with other lectin sequences using DIALIGN and ClustalW software and was found to exhibit 58% and 59% similarity to both human and mouse intelectin-1. The alligator lectin exhibited strong binding affinities toward mannan and mannose as compared to other tested carbohydrates.

Expression analysis of the nucleocytoplasmic lectin ‘Orysata’ from rice in Pichia pastoris

The Oryza sativa lectin, abbreviated Orysata, is a mannose-specific, jacalin-related lectin expressed in rice plants after exposure to certain stress conditions. Expression of a fusion construct containing the rice lectin sequence linked to enhanced green fluorescent protein in Bright Yellow 2 tobacco cells revealed that Orysata is located in the nucleus and the cytoplasm of the plant cell, indicating that it belongs to the class of nucleocytoplasmic jacalin-related lectins. Since the expression level of Orysata in rice tissues is very low the lectin was expressed in the methylotrophic yeast Pichia pastoris with the Saccharomyces α-factor sequence to direct the recombinant protein into the secretory pathway and express the protein into the medium. Approximately 12 mg of recombinant lectin was purified per liter medium. SDS/PAGE and western blot analysis showed that the recombinant lectin exists in two molecular forms. Far western blot analysis revealed that the 23 kDa lectin polypeptide contains an N-glycan which is absent in the 18.5 kDa polypeptide. Characterization of the glycans present in the recombinant Orysata revealed high-mannose structures, Man9-11 glycans being the most abundant. Glycan array analysis showed that Orysata interacts with high-mannose as well as with more complex N-glycan structures. Orysata has potent anti-human immunodeficiency virus and anti-respiratory syncytial virus activity in cell culture compared with other jacalin-related lectins.

BIOACTIVITY AND CLONING OF A NEW ANTIBACTERIAL LECTIN PROTEIN IN SPONGE <i>Gelliodes</i> sp. FROM BARANGLOMPO ISLAND IN SOUTH SULAWESI INDONESIA TERRESTRIAL

A research on antibacterial bioactivity of protein fraction isolated from several species of sponges of Barang Lompo Island has been conducted. Pre-purification of protein using fractional method, showed maximum bioactivity with the inhibition zone of 26 mm to Salmonella typhy from sponge Gelliodes sp. with the saturation level of ammonium sulfate of 40-60%. Further purification of this fraction using column chromatography followed by protein sequencing, indicated that pure protein as lectin, and behaves as a single-band on SDS-PAGE with molecular weight of 21 kDa. Based on amino acids partial sequence, we cloned and sequenced cDNA encoding lectin protein. It consists of 552 nucleotides encoding 183 amino acid residues including a putative initiation Met. To obtain it in large amounts, the coding sequence of lectin was cloned into pGEX-2TK vector and expression as a lectin fusion protein in Escherichia coli. Recombinant lectin exhibited a similar antibacterial activity to the native lectin. The recombinant lectin had stronger antibacterial activity toward S. typhy and S. aureus (G+) with the diameters of inhibition zone were 16 mm and 17 mm, respectively. This research might provide significant results for the following research on the antibacterial action in molecular level of lectin protein from marine sponges. Keywords: sponge, Gelliodes sp., lectin, Recombinant protein, antibacterial activity

Crystal structures of a novel anti-HIV mannose-binding lectin from Polygonatum cyrtonema Hua with unique ligand-binding property and super-structure

Polygonatum cyrtonema lectin (PCL) is a novel anti-HIV mannose-binding lectin from Galanthus nivalis agglutinin (GNA)-related lectin family. Crystal structures of ligand-free PCL and its complexes with monomannoside and alpha1-3 dimannoside have been determined. The ligand-free PCL is dimeric, with both subunits adopt the beta-prism II fold. PCL subunit binds mannose using a potential bivalent mode instead of the usual trivalent mode, in which carbohydrate-binding site (CBS) I and CBS III adopt the conserved mannose-binding motif of QXDXNXVXY (X is one of any amino acid residues) as observed in other structurally characterized GNA-related lectins, while CBS II adopts a modified motif with residues Gln58 and Asp60, which are critical for mannose-binding, substituted by His58 and Asn60, respectively. As a result, CBS II is unfit for mannose-binding. In the mannoside complexes, ligand-bindings only occur at CBS I which provides the specificity for alpha1-3 dimannoside. CBS II and CBS III are cooperatively occupied by a well-ordered sulfate ion, through which the individual dimers are cross-linked to form a unique super-structure of 3(2) helical lattice. Surveying the sequences of GNA-related lectins revealed that the modified binding motif of CBS II is widely distributed in the Liliaceae family as an intrinsic structural element. There is evidence that other GNA-related lectins will also adopt the similar super-structure as PCL. Thus PCL structure, unique in ligand-binding mode, may represent a novel type of structure of GNA-related lectins. Comparative analyses indicated that the dimer-based super-structure may play a primary role in the anti-HIV property of PCL.

A novel lectin with antiproliferative activity from the medicinal mushroom Pholiota adiposa.

Little was known about biological activities of compounds from the medicinal mushroom of the genus Pholiota. A lectin from the Pholiota adiposa has now been isolated and its properties tested. The isolation procedure included ion exchange chromatography on DEAE-cellulose and CM-cellulose, and fast protein liquid chromatography-gel filtration (FPLC) on Superdex 75. The lectin was composed of two identical subunits, each with a molecular mass of 16 kDa. Its N-terminal amino-acid sequence showed little similarity to sequences of other Agaricales lectins. The hemagglutinating activity of the lectin was stable at temperatures up to 50 degrees C, and in NaOH and HCl solutions with concentrations less than 25 mM. It was inhibited by inulin (12.5-200 mM), but enhanced by Cu(2+) (6.25-25 mM), Fe(2+) (12.5-25 mM), and Al(3+) (6.25-25 mM) ions. The lectin showed antiproliferative activity toward hepatoma Hep G2 cells and breast cancer MCF7 cells with an IC(50) of 2.1 microM and approximately 3.2 microM, respectively. It exhibited HIV-1 reverse transcriptase inhibitory activity with an IC(50) of 1.9 microM. When compared with P. aurivella lectin, the only Pholiota lectin published to date, P. adiposa lectin differs in chromatographic behavior, molecular mass, N-terminal sequence, and effect of cations on hemagglutinating activity. In the case of the lectin from P. aurivella, its antifungal, antiproliferative, and HIV-1 reverse transcriptase inhibitory activities have not been determined.

Mannose-Binding Lectin from Yam (Dioscorea batatas) Tubers with Insecticidal Properties againstHelicoverpa armigera(Lepidoptera: Noctuidae)

The amino acid sequence of mannose-binding lectin, named DB1, from the yam (Dioscorea batatas, synonym Dioscorea polystachya) tubers was determined. The lectin was composed of two isoforms DB1(Cys86) and DB1(Leu86) consisting of 108 amino acid residues with 90% sequence homology between them. DB1 showed a high sequence similarity to snowdrop (Galanthus nivalis) bulb lectin, GNA; especially, the carbohydrate-binding sites of GNA were highly conserved in DB1. DB1 interacted with D-mannose residues of oligosaccharides, and the oligosaccharides carrying two mannose-alpha-1,3-D-mannose units showed high binding affinity. DB1 was examined for insecticidal activity against Helicoverpa armigera (Lepidoptera: Noctuidae) larvae at different stages of development. The rate of adults successfully emerging from pupae fed on DB1 was 33%, when incorporated into an artificial diet at a level of 0.01% (w/w). Although DB1 had no or marginal inhibitory effects on gut proteolytic and glycolic enzymes, the lectin strongly bound to larval brush border and peritrophic membrane detected by immunostaining. The results show that DB1 may fulfill a defense role against insect pests.