A novel lectin (Morniga M) from mulberry (Morus nigra) bark recognizes oligomannosyl residues in N-glycans.

Morniga M is a jacalin-related and mannose-specific lectin isolated from the bark of the mulberry (Morus nigra). In order to understand the function and application of this novel lectin, the binding property of Morniga M was studied in detail using an enzyme-linked lectinosorbent assay and lectin-glycan inhibition assay with extended glycan/ligand collection. From the results, it was found that the di-, tri-, and oligomannosyl structural units of N-glycans such as those of the bovine alpha1-acid glycoprotein (gp) and lactoferrin were the most active gps, but not the O-glycans or polysaccharides including mannan from yeast.

Induction of cytoplasmic mannose-binding jacalin-related lectins is a common phenomenon in cereals treated with jasmonate methyl ester.

Treatment of whole plants with jasmonic acid methyl ester induces lectin activity in leaves of Oryza sativa, Hordeum vulgare, Triticum vulgare, Secale cereale and Zea mays. Purification and characterization of the lectins revealed that they all have a very similar molecular structure and carbohydrate-binding properties. Further analysis of the cDNA clones encoding the lectins revealed that they all belong to the family of cytoplasmic mannose-specific jacalin-related lectins.

Artocarpin is a polyspecific jacalin-related lectin with a monosaccharide preference for mannose.

A reinvestigation of the carbohydrate-binding properties revealed that artocarpin, a previously described mannose-specific lectin from jackfruit (Artocarpus integrifolia) seeds, behaves as a polyspecific lectin. Surface plasmon resonance hapten inhibition experiments demonstrated that artocarpin readily interacted with a wide range of monosaccharides covering galactose, N-acetylgalactosamine, mannose, glucose, sialic acid and N-acetylmuramic acid. Molecular docking confirmed this unexpected ability of artocarpin to interact with structurally different sugars.

Mannose-specific plant lectins from the Amaryllidaceae family qualify as efficient microbicides for prevention of human immunodeficiency virus infection.

The plant lectins derived from Galanthus nivalis (Snowdrop) (GNA) and Hippeastrum hybrid (Amaryllis) (HHA) selectively inhibited a wide variety of human immunodeficiency virus type 1 (HIV-1) and HIV-2 strains and clinical (CXCR4- and CCR5-using) isolates in different cell types. They also efficiently inhibited infection of T lymphocytes by a variety of mutant virus strains. GNA and HHA markedly prevented syncytium formation between persistently infected HUT-78/HIV cells and uninfected T lymphocytes.

Profile of resistance of human immunodeficiency virus to mannose-specific plant lectins.

The mannose-specific plant lectins from the Amaryllidaceae family (e.g., Hippeastrum sp.

The identification of inducible cytoplasmic/nuclear carbohydrate-binding proteins urges to develop novel concepts about the role of plant lectins.

During the last few years compelling evidence has been presented for the occurrence of cytoplasmic/nuclear plant lectins that are not detectable in normal plants but are only induced upon application of well-defined stress conditions. Since both the regulation of the expression and the subcellular location indicate that these 'non-classical lectins' are good candidates to play a physiologically important role as mediators of specific protein-carbohydrate-interactions within the plant cell, a critical assessment is made of the impact of these findings on the development of novel concepts about the role of plant lectins. Based on an analysis of the biochemical, molecular and evolutionary data of a jasmonate-induced chitin-binding lectin from tobacco leaves and a salt/jasmonate-induced leaf lectin from rice it is concluded that these lectins most probably interact with endogenous glycans located within the cytoplasmic/nuclear compartment of the plant cell.

The type-1 and type-2 ribosome-inactivating proteins from Iris confer transgenic tobacco plants local but not systemic protection against viruses.

The antiviral activity of the type-2 ribosome-inactivating protein (RIP) IRAb from Iris was analyzed by expressing IRAb in tobacco (Nicotiana tabacum L. cv. Samsun NN) plants and challenging the transgenic plants with tobacco mosaic virus (TMV).

Analysis of the in planta antiviral activity of elderberry ribosome-inactivating proteins.

Although the type-2 ribosome-inactivating proteins (SNA-I, SNA-V, SNLRP) from elderberry (Sambucus nigra L.) are all devoid of rRNA N-glycosylase activity towards plant ribosomes, some of them clearly show polynucleotide-adenosine glycosylase activity towards tobacco mosaic virus RNA. This particular substrate specificity was exploited to further unravel the mechanism underlying the in planta antiviral activity of ribosome-inactivating proteins.

Enzymatic activity of toxic and non-toxic type 2 ribosome-inactivating proteins.

Ribosome-inactivating proteins (RIPs) display adenine polynucleotide glycosylase activity on different nucleic acid substrates, which at the ribosomal level is responsible for the arrest of protein synthesis. Some type 2 RIPs, namely ricin and related proteins, are extremely toxic to mammalian cells and animals whilst other type 2 RIPs (non-toxic type 2 RIPs) display three to four logs less toxicity. We studied whether a correlation exists between toxicity on cells and enzymatic activity on nucleic acids.

Synergistic antifungal activity of two chitin-binding proteins from spindle tree (Euonymus europaeus L.).

Two structurally different chitin-binding proteins were isolated from bark and leaves of the spindle tree (Euonymus europaeus L.). Both the small hevein-like chitin-binding protein (Ee-CBP) and the classical class-I chitinase (Ee-chitinase) possess antifungal properties, Ee-CBP being far more potent than Ee-chitinase.

Potato lectin: an updated model of a unique chimeric plant protein.

A complete cDNA encoding a potato tuber lectin has been identified and sequenced. Based on the deduced amino acid sequence, the still enigmatic molecular structure of the classical chimeric potato lectin could eventually be determined. Basically, the potato lectin consists of two nearly identical chitin-binding modules, built up of two in-tandem arrayed hevein domains that are interconnected by an extensin-like domain of approximately 60 amino acid residues.

The crystal structure of the Calystegia sepium agglutinin reveals a novel quaternary arrangement of lectin subunits with a beta-prism fold.

The high number of quaternary structures observed for lectins highlights the important role of these oligomeric assemblies during carbohydrate recognition events. Although a large diversity in the mode of association of lectin subunits is frequently observed, the oligomeric assemblies of plant lectins display small variations within a single family. The crystal structure of the mannose-binding jacalin-related lectin from Calystegia sepium (Calsepa) has been determined at 1.

Classification of plant lectins in families of structurally and evolutionary related proteins.

The majority of plant lectins can be classified in seven families of structurally and evolutionary related proteins. Within a given lectin family most but not necessarily all members are built up of protomers with a similar primary structure and overall 3-D fold. The overall structure of the native lectins is not only determined by the structure of the protomers but depends also on the degree of oligomerization and in some cases on the post-translational processing of the lectin precursors.

The tomato lectin consists of two homologous chitin-binding modules separated by an extensin-like linker.

A cDNA encoding a putative lectin expressed in tomato leaves was identified and analysed. The lectin consists of two homologous chitin-binding modules interconnected by a short proline-rich domain containing a single Ser[Pro]( n ) repetitive motif. Each module comprises two in-tandem-arrayed hevein domains separated by a tetrapeptide linker.

The dead-end elimination method, tryptophan rotamers, and fluorescence lifetimes.

The Dead-End Elimination method was used to identify 40 low energy microconformations of 16 tryptophan residues in eight proteins. Single Trp-mutants of these proteins all show a double- or triple-exponential fluorescence decay. For ten of these lifetimes the corresponding rotameric state could be identified by comparing the bimolecular acrylamide quenching constant (k(q)) and the relative solvent exposure of the side chain in that microstate.

Colistin sulfate as a suitable substitute of thallium acetate in culture media intended for mycoplasma detection and culture.

Thallium acetate in concentrations of 500 to 1000 mg/l is tolerated in the culture by the most mollicutes of the orders Mycoplasmatales and Acholeplasmatales and by this reason it is added in the culture media as a selective element for the detection and propagation of mycoplasmas and acholeplasmas. Because of the high toxicity of thallium acetate and its accumulation in the environment, thallium acetate is not biodegradable, an alternative was searched. The results and analysis of tests with nine mollicute species are presented here.

Structural and functional characterization of the GalNAc/Gal-specific lectin from the phytopathogenic ascomycete Sclerotinia sclerotiorum (Lib.) de Bary.

The lectin found in mycelium and sclerotes of the phytopathogenic fungus Sclerotinia sclerotiorum is a homodimer consisting of two identical non-covalently bound subunits of 16,000 Da. CD spectra analysis revealed that the S. sclerotiorum agglutinin (SSA) contains predominantly beta-sheet structures.

The Tn antigen-specific lectin from ground ivy is an insecticidal protein with an unusual physiology.

Leaves of ground ivy (Glechoma hederacea) contain a lectin (called Gleheda) that is structurally and evolutionary related to the classical legume lectins. Screening of a population of wild plants revealed that Gleheda accounts for more than one-third of the total leaf protein in some clones, whereas it cannot be detected in other clones growing in the same environment. Gleheda is predominantly expressed in the leaves where it accumulates during early leaf maturation.

Lectin histochemistry of the lymphoid organs of the chicken.

Cellular interactions within the immune system are in part mediated via the carbohydrate-rich coat of the cell membrane, the glycocalyx, of which the terminal carbohydrate residues are of particular functional importance. Thus, these carbohydrate residues from thymus, bursa of Fabricius, spleen and bone marrow of 2- and 30-day-old chickens were investigated by lectin histochemistry. In the thymus, mannose as well as N-acetyl-glucosamine (glcNAc)-specific lectins labelled macrophages, epithelial reticulum cells and lymphocytes within the cortex.

A molecular basis for the endo-beta 1,3-glucanase activity of the thaumatin-like proteins from edible fruits.

Fruit-specific thaumatin-like proteins were isolated from cherry, apple and banana, and their enzymatic and antifungal activities compared. Both the apple and cherry possess a moderate endo-beta 1,3-glucanase activity but are devoid of antifugal activity. In contrast, the banana thaumatin-like protein inhibits the in vitro hyphal growth of Verticillium albo-atrum but is virtually devoid of endo-beta 1,3-glucanase activity.

A structural basis for the difference in specificity between the two jacalin-related lectins from mulberry (Morus nigra) bark.

The activity and specificity of a galactose-specific and a mannose-specific jacalin-related lectin from the bark of the black mulberry (Morus nigra) tree has been re-investigated using different experimental approaches. Both lectins definitely behave as polyspecific lectins recognizing galactose, mannose, and glucose even though MornigaG and MornigaM interact preferentially with galactose and mannose, respectively. The exceptionally extended size of the carbohydrate-binding site of both lectins apparently accounts for their polyspecific character.

Ee-CBP, a hevein-type antimicrobial peptide from bark of the spindle tree (Euonymus europaeus L.).

Ee-CBP, a hevein-type antimicrobial peptide was isolated from the bark of the spindle tree (Euonymus europaeus L.). This 4992.

Type-1 ribosome-inactivating protein from iris bulbs: a useful agronomic tool to engineer virus resistance?

To study the in planta antiviral activity of a type-1 ribosome-inactivating protein from iris bulbs, called IRIP, Nicotiana tabacum cv. Samsun NN was transformed with the IRIP sequence expressed under the control of the 35S cauliflower mosaic virus promoter. Molecular analysis of the transgenic plants and characterization of the purified protein revealed that the recombinant IRIP from tobacco leaves has the same molecular structure and RNA N-glycosidase activity as the native protein from iris bulbs.