The crystal structure of the Calystegia sepium agglutinin reveals a novel quaternary arrangement of lectin subunits with a beta-prism fold. (1/7)

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 1.37-A resolution. Calsepa exhibits the same beta-prism fold as identified previously for other members of the family, but the shape and the hydrophobic character of its carbohydrate-binding site is unlike that of other members, consistent with surface plasmon resonance analysis showing a preference for methylated sugars. Calsepa reveals a novel dimeric assembly markedly dissimilar to those described earlier for Heltuba and jacalin but mimics the canonical 12-stranded beta-sandwich dimer found in legume lectins. The present structure exemplifies the adaptability of the beta-prism building block in the evolution of plant lectins and highlights the biological role of these quaternary structures for carbohydrate recognition.  (+info)

Isolation and characterization of bacteria associated with two sand dune plant species, Calystegia soldanella and Elymus mollis. (2/7)

Little is known about the bacterial communities associated with the plants inhabiting sand dune ecosystems. In this study, the bacterial populations associated with two major sand dune plant species, Calystegia soldanella (beach morning glory) and Elymus mollis (wild rye), growing along the costal areas in Tae-An, Chungnam Province, were analyzed using a culture-dependent approach. A total of 212 bacteria were isolated from the root and rhizosphere samples of the two plants, and subjected to further analysis. Based on the analysis of the 16S rDNA sequences, all the bacterial isolates were classified into six major phyla of the domain Bacteria. Significant differences were observed between the two plant species, and also between the rhizospheric and root endophytic communities. The isolates from the rhizosphere of the two plant species were assigned to 27 different established genera, and the root endophytic bacteria were assigned to 21. Members of the phylum Gammaproteobacteria, notably the Pseudomonas species, comprised the majority of both the rhizospheric and endophytic bacteria, followed by members of Bacteroidetes and Firmicutes in the rhizosphere and Alphaproteobacteria and Bacteroidetes in the root. A number of isolates were recognized as potentially novel bacterial taxa. Fifteen out of 27 bacterial genera were commonly found in the rhizosphere of both plants, which was comparable to 3 out of 21 common genera in the root, implying the host specificity for endophytic populations. This study of the diversity of culturable rhizospheric and endophytic bacteria has provided the basis for further investigation aimed at the selection of microbes for the facilitation of plant growth.  (+info)

Chryseobacterium soldanellicola sp. nov. and Chryseobacterium taeanense sp. nov., isolated from roots of sand-dune plants. (3/7)

Two Gram-negative, yellow-pigmented bacteria designated PSD1-4T and PHA3-4T, isolated from two sand-dune plant species inhabiting coastal areas in Tae-an, Korea, were subjected to taxonomic investigation. 16S rRNA gene sequence analysis indicated that both isolates should be placed in the genus Chryseobacterium of the family Flavobacteriaceae. The phenotypic properties of the strains were also consistent with their classification into this genus. The levels of 16S rRNA gene sequence similarity between strain PSD1-4T and other Chryseobacterium species were 95.2-97.2%; those between PHA3-4T and others were 93.7-97.8%. The DNA-DNA relatedness data indicated that strains PSD1-4T and PHA3-4T were clearly different from the nearest species, Chryseobacterium indoltheticum and Chryseobacterium taichungense. The major fatty acids were 13-methyltetradecanoic acid (iso-C15:0), 3-hydroxy-15-methylhexadecanoic acid (iso-C17:0 3-OH) and omega-9-cis-15-methylhexadecenoic acid (iso-C17:1omega9c) for both strains. On the basis of polyphasic taxonomic analysis results, it is evident that each of these strains represents a novel species of Chryseobacterium, for which the names Chryseobacterium soldanellicola sp. nov. (type strain PSD1-4T=KCTC 12382T=NBRC 100864T) and Chryseobacterium taeanense sp. nov. (type strain PHA3-4T=KCTC 12381T=NBRC 100863T) are proposed.  (+info)

Nucleotide sequence variability of the Adh gene of the coastal plant Calystegia soldanella (Convolvulaceae) in Japan. (4/7)

Calystegia soldanella (Convolvulaceae) is a self-incompatible perennial herb distributed on sandy seashores throughout the temperate zone of the world. In Japan, the species occasionally grows on the sandy shores of Lake Biwa. To clarify the genetic differentiation among local populations, we investigated the nucleotide sequence variability of the Adh gene. In a 1625-bp sequence between exon 2 and the 3' noncoding region of the Adh gene, a total of 44 polymorphic sites were found among 91 individuals from 19 populations. The nucleotide diversity for the entire sample was 0.00212. Similar values were determined for geographical groups of populations. No genetic differentiation among the groups of populations was found. The complete lack of genetic differentiation between the sea coastal populations and the inland populations could not be attributed to gene flow. Although the inland populations are geographically isolated from the sea coastal populations, the time since separation might be insufficient to establish significant genetic differentiation.  (+info)

Identification and characterization of component organic and glycosidic acids of crude resin glycoside fraction from Calystegia soldanella. (5/7)

Alkaline hydrolysis of the crude resin glycoside fraction of the leaves, stems, and roots of Calystegia soldanella ROEM. et SCHULT. (Convolvulaceae) gave four new glycosidic acids, named calysolic acids A, B, C, and D, along with one known glycosidic acid, soldanellic acid B, and three organic acids, 2S-methylbutyric, tiglic, and 2S,3S-nilic acids. The structures of the new glycosidic acids were characterized on the basis of spectroscopic data and chemical evidence.  (+info)

Quaternary association in beta-prism I2 fold plant lectins: insights from X-ray crystallography, modelling and molecular dynamics. (6/7)

Dimeric banana lectin and calsepa, tetrameric artocarpin and octameric heltuba are mannose-specific beta-prism I fold lectins of nearly the same tertiary structure. MD simulations on individual subunits and the oligomers provide insights into the changes in the structure brought about in the protomers on oligomerization, including swapping of the N-terminal stretch in one instance. The regions that undergo changes also tend to exhibit dynamic flexibility during MD simulations. The internal symmetries of individual oligomers are substantially retained during the calculations. Energy minimization and simulations were also carried out on models using all possible oligomers by employing the four different protomers. The unique dimerization pattern observed in calsepa could be traced to unique substitutions in a peptide stretch involved in dimerization. The impossibility of a specific mode of oligomerization involving a particular protomer is often expressed in terms of unacceptable steric contacts or dissociation of the oligomer during simulations. The calculations also led to a rationale for the observation of a heltuba tetramer in solution although the lectin exists as an octamer in the crystal, in addition to providing insights into relations among evolution, oligomerization and ligand binding.  (+info)

Calysolins V-IX, resin glycosides from Calystegia soldanella and their antiviral activity toward herpes. (7/7)

Five new resin glycosides having macrolactone structures (jalapins), named calysolins V-IX (1-5), were isolated from the leaves, stems, and roots of Calystegia soldanella ROEM. et SCHULT. (Convolvulaceae). Their structures were determined on the basis of spectroscopic data as well as chemical evidence. The isolated compounds could be classified into two macrolactone types-one having a 22-membered ring (1-4) and the other with a 27-membered ring (5). The sugar moieties of 1-5 were found to exist in partially acylated forms comprising 2S-methylbutyric acid and tiglic acid. Compounds 4 and 5 are the first representatives of the calysolic acid C as the component glycosidic acid. Additionally, the antiviral activity of 1-5, together with calysolins I-IV and soldanelline B, which are previously isolated jalapins from this plant, toward herpes simplex virus type 1 was evaluated. All the compounds showed antiviral activity.  (+info)