A novel lectin was isolated and characterized from Bryopsis plumosa (Hudson) Agardh and named BPL-3. This lectin showed specificity to N-acetyl-D-galactosamine as well as N-acetyl-D-glucosamine and agglutinated human erythrocytes of all blood types, showing slight preference to the type A. SDS-PAGE and MALDI-TOF MS data showed that BPL-3 was a monomeric protein with molecular weight of 11.5 kDa. BPL-3 was a non-glycoprotein with pI value of ∼7.0. It was stable in high temperatures up to 70°C and exhibited optimum activity in pH 5.5-10. The N-terminal and internal amino acid sequences of the lectin were determined by Edman degradation and enzymatic digestion, which showed no sequence homology to any other reported proteins. The full sequence of the cDNA encoding this lectin was obtained from PCR using cDNA library, and the degenerate primers were designed from the N-terminal amino acid sequence. The size of the cDNA was 622 bp containing single ORF encoding the lectin precursor. This lectin showed the same sugar specificity to previously reported lectin, Bryohealin, involved in protoplast regeneration of B. plumosa. However, the amino acid sequences of the two lectins were completely different. The homology analysis of the full cDNA sequence of BPL-3 showed that it might belong to H lectin group, which was originally isolated from Roman snails.
ABSTRACT. A field survey of algae and cyanobacteria from terrestrial and freshwater habitats in the vicinity of Ny-Ålesund and on Blomstrandhalvøya Island (Svalbard) was performed in June 2009, and results were compared with data from our fieldwork in June 2006. In total, we identified 30 taxa belonging to 23 genera from the specimens collected near Ny-Ålesund (26 taxa) and on Blomstrandhalvøya Island (24 taxa). Five species previously unrecorded from this locality are depicted, including astaxanthin-containing Haematococcus sp. collected from Blomstrandhalvøya Island. This is the first report on a Haematococcus species from the High Arctic.
Lectins have the ability to bind specific carbohydrates and they have potential applications as medical and pharmacological agents. The unique structure and usefulness of red algal lectin have been reported, but these lectins are limited to a few marine algal groups. In this study, a novel mannose-binding lectin from Grateloupia chiangii (G. chiangii lectin, GCL) was purified using antiviral screens and affinity chromatography. We characterized the molecular weight, agglutination activity, hemagglutination activity, and heat stability of GCL. To determine the carbohydrate specificity, a glycan microarray was performed. GCL showed strong binding affinity for Maltohexaose-β-Sp1 and Maltoheptaose-β-Sp1 with weak affinity for other monosaccharides and preferred binding to high-mannan structures. The N-terminal sequence and peptide sequence of GCL were determined using an Edman degradation method and LC-MS/MS, and the cDNA and peptide sequences were deduced. GCL was shown to consist of 231 amino acids (24.9 kDa) and the N-terminus methionine was eliminated after translation. GCL possessed a tandem repeat structure of six domains, similar to the other red algal lectins. The mannose binding properties and tandem repeat structure of GCL may confer it the potential to act as an antiviral agent for protection against viral infection.
Egg and sperm binding and correct recognition is the first stage for successful fertilization. In red algae, spermatial attachment to female trichogynes is mediated by a specific binding between the lectin(s) distributed on the surface of trichogyne and the complementary carbohydrates on the spermatial surface. A female-specific lectin was isolated from Aglaothamnion callophyllidicola by agarose-bound fetuin affinity chromatography. Two proteins, 50 and 14 kDa, eluted from the fetuin column were separated using a native-polyacrylamide gel electrophoresis method and subjected to a gamete binding assay. The 50 kDa protein, which blocked spermatial binding to female trichogynes, was used for further analysis. Internal amino acid sequence of the 50 kDa protein was analyzed using matrix-assisted laser desorption/ionization-mass spectrometry and degenerated primers were designed based on the information. A full-length cDNA encoding the lectin was obtained using rapid amplification of cDNA ends polymerase chain reaction (PCR). The cDNA was 1552 bp in length and coded for a protein of 450 amino acids with a deduced molecular mass of 50.7 kDa, which agreed well with the protein data. Real-time PCR analysis showed that this protein was up-regulated about 10-fold in female thalli. As the protein was novel and showed no significant homology to any known proteins, it was designated Rhodobindin.
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