High Mannose-binding Lectin with Preference for the Cluster of α1–2-Mannose from the Green Alga Boodlea coacta Is a Potent Entry Inhibitor of HIV-1 and Influenza Viruses

Abstract

The complete amino acid sequence of a lectin from the green alga Boodlea coacta (BCA), which was determined by a combination of Edman degradation of its peptide fragments and cDNA cloning, revealed the following: 1) B. coacta used a noncanonical genetic code (where TAA and TAG codons encode glutamine rather than a translation termination), and 2) BCA consisted of three internal tandem-repeated domains, each of which contains the sequence motif similar to the carbohydratebinding site of Galanthus nivalis agglutinin-related lectins. Carbohydrate binding specificity of BCA was examined by a centrifugal ultrafiltration-HPLC assay using 42 pyridylaminated oligosaccharides. BCA bound to high mannose-type N-glycans but not to the complex-type, hybrid-type core structure of N-glycans or oligosaccharides from glycolipids. This lectin had exclusive specificity for ␣1-2-linked mannose at the nonreducing terminus. The binding activity was enhanced as the number of terminal ␣1-2-linked mannose substitutions increased. Mannobiose, mannotriose, and mannopentaose were incapable of binding to BCA. Thus, BCA preferentially recognized the nonreducing terminal ␣1-2-mannose cluster as a primary target. As predicted from carbohydrate-binding propensity, this lectin inhibited the HIV-1 entry into the host cells at a half-maximal effective concentration of 8.

Biological activity, cDNA cloning and primary structure of lectin KSA-2 from the cultivated red alga Kappaphycus striatum (Schmitz) Doty ex Silva

“…This lectin family includes: OAA from Oscillatoria agardhii NIES-240 Sato and Hori, 2009;Koharudin et al, 2011), PFL from Pseudomonas fluorescens Pf0-1 (Sato et al, 2012), MBHA from Myxococcus xanthus (Koharudin et al, 2012), BOA from Burkholderia oklahomensis (Whitley et al, 2013), KAA-2 from Kappaphycus alvarezii (Sato et al, 2011a), BCA from Boodlea coacta (Sato et al, 2011b) and ESA-2 from Eucheuma serra (Sato et al, 2015). All of them share binding specificity for high-mannose N-glycans and have commonly two or four tandem repeats consisting of highly conserved sequences, which may lead to subtle difference in the degree of inhibiting activities.…”

Biological Applications of Plants and Algae Lectins: An Overview

“…The homology sequence analysis of BPL-3 showed that it might belong to H lectin group from Roman snails (Helix pomatia). The latest primary structure published was of lectin from Boodlea coacta (BCA) [105]. BCA consisted of 3 internal tandem-repeated domains, each one containing the sequence motif similar to the carbohydrate-binding site of land plant lectin from Galanthus nivalis.…”

The Difference of Lectin Recovery by Sugar-Bound Resin

“…They are classified into many groups based on amino acid sequences. For example, galectin, and C-type lectin are popular lectins (Kasai & Hirabayashi, 1996;Drickamer, 1999), and even today, various lectins with new structures are still being found in many animals, bacteria, and fungi ( Jimbo et al, 2005;Tateno et al, 1998;Jimbo et al, 2000;Sato et al, 2011).…”