title: High-Mannose Specific Lectin and Its Recombinants from a Carrageenophyta Kappaphycus alvarezii Represent a Potent Anti-HIV Activity Through High-Affinity Binding to the Viral Envelope Glycoprotein gp120.
abstract: We previously reported that a high-mannose binding lectin KAA-2 from the red alga Kappaphycus alvarezii, which is an economically important species and widely cultivated as a source of carrageenans, had a potent anti-influenza virus activity. In this study, the full-length sequences of two KAA isoforms, KAA-1 and KAA-2, were elucidated by a combination of peptide mapping and complementary DNA (cDNA) cloning. They consisted of four internal tandem-repeated domains, which are conserved in high-mannose specific lectins from lower organisms, including a cyanobacterium Oscillatoria agardhii and a red alga Eucheuma serra. Using an Escherichia coli expression system, an active recombinant form of KAA-1 (His-tagged rKAA-1) was successfully generated in the yield of 115 mg per liter of culture. In a detailed oligosaccharide binding analysis by a centrifugal ultrafiltration-HPLC method with 27 pyridylaminated oligosaccharides, His-tagged rKAA-1 and rKAA-1 specifically bound to high-mannose N-glycans with an exposed α1-3 mannose in the D2 arm as the native lectin did. Predicted from oligosaccharide binding specificity, a surface plasmon resonance analysis revealed that the recombinants exhibit strong interaction with gp120, a heavily glycosylated envelope glycoprotein of HIV with high association constants (1.48 - 1.61 × 10(9) M(-1)). Native KAAs and the recombinants inhibited the HIV-1 entry at IC50s of low nanomolar levels (7.3-12.9 nM). Thus, the recombinant proteins would be useful as antiviral reagents targeting the viral surface glycoproteins with high-mannose N-glycans, and the cultivated alga K. alvarezii could also be a good source of not only carrageenans but also this functional lectin(s).
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, 739-8528, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Hirayama
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, 739-8528, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Shibata
authors.affiliation: Medical & Biological Laboratories Co., Ltd., 1063-103 Terasawaoka, Ina, Nagano, 396-0002, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Imamura
authors.affiliation: Department of Virology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Takemasa
authors.initials: T
authors.lastname: Sakaguchi
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, 739-8528, Japan. kanhori@hiroshima-u.ac.jp.
authors.forename: Kanji
authors.initials: K
authors.lastname: Hori
mesh_terms: D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D006678:HIV / Q000187:drug effects / Q000502:physiology*; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D037241:Mannose-Binding Lectins / Q000008:administration & dosage* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000378:metabolism; D000461:Rhodophyta / Q000235:genetics / Q000378:metabolism*; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D019380:Anti-HIV Agents; D015699:HIV Envelope Protein gp120; D037241:Mannose-Binding Lectins; D011994:Recombinant Proteins
keywords: Alga; Antiviral lectin; Carageenophyta; HIV; Kappaphycus alvarezii