Human Intelectin Is a Novel Soluble Lectin That Recognizes Galactofuranose in Carbohydrate Chains of Bacterial Cell Wall

• Published in: The Journal of biological chemistry Vol. 276; no. 26; pp. 23456 - 23463
• Main Authors: Tsuji, Shoutaro, Uehori, Junji, Matsumoto, Misako, Suzuki, Yasuhiko, Matsuhisa, Akio, Toyoshima, Kumao, Seya, Tsukasa
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 29.06.2001; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Base Sequence; Blotting, Northern; Calcium - metabolism; Cell Wall - metabolism; Cloning, Molecular; Cytokines; Furans - metabolism; Galactans - metabolism; galactofuranose; Galactose - metabolism; GPI-Linked Proteins; Humans; intelectin; IntL gene; Lectins - chemistry; Lectins - genetics; Lectins - metabolism; Molecular Sequence Data; Polysaccharides, Bacterial - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; RNA, Messenger - biosynthesis; Sequence Homology, Amino Acid; Tissue Distribution
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M103162200

Galactofuranosyl residues are present in various microorganisms but not in mammals. In this study, we identified a human lectin binding to galactofuranosyl residues and named this protein human intelectin (hIntL). The mature hIntL was a secretory glycoprotein consisting of 295 amino acids and N-linked oligosaccharides, and its basic structural unit was a 120-kDa homotrimer in which 40-kDa polypeptides were bridged by disulfide bonds. The hIntL gene was split into 8 exons on chromosome 1q21.3, and hIntL mRNA was expressed in the heart, small intestine, colon, and thymus. hIntL showed high levels of homology with mouse intelectin,Xenopus laevis cortical granule lectin/oocyte lectin, lamprey serum lectin, and ascidian galactose-specific lectin. These homologues commonly contained no carbohydrate recognition domain, which is a characteristic of C-type lectins, although some of them have been reported as Ca2+-dependent lectins. Recombinant hIntL revealed affinities to d-pentoses and ad-galactofuranosyl residue in the presence of Ca2+, and recognized the bacterial arabinogalactan ofNocardia containing d-galactofuranosyl residues. These results suggested that hIntL is a new type lectin recognizing galactofuranose, and that hIntL plays a role in the recognition of bacteria-specific components in the host.AB036706