Differential structure and activity between human and mouse intelectin-1: human intelectin-1 is a disulfide-linked trimer, whereas mouse homologue is a monomer.
Human intelectin-1 (hITLN-1) is a 120-kDa lectin recognizing galactofuranosyl residues found in cell walls of various microorganisms but not in mammalian tissues. Although mouse intelectin-1 (mITLN-1) has been identified previously, its biochemical properties and functional characteristics have not been studied. Therefore, we have compared structures and saccharide-binding specificities of hITLN-1 and mITLN-1 using recombinant proteins produced by mammalian cells. Recombinant hITLN-1 is a trimer, disulfide-linked through Cys-31 and Cys-48, and N-glycosylated at Asn-163. Despite 84.9% amino acid identity to hITLN-1, recombinant and intestinal mITLN-1 are unglycosylated 30-kDa monomers. Recombinant hITLN-1, as well as recombinant and intestinal mITLN-1 were purified by Ca(2+)-dependent adsorption to galactose-Sepharose. In competitive binding studies, hITLN-1 was eluted from galactose-Sepharose by 100 mM 2-deoxygalactose, a galactofuranosyl disaccharide, d-xylose, and both d- and l-ribose. In contrast, mITLN-1 was partially eluted by the galactofuranosyl disaccharide, and only minimally by the other saccharides indicating that the two intelectins have different saccharide-binding specificities. When the N- and C-terminal regions of hITLN-1 were replaced, respectively, with those of mITLN-1, galactose-Sepharose binding was associated with the C-terminal regions. Finally, hITLN-1 binding to galactose-Sepharose was not affected by the substitution of the Cys residues in the N-terminal region that are necessary for oligomer formation, nor was it affected by the removal of the N-linked oligosaccharide at Asn-163. Although both hITLN-1 and mITLN-1 recognize galactofuranosyl residues, our comparative studies, taken together, demonstrate that these intelectins have different quaternary structures and saccharide-binding specificities.
Tsuji
Shoutaro
S
Biomedical Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA. stsuji@gancen.asahi.yokohama.jp
Yamashita
Makiko
M
Nishiyama
Akihito
A
Shinohara
Tsutomu
T
Li
Zhongwei
Z
Myrvik
Quentin N
QN
Hoffman
Donald R
DR
Henriksen
Ruth Ann
RA
Shibata
Yoshimi
Y
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D016207:Cytokines / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D005260:Female; D058851:GPI-Linked Proteins; D005690:Galactose / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007413:Intestinal Mucosa / Q000378:metabolism; D037102:Lectins / Q000737:chemistry*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D011817:Rabbits; D011994:Recombinant Proteins / Q000378:metabolism; D012685:Sepharose / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D016207:Cytokines; D004220:Disulfides; D058851:GPI-Linked Proteins; C432397:ITLN1 protein, human; D007074:Immunoglobulin G; C115657:Itlnb protein, mouse; D037102:Lectins; D011994:Recombinant Proteins; D012685:Sepharose; D005690:Galactose