Allosteric regulation of the carbohydrate-binding ability of a novel conger eel galectin by D-mannoside.
Conger eel has two galectins, termed congerins I and II (Con I and II), that function in mucus as biodefense molecules. Con I and II have acquired a novel protein fold via domain swapping and a new ligand-binding site by accelerated evolution, which enables recognition of some marine bacteria. In this study, we identified a new congerin isotype, congerin P (Con-P), from the peritoneal cells of conger eel. Although Con-P displayed obvious homology with galectins, we observed substitution of 7 out of 8 amino acid residues in the carbohydrate recognition domain that are conserved in all other known galectins. To understand the structure-function relationships of this unique galectin, recombinant Con-P was successfully expressed in Escherichia coli by using a Con II-tagged fusion protein system and subsequently characterized. In the presence of D-mannose, Con-P displayed 30-fold greater hemagglutinating activity than Con I; however, no activity was observed without mannose, indicating that D-mannoside can act as a modulator of Con-P. Frontal affinity chromatography analysis showed that activated Con-P, allosterically induced by mannose, displayed affinity for oligomannose-type sugars as well as N-acetyllactosamine-type β-galactosides. Thus, Con-P represents a new member of the galectin family with unique properties.
Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan.
Mizuki
M
Watanabe
Osamu
O
Nakamura
Koji
K
Muramoto
Tomohisa
T
Ogawa
D000494:Allosteric Regulation / Q000187:drug effects / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D004524:Eels / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D037161:Galectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008362:Mannosides / Q000737:chemistry* / Q000494:pharmacology; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
D029941:Fish Proteins; D037161:Galectins; D008362:Mannosides; D011994:Recombinant Proteins