Caenorhabditis elegans galectins LEC-1–LEC-11: Structural features and sugar-binding properties

• Published in: Biochimica et biophysica acta Vol. 1780; no. 10; pp. 1131 - 1142
• Main Authors: Nemoto-Sasaki, Yoko, Hayama, Ko, Ohya, Hiroyuki, Arata, Yoichiro, Kaneko, Mika Kato, Saitou, Naruya, Hirabayashi, Jun, Kasai, Ken-ichi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2008
• Subjects: Alternative Splicing; Amino Acid Sequence; Amino Acid Substitution; Animals; Caenorhabditis elegans; Caenorhabditis elegans - genetics; Caenorhabditis elegans - metabolism; Carbohydrate Metabolism; Carbohydrate-binding property; Chromatography, Affinity; Cloning, Molecular; Conserved Sequence; DNA, Complementary; Frontal affinity chromatography; Galectin; Galectins - chemistry; Galectins - genetics; Galectins - isolation & purification; Galectins - metabolism; Genes, Helminth; Kinetics; Lectin; Molecular Sequence Data; Oligosaccharides - chemistry; Oligosaccharides - metabolism; Phylogeny; Protein Sorting Signals; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Alignment; Lectin; ORF; NA2, 3, and 4; L NFP-I, II, and III; FAC; Lac; Galectin; PA; Caenorhabditis elegans; Frontal affinity chromatography; CRD; LacNAc; L NT; Carbohydrate-binding property; LN2, 3, and 5; L NDFH; L NnT
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2008.07.003

Galectins form a large family of β-galactoside-binding proteins in metazoa and fungi. This report presents a comparative study of the functions of potential galectin genes found in the genome database of Caenorhabditis elegans. We isolated full-length cDNAs of eight potential galectin genes ( lec-2– 5 and 8– 11) from a λZAP cDNA library. Among them, lec-2–5 were found to encode 31–35-kDa polypeptides containing two carbohydrate-recognition domains similar to the previously characterized lec-1, whereas lec-8–11 were found to encode 16–27-kDa polypeptides containing a single carbohydrate-recognition domain and a C-terminal tail of unknown function. Recombinant proteins corresponding to lec-1–4, -6, and 8– 10 were expressed in Escherichia coli, and their sugar-binding properties were assessed. Analysis using affinity adsorbents with various β-galactosides, i.e., N-acetyllactosamine (Galβ1-4GlcNAc), lacto- N-neotetraose (Galβ1-4GlcNAcβ1-3Galβ1-4Glc), and asialofetuin, demonstrated that LEC-1–4, -6, and -10 have a significant affinity for β-galactosides, while the others have a relatively lower affinity. These results indicate that the integrity of key amino acid residues responsible for recognition of lactose (Galβ1-4Glc) or N-acetyllactosamine in vertebrate galectins is also required in C. elegans galectins. However, analysis of their fine oligosaccharide-binding properties by frontal affinity chromatography suggests their divergence towards more specialized functions.