A Caenorhabditis elegans glycolipid-binding galectin functions in host defense against bacterial infection.
Galectins are a family of beta-galactoside-binding proteins that are widely found among animal species and that regulate diverse biological phenomena. To study the biological function of glycolipid-binding galectins, we purified recombinant Caenorhabditis elegans galectins (LEC-1-11) and studied their binding to C. elegans glycolipids. We found that LEC-8 binds to glycolipids in C. elegans through carbohydrate recognition. It has been reported that Cry5B-producing Bacillus thuringiensis strains can infect C. elegans and that the C. elegans Cry5B receptor molecules are glycolipids. We found that Cry5B and LEC-8 bound to C. elegans glycolipid-coated plates in a dose-dependent manner and that Cry5B binding to glycolipids was inhibited by the addition of LEC-8. LEC-8 is usually expressed strongly in the pharyngeal-intestinal valve and intestinal-rectal valve and is expressed weakly in intestine. However, when C. elegans were fed Escherichia coli expressing Cry5B, intestinal LEC-8::EGFP protein levels increased markedly. In contrast, LEC-8::EGFP expression triggered by Cry5B was reduced in toxin-resistant C. elegans mutants, which had mutations in genes involved in biosynthesis of glycolipids. Moreover, the LEC-8-deficient mutant was more susceptible to Cry5B than wild-type worms. These results suggest that the glycolipid-binding lectin LEC-8 contributes to host defense against bacterial infection by competitive binding to target glycolipid molecules.
Ideo
Hiroko
H
Innovative Research Initiatives, Tokyo Institute of Technology, Yokohama 226-8503, USA.
Fukushima
Keiko
K
Gengyo-Ando
Keiko
K
Mitani
Shohei
S
Dejima
Katsufumi
K
Nomura
Kazuya
K
Yamashita
Katsuko
K
D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism / Q000502:physiology; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism / Q000633:toxicity; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D029742:Caenorhabditis elegans Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004731:Endotoxins / Q000378:metabolism / Q000633:toxicity; D004797:Enzyme-Linked Immunosorbent Assay; D037161:Galectins / Q000235:genetics / Q000378:metabolism*; D006017:Glycolipids / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006460:Hemolysin Proteins / Q000378:metabolism / Q000633:toxicity; D054884:Host-Pathogen Interactions; D007413:Intestinal Mucosa / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D029742:Caenorhabditis elegans Proteins; D004731:Endotoxins; D037161:Galectins; D006017:Glycolipids; D006460:Hemolysin Proteins; C544606:LEC-8 protein, C elegans; D020033:Protein Isoforms; D011994:Recombinant Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D049452:Green Fluorescent Proteins