title: Hagfish C1q: its unique binding property.
abstract: Hagfish C1q (HaC1q) was identified and characterized as a pattern-recognition molecule (PRM) in the hagfish complement system. The serum from hagfish, Eptatretus burgeri, was applied to a GlcNAc-agarose column and eluted sequentially with GlcNAc and EDTA. Four (31, 27, 26, and 19 kDa) and one (26 kDa) proteins were detected as bound molecules in the GlcNAc- and the EDTA-eluates, respectively. Among these, the 26 kDa protein from the EDTA eluate was found to be a homologue of mammalian C1q through cDNA analysis. HaC1q had an ability to bind to various microbes in a Ca(2+)-dependent manner and its target ligands on the microbes were lipopolysaccharide, lipoteichoic acid, and peptidoglycan. The binding of HaC1q to GlcNAc-agarose was not inhibited by an excess amount of monosaccharide such as GlcNAc. While HaC1q bound to Sepharose 6B with a matrix of GlcNAc-agarose (polymer of agarobiose), it did not bind to Sepharose 4B that contained lower concentration of agarobiose than Sepharose 6B. Therefore, the target of HaC1q on GlcNAc-agarose was concluded to be agarobiose and high density of the target moiety seemed to be required for the stable binding. This finding was in accordance with the known behavior of other lectins involved in the complement system. We have concluded that HaC1q recognizes agarobiose-like structures present on the surface of microbes and acts as a pattern-recognition molecule in the process for elimination of invading microbes.
authors.affiliation: Department of Biological Science, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Biological Science, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan. Electronic address: takamune@gpo.kumamoto-u.ac.jp.
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Takamune
authors.affiliation: Department of Applied Aquabiology, National Fisheries University, Shimonoseki, Yamaguchi 759-6595, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kondo
authors.affiliation: Department of Applied Aquabiology, National Fisheries University, Shimonoseki, Yamaguchi 759-6595, Japan.
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kato-Unoki
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Nakao
authors.affiliation: Department of Health Sciences, Faculty of Human Culture and Science, Prefectural University of Hiroshima, Ujina-Higashi, Hiroshima 734-8558, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Sano
authors.affiliation: Department of Health Sciences, Faculty of Human Culture and Science, Prefectural University of Hiroshima, Ujina-Higashi, Hiroshima 734-8558, Japan.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Fujii
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001424:Bacterial Infections / Q000276:immunology*; D002118:Calcium / Q000378:metabolism; D015922:Complement C1q / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004187:Disaccharides / Q000378:metabolism*; D006196:Hagfishes / Q000276:immunology*; D007113:Immunity, Innate; D008070:Lipopolysaccharides / Q000378:metabolism; D008322:Mammals; D008969:Molecular Sequence Data; D010457:Peptidoglycan / Q000378:metabolism; D011485:Protein Binding; D051192:Receptors, Pattern Recognition / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D013682:Teichoic Acids / Q000378:metabolism
chemical_list: D004187:Disaccharides; D008070:Lipopolysaccharides; D010457:Peptidoglycan; D051192:Receptors, Pattern Recognition; D013682:Teichoic Acids; C068544:neoagarobiose; C009900:lipoteichoic acid; D015922:Complement C1q; D002118:Calcium
keywords: C1q; Complement system; Eptatretus burgeri; Innate immunity; Pattern-recognition molecule