A C1q domain containing protein from Crassostrea gigas serves as pattern recognition receptor and opsonin with high binding affinity to LPS. Issue 2 (August 2015)

• Record Type: Journal Article
• Authors: Jiang, Shuai; Li, Hui; Zhang, Daoxiang; Zhang, Huan; Wang, Lingling; Sun, Jinsheng; Song, Linsheng
• Is Part Of: Fish & shellfish immunology. Volume 45:Issue 2(2015:Aug.)
• Page Start: 583
• Page End: 591
• Publication Date: 2015-08
• Subjects: Crassostrea gigas -- Innate immunity -- Liposaccharide -- CgC1qDC-1 -- Phagocytosis; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2015.05.021
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: C1q proteins serve as pattern recognition receptors and involve in the pathogen recognition and complement pathway activation. In the present study, a novel C1q domain containing protein from Crassostrea gigas (designated CgC1qDC-1) was isolated by liposaccharide-Sepharose 6B affinity chromatography. The coding sequence of CgC1qDC-1 gene was determined by performing a homologous search of eight tryptic peptides identified by MALDI-TOF/TOF-MS against the genome of C. gigas . The coding sequence of CgC1qDC-1 was of 387 bp encoding a polypeptide of 128 amino acids containing a typical globular C1q domain. The globular C1q domain possessed eight β strands with a jelly-roll topology structure, which was similar to the structure of human gC1q domain. The mRNA transcripts of CgC1qDC-1 were dominantly expressed in mantle and hemocytes, while low expressed in hepatopancreas, gonad, gill and muscle. The expression level of CgC1qDC-1 increased drastically at 6 h after Vibrio splendidus stimulation, and then gradually fell to the normal level at about 24 h. ELISA assay quantified that CgC1qDC-1 bound to LPS with high binding affinity ( K d = 0.09 × 10 −6 M). Moreover, CgC1qDC-1 significantly enhanced the phagocytosis of oyster hemocytes towards Gram-negative bacteria Escherichia coli and V . splendidus . These results collectively indicated that CgC1qDC-1 could serve as pattern recognition receptor and opsonin in the innate immune response against invading Gram-negative bacteria. Highlights: A novel C1qDC protein was isolated from Crassostrea gigas by affinity chromatography. CgC1qDC-1 acted as pattern recognition receptor with high binding affinity to LPS. CgC1qDC-1 mRNA levels significantly increased after V. splendidus stimulation. CgC1qDC-1 protein drastically enhanced the phagocytosis of oyster hemocytes.