A C1 q domain containing protein from Crassostrea gigas serves as pattern recognition receptor and opsonin with high binding affinity to LPS

作者：Jiang, Shuai; Li, Hui; Zhang, Daoxiang; Zhang, Huan; Wang, Lingling; Sun, Jinsheng; Song, Linsheng^*

来源：Fish & Shellfish Immunology, 2015, 45(2): 583-591.

DOI：10.1016/j.fsi.2015.05.021

• Crassostrea gigas
• Innate immunity
• Liposaccharide
• CgC1qDC-1
• Phagocytosis

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 CgC1 qDC-1 gene was determined by performing a homologous search of eight tryptic peptides identified by IVIALDI-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 beta strands with a jelly-roll topology structure, which was similar to the structure of human gC1q domain. The mRNA transcripts of CgC1 qDC-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 (Kd = 0.09 x 10(-6) M). Moreover, CgC1qDC-1 significantly enhanced the phagocytosis of oyster hemocytes towards Gram-negative bacteria Escherichia con 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.

• 出版日期2015-8
• 单位中国科学院海洋研究所; 大连海洋大学