title: Crystallization and preliminary crystallographic studies of the complement 1qA globular domain from zebrafish, Dare-C1qAgD.
abstract: Complement 1q (C1q) is the first component of the complement system which can initiate the classical complement pathway. In human, C1q is composed of 18 polypeptide chains: six C1qA chains, six C1qB chains and six C1qC chains. Each chain has a signal peptide and is comprised of a collagen-like region and a C-terminal C1q globular domain (C1qgD), which is organized as a heterotrimer. C1qgD can recognize antigen-antibody complexes containing IgG and IgM or can bind directly to the C-reactive protein. Although the classical complement pathway is found from fish to mammals, only the human C1qgD structure has been determined. Compared with that of mammals, fish C1q exhibits similar immune functions and genome arrangement. In order to illustrate the structure of C1qgD in fish, zebrafish (Danio rerio) C1qA globular domain (Dare-C1qAgD) was expressed, purified and crystallized. X-ray diffraction data were collected from a crystal to a resolution of 2.05 Å; the crystal belonged to the orthorhombic space group P2₁2₁2₁, with unit-cell parameters a=50.347, b=85.059, c=95.560 Å. It contained three molecules in the asymmetric unit. The Matthews coefficient value VM was 2.31 Å3 Da(-1), with a calculated solvent content of 46.7%. The data will help to give insight into the structural basis of C1qA in fish species.
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing 100193, People's Republic of China.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing 100193, People's Republic of China.
authors.forename: Rong
authors.initials: R
authors.lastname: Chen
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing 100193, People's Republic of China.
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing 100193, People's Republic of China.
authors.forename: Mansoor
authors.initials: M
authors.lastname: Tariq
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing 100193, People's Republic of China.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Beijing 100193, People's Republic of China.
authors.forename: Chun
authors.initials: C
authors.lastname: Xia
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D015922:Complement C1q / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D008970:Molecular Weight; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D015027:Zebrafish / Q000276:immunology*; D029961:Zebrafish Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology
chemical_list: D021122:Protein Subunits; D011994:Recombinant Proteins; D029961:Zebrafish Proteins; D015922:Complement C1q
keywords: C1q globular domain; Danio rerio; complement 1q A chain; zebrafish