title: Crystallization and X-ray analysis of the extracellular adhesion domain of Helicobacter pylori adhesin A: the significance of the cation composition in the crystallization precipitant.
abstract: Adherence to host cells is a crucial step in the process of bacterial infection, which is usually mediated by a number of outer membrane proteins identified as adhesins. Helicobacter pylori adhesin A (HpaA) is a member of the adhesin family that mediates the adherence of Helicobacter pylori to gastric epithelial cells, and consequently assists the bacteria in becoming a life-long colonizer of the human stomach. In this study, two constructs were made for the production of truncated HpaA proteins comprising residues 31-260 and 53-260, respectively. The products of both constructs were crystallized, but only the protein from the shorter construct (residues 53-260) formed crystals that were capable of diffraction. In the subsequent optimization trials, crystals in different forms were unexpectedly obtained by using lithium sulfate and ammonium sulfate as the precipitant. An X-ray data set was collected to 1.95 Å resolution on beamline BL18U1 at SSRF using a crystal grown with 1.92 M lithium sulfate, which belonged to space group P65with unit-cell parameters a = b = 95.42, c = 54.72 Å, γ = 120°, while another crystal grown with 1.9 M ammonium sulfate diffracted to 2.60 Å resolution and the collected data set was indexed in space group P21212, with unit-cell parameters a = 121.01, b = 190.56, c = 106.31 Å. The collection of diffraction data has established a solid basis for structure determination.
authors.affiliation: Institute of Immunology, The Third Military Medical University, Chongqing 400038, People's Republic of China.
authors.forename: Ling
authors.initials: L
authors.lastname: Guo
authors.affiliation: Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, The Third Military Medical University, Chongqing 400038, People's Republic of China.
authors.forename: Jinyong
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Institute of Immunology, The Third Military Medical University, Chongqing 400038, People's Republic of China.
authors.forename: Liwei
authors.initials: L
authors.lastname: Cui
authors.affiliation: Institute of Immunology, The Third Military Medical University, Chongqing 400038, People's Republic of China.
authors.forename: Dong
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Anatomy and Embryology, Medical Division, Peking University, Beijing 100191, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Ma
authors.affiliation: Institute of Immunology, The Third Military Medical University, Chongqing 400038, People's Republic of China.
authors.forename: Shufeng
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, The Third Military Medical University, Chongqing 400038, People's Republic of China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute of Immunology, The Third Military Medical University, Chongqing 400038, People's Republic of China.
authors.forename: Yuzhang
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Institute of Immunology, The Third Military Medical University, Chongqing 400038, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000645:Ammonium Sulfate / Q000737:chemistry; D002412:Cations; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005822:Genetic Vectors / Q000737:chemistry / Q000378:metabolism; D016480:Helicobacter pylori / Q000737:chemistry* / Q000378:metabolism; D018020:Lithium Compounds / Q000737:chemistry; D011487:Protein Conformation; D000072417:Protein Domains; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013431:Sulfates / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D018829:Adhesins, Bacterial; D002412:Cations; D018020:Lithium Compounds; D011993:Recombinant Fusion Proteins; D013431:Sulfates; C095977:adhesin A, Helicobacter; C054097:lithium sulfate; D000645:Ammonium Sulfate
keywords: Helicobacter pylori adhesin A; HpaA; adhesion domain; cations; crystallization