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

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 P65 with 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.

Source: Acta Crystallographica Section F - March 22, 2017 Category: Biochemistry Authors: Guo, L. Zhang, J. Cui, L. Liu, D. Ma, B. Wang, S. Li, H. Wu, Y. Liu, W. Tags: Helicobacter pylori adhesin A HpaA adhesion domain crystallization cations research communications Source Type: research