Abstract
ParABS system plays a critical role in bacterial chromosome segregation to equipartition the newly replicated chromosomes into each daughter cell. ParABS system consists of ParA and ParB proteins, and one parS DNA sequence. In Helicobacter pylori, HpSoj, belonging to ParA superfamily, is an ATPase and binds chromosome DNA non-specifically. In previous studies, the ATPase hydrolysis activity of Soj could be promoted by the N-terminal domain of HpSpo0J, a member of ParB family. In this study, we determined the ATPase hydrolysis efficiency of each mole HpSoj as 2.73 mole Pi per hour and it was significantly stimulated approximately 3.5-fold by the N-terminal fragments HpSpo0JN50 (residues 1-50). Meanwhile, the dissociation constant (Kd) of the HpSoj-Spo0JN50 and HpSoj-Spo0JN110 (residues 1-110) complexes are 43 uM and 0.3 mM, respectively by Microscale thermophoresis experiments (MST). In addition, the crystal structure of the HpSoj-ATP complex was determined at 1.7Å in P212121 space group with unit cell parameters a = 48.33 Å, b = 94.01 Å, c = 112.74 Å. In the other hand, some microcrystals of the HpSoj-Spo0JN50 and HpSoj-Spo0JN110 complexes crystallization set up were appeared.