title: Purification, crystallization and X-ray crystallographic analysis of a putative exopolyphosphatase from Zymomonas mobilis.
abstract: Exopolyphosphatase (PPX) enzymes degrade inorganic polyphosphate (poly-P), which is essential for the survival of microbial cells in response to external stresses. In this study, a putative exopolyphosphatase from Zymomonas mobilis (ZmPPX) was crystallized. Crystals of the wild-type enzyme diffracted to 3.3 Å resolution and could not be optimized further. The truncation of 29 amino acids from the N-terminus resulted in crystals that diffracted to 1.8 Å resolution. The crystals belonged to space group C2, with unit-cell parameters a = 122.0, b = 47.1, c = 89.5 Å, α = γ = 90, β = 124.5°. An active-site mutant that crystallized in the same space group and with similar unit-cell parameters diffracted to 1.56 Å resolution. One molecule was identified per asymmetric unit. Analytical ultracentrifugation confirmed that ZmPPX forms a dimer in solution. It was confirmed that ZmPPX possesses exopolyphosphatase activity against a synthetic poly-P substrate.
authors.affiliation: College of Life Sciences, Nankai University, People's Republic of China.
authors.forename: Aili
authors.initials: A
authors.lastname: Zhang
authors.affiliation: College of Life Sciences, Nankai University, People's Republic of China.
authors.forename: Erhong
authors.initials: E
authors.lastname: Guo
authors.affiliation: College of Life Sciences, Nankai University, People's Republic of China.
authors.forename: Lanfang
authors.initials: L
authors.lastname: Qian
authors.affiliation: Faculty of Dentistry, University of Hong Kong, Hong Kong.
authors.forename: Nga-Yeung
authors.initials: NY
authors.lastname: Tang
authors.affiliation: Faculty of Dentistry, University of Hong Kong, Hong Kong.
authors.forename: Rory M
authors.initials: RM
authors.lastname: Watt
authors.affiliation: College of Life Sciences, Nankai University, People's Republic of China.
authors.forename: Mark
authors.initials: M
authors.lastname: Bartlam
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000737:chemistry* / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002850:Chromatography, Gel; D003460:Crystallization; D018360:Crystallography, X-Ray; D014461:Ultracentrifugation; D017355:Zymomonas / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D017766:Acid Anhydride Hydrolases; C020137:exopolyphosphatase
keywords: PPX/GppA family; Zymomonas mobilis; crystallization; exopolyphosphatase