β- Hydroxyacyl-acyl Carrier Protein Dehydratase (FabZ) from Candidatus liberibacter asiaticum: Protein Characterization and Structural Modeling

β- Hydroxyacyl-acyl carrier protein (ACP) dehydratase (FabZ) is necessary for bacterial fatty acid biosynthesis. This protein catalyzes an essential step in the FASII pathway and in dehydration of β-hydrozyacyl-ACP to trans-2- acyl-ACP. Inhibition of β-hydroxyacyl-ACP dehydratase blocks the growth and reproduction of Candidatus liberibacter. β- Hydroxyacyl-ACP dehydratase is an attractive target for developing novel antimicrobials. In this study, the gene encoding enoyl-ACP dehydratase (FabZ) in C. liberibacter was cloned, expressed, and subjected to crystal structure analysis by X-ray diffraction. The optimum crystallization conditions were achieved with“Hampton research”pool of 2% v/v Tacsimate pH 5.0, 0.1 M sodium citrate tribasic dihydrate, pH 5.6, 16% w/v polyethylene glycol 3350 at 20oC, at a protein concentration of 7 mg/ mL. Small-angle X-ray scattering results showed that the ClFabZ protein was hexameric in solution. Crystal data were obtained using proteins produced in culture under the same conditions as those used for L-Se-Met-substituted ClFabZ. The crystal was in the space group of a lattice whose center was P6222, and the unit-cell parameters were a = b = 75.346 Å, c = 353.236 Å, a = β = 90°, and γ = 120°. These data were collected at a resolution of 2.9 Å. Furthermore, the interaction of hydrogen bonds and salt bridges in the ClFabZ structure were elucidated. Our results revealed the spatial structure information of FabZ in C. liberibacter asiaticum, which can serve as a basis for designing type-selective drugs by targeting FabZ.