Expression, Crystallization, And X-ray Diffraction Analysis Of Polyhydroxyalkanoate Granule Associated Proteins

Polyhydroxyalkanoates (PHA) are a wide range of macromolecular biopolyester synthesized in various microorganisms as intracellular carbon & energy storage materials under conditions of nutrient-imbalance with excess carbon source. Their chemical and physical properties depend on the monomeric compositions that are determined by the producing microorganism and their nutrition. PHA have been considered as alternatives for petrochemical-based plastics because they are biodegradable thermoplastics. PHA are also expected to become new tissue engineering materials due to their excellent biocompatibility properties. The expression of phaP_Ah & phaP_Re genes in Escherichia coli BL21 (DE3), affinity purification, and crystallization were achieved,respectively. Following results have been obtained in this study. Phasin PhaP_Ah from Aeromonas hydrophila strain 4AK4 was crystallized under the optimal condition using a hanging-drop vapour diffusion method. Single crystals were cryocooled for X-ray diffraction analysis. For the first time it was found that these phasin crystals belonged to the space group P2₁2₁2₁ with unit cell parameters a = 80.8A|°, b=108.9A|°, c=134.4A|°, α=β=γ=900. Crystal structure of the granule-associated protein phasin PhaP_Ah would be determined soon. Crystal improvement of the phasin PhaP_Re was still being in progress.