Structural Study Of The Polyamine Metabolism Related Proteins ODC&OAZ

Polyamines are important small molecules, which widely exist in living organisms. Polyamines play important roles in many important physiological functions including cell growth and differentiation and are also needed for the rapid growth of tumor cells. Ornithine decarboxylase (ornithine decarboxylase, ODC) is the first rate-limiting enzyme in the polyamine synthetic pathway. The expression of ODC is tightly regulated by feedback inhibition by its end products. ODC can also be degraded in conjunction with the protein antizyme (antizyme, OAZ). Both ODCand OAZ are involved in cell growth and differentiation, regulation gene expression, embryonic development, and other important physiological processes. They are also potential molecular targets for anti-tumor therapy. The crystal structure of ornithine decarboxylase from human and mouse has been determined. In this study, I cloned the ODC and OAZ genes from human and schizosaccharomyces and expressed them in E.coli:BL21(DE3). I have obtained stable, highly pure, homogeneous ODC-OAZ protein complex. Crystals in two different crystallization conditions were screened out at293K using sitting-drop vapor diffusion technique. I also cloned, expressed and purified the human OAZ-ORF2truction protein, which contains the ODC binding domain. By using the same method, I purified the ODC/OAZ-ORF2complexes and screened different crystallization conditions. Finally, I obtained crystals that diffracted to3A resolution using the synchrotron-radiation source. These structural studies are considerably useful for the further structural studies of the ODCand OAZ complex.