Abstract
Helicobacter pylori, a gram-negative spiral-shaped bacterium, can cause digestive illness to human and is recognized as the main cause of gastritis and peptic ulcer disease and gastric cancer. It has been shown to infect over 50% of the world’s population. The completed genome sequences of H. pylori strain 26695 have been reported by Tomb, J. F in 1997. Less information was known about hypothetical proteins in biological functions. The structures and functions of those hypothetical proteins could be studied by structural genomic approach. A system procedure of protein expression and purification was used to obtain the native proteins for structural genomic study. In this thesis, four of these selected proteins, HP0242, HP0035, HP0754 and Hp1160, were successfully purified and characterized by circular dichroism (CD), analytical ultracentrifuge (AU) and NMR analyses. Among these proteins, HP0242 had great 1H-15N HSQC but poor 3D-TOCSY. The crystal structure of HP0242 was found by X-ray diffraction (by Dr. Yuh-Ju Sun). The major structure of HP0242 is formed by a dimmer, and a dimer-dimer interaction forms a tetramer structure (a four-helix bundle). In order to identify the function of HP0242, the sequence analysis had been done. HP0242 gene is immediately down-stream of HP0243 gene (napA). The HP0243 and HP0242 were located in an operon which is involved in iron storage and Heme metabolism. Our result suggest that the function of HP0242 may be involved in iron metabolism.