The Structural Studies On Htra And Ppma From Streptococcus Pneumoniae

1. The structural study on High-temperature requirement protein A from Streptococcus pneumoniaeThe HtrA (high-temperature requirement A) protein is a heat shock protein and functions in a temperature-dependent manner as a molecular chaperone at normal temperature or as a serine protease at elevated temperature. This functional switch of HtrA plays an important role in controlling protein stability as well as degrading heat-denatured proteins to maintain cellular viability. HtrA is known as a key player in the protein quality control system in the bacterial periplasmic space. It was found that HtrA is essential for bacteria and cell survival at high temperature. Members of the HtrA family have been confirmed in many organisms, from Archaea to humans. Recent biochemical and structural analyses have suggested that both bacterial responses against a variety of stresses, and protein quality control, are subtly controlled by structural and functional changes occurring in the HtrA family proteins. However, the molecular mechanisms underlying protein quality control have yet to be definitively elucidated. In order to elucidate the roles of the HtrA family proteins, it will be required further biochemical and structure studies, which may further improve our understanding of the molecular functions performed by these proteins, as well as the mechanisms underlying their regulation. We got genomic DNA from streptococcus pneumoniae strain TRIG4, after PCR, the full-length and serine protease domain were obtained and inserted into p28 plasmid. Sufficient soluble HtrA full-lengh protein was produced after Ni-NTA affinity chromatography and gel-filtration chromatography. Despite the crystals have been obtained under many conditions, but none of them was suitable for X-ray diffraction. 2. The structural study on Potential proteinase maturation protein A from Streptococcus pneumoniaeA large body of physiological, cell biological, kinetic and structural data about peptidyl prolyl cis/trans isomerases (PPIases) has been accumulated during the past 20 years. Despite the simplicity of the catalyzed reaction, the enzymatic mechanism remains to be elucidated. Potential proteinase maturation protein A(PpmA)belongs to the parvulin PPIase family. We got genomic DNA from streptococcus pneumoniae strain TRIG4, after PCR, the full-length and the functional domain version of the ppmA gene were obtained and inserted into p28 plasmid. Sufficient soluble PpmA full-lengh protein was produced after Ni-NTA affinity chromatography and gel-filtration chromatography, but no crystal was obtained under the conditions employed.