The Structural Biological Research Of Virulence Regulator SarV,SarX And RNase J1/J2from Staphylococcus Aureus

Infection of bacteria is an important cause of human disease.But with the wide use of antibiotics, drug resistancesare more and more serious. Staphylococcus aureus is an opportunistic pathogen which widely exists in the hospitals and community. S. aureus can cause food poisoning, pneumonia, meningitis, endocarditis, toxic shock syndrome and other serious diseases. Because of its resistances to almost all antibiotics including vancomycin, infection and mortality rate of S. aureusare high, which has been a serious problem of human health.Infection of S. aureus normally from the wound spreads to the blood, and different tissues of the host. After entering tissues, S. aureus produces a large number of virulence factors, including cell wall proteins, enzymes, toxins, polysaccharide and gene products of tissue localization, tissue damage and immune evasion. The expression of the virulence genes is controlled by regulation system, such as the two-component regulatory system (agr, saeRS, srrAB, arlRS) and the global transcriptional regulatory system (sarA, sigB, sarA homologue, tcaRA etc.). SarV and SarX are the member of global transcriptional regulation system, which is important for the infection and virulence regulation. Detemination of the crystal structures of SarX and SarV complexed with DNA will help us to further understand the mechanism of virulence factors regulation, which mayprovide clues for the development of antibacterial drugs.The degradation of RNA need to be controlled strictly to ensure the degradation process is orderly and coordinated. Although the RNA degradosome is not conservative in composition and they have no common evolutionary ancestor, degradosome can be found in almost all different bacterial. This implies that the RNA degradosome plays an important role in the RNA metabolic processes of bacteria. RNA degradosome of S. aureus contains enolase, pfkA, PNPase, RNase J1, RNase J2, RNase Y and CshA. The degradation of RNA mainly depends on RNase J1, RNase J2. Although the degradation progress of RNA has been studied substantially, but the mechanism for RNA degradosome assembly and the interactions between each member are not clear. Solve the structures of RNase J1and J2will reveal the roles they played in RNA degradosome.SarX and SarV were expressed, purified and the crystallization conditions were screened.The X-ray diffraction data of native SarV protein and selenium labled SarX were collected. The structure of SarX was solved. RNase J1and J2were expressed and purified. Crystal screen were performed and crystals were observed in many conditions.The X-ray diffraction data were collected to3.7A.We verified the interaction between RNase J1and J2.Interaction of RNase J1with PNPase, CshA have also been detected.