Xanthomonas campestris pv. campestris Hrp調控蛋白FhrR與人類先天免疫系統dsRNA受體蛋白DDX1-DDX21之複合體研究

The study contains two parts: the first part is determing the structure of protein XccFhrR, which regulates causative hrp genes, in Xanthomonas campestris pv. campestris (Xcc). FhrR transcription factor belongs to the TetR family, and regulates the expression of genes that encode flagella, Hrp and ribosomal proteins. We have obtained the native crystals of XccFhrR that diffracted to a resolution of 2.9 A. We tried to get the phase by the molecular replacement approach using the most similar protein Sco0520, but were not able to successfully extract the phase information. To solve the problem, we have prepared the Se-Met labeled protein. We have obtained preliminary Se-Met labeled crystals, but they are too small for X-ray diffrection. More efforts are required to grow bigger crystals. The second part is to study the complex structure of the dsRNA receptor protein DDX1 and DDX21 in the mammalian innate immune system. The full-lenth DDX1 and DDX21 are very difficult to obtain in soluble form, and we finally found the DDX11-440 and DDX211-571 fragements are very soluble. We have tried to obtain their co-crystal by using a variety of crystallization conditions, yet no crystal could be obtained so far.