红霉素类药物在临床上应用广泛，我国是红霉素原料药的最大生产和出口国，但我国红霉素生产菌种的产率与国际先进水平还有很大差距。申请者已报道糖多孢红霉菌TetR家族中SACE_3986、SACE_7301、SACE_5754等许多调控因子（TFR），它们都与红霉素生物合成的产率相关。每个TFR都包含DNA结合结构域和配体结合结构域，而TFR结合配体不同直接影响靶基因的转录，甚至作用效果相反。本项目拟筛选至少10个TFR的配体，通过EMSA、qRT-PCR、gSELEX、转录组分析、BLI亲和力测定、蛋白质晶体学、体内配体阈值检测等技术，探讨红霉素生物合成相关TFR配体的结构特征、TFR-配体复合物空间结构、及其生物学功能等，进而分析配体介导红霉素生物合成相关TFR调控的分子机制。本项目为深入认识糖多孢红霉菌中红霉素生物合成的分子调控机制，及通过配体介导调控的手段提高红霉素产量奠定基础。

Erythromycin and its derivatives are widely used in clinic, China is the biggest producer and exporter of erythromycin bulk drugs, but there is still a large gap of productivity of erythromycin produced between China and advanced countries. Our group have reported several TetR family regulators (TFR) related to erythromycin yield in Saccharopolyspora erythraea, such as SACE_3986, SACE_7301, SACE_5754， and so on. Each TFR contains a DNA binding domain and a ligand binding domainn, and it may have different effects on the transcription of its target genes by binding different ligands, and even the opposite. In this proposal, we will screen ligands of at least 10 TFRs and explore their structural characteristics, crystal structures of TFR-ligand complexes, and biological functions by EMSA, qRT-PCR, gSELEX, transcriptome, BLI, protein crystallography and in vivo EGFP report system, and further analyze the molecular mechanism of regulation of ligand-mediated TFR for erythromycin synthesis. Our aim is to illustrate the regulatory molecular mechnism of erythromycin biosynthesis, and to increase erythromycin production by ligand-mediated pathways in S.erythraea.