前期通过基因阻断发现Ste1与Ste2抑制链霉菌139胞外多糖依博素生物合成并获得ste1与ste2基因阻断株，随后检测上述菌株在不同培养条件下的氨基糖摄取，发现Ste1调节GlcNAc摄取，Ste2在GlcNAc和(GlcNAc)2摄取过程中发挥更为重要的作用；但Ste1、Ste2抑制依博素生物合成与调控氨基糖代谢的关联机制不明。基因组测序-代谢通路分析显示氨基糖可能调节链霉菌139中活化核苷酸单糖的生成，据此本项目拟在不同培养条件下检测链霉菌139、ste1和ste2基因阻断株的转录组信息，比较分析与氨基糖代谢及核苷酸单糖合成相关的差异表达基因，并通过凝胶阻滞分析Ste1和Ste2对上述基因的调控作用；通过基因阻断、蛋白表达等对相关基因进行体内外深入研究，阐明其与依博素生物合成的相关性。本研究将进一步揭示DasRABC调控胞外多糖生物合成的分子机制，具有重要的科学意义和应用价值。

In our previous research, we had obtained ste1 and ste2 mutant strains by gene disruption, and revealed Ste1 and Ste2 inhibit exopolysaccharide (Ebosin) biosynthesis as repressor. We also found Ste1 is involved in the uptake of N-acetylglucosamine (GlcNAc), and Ste2 plays a more important role for the uptake of GlcNAc and N,N´-Diacetylchitobiose ( (GlcNAc)2), especially for (GlcNAc)2. However, interplay between Ste1&Ste2 inhibiting exopolysaccharide biosynthesis and regulating aminosaccharide metabolism remains unclear. Aminosaccharide maybe involve in the biosynthesis of activated nucleotide-sugar in Streptomyces sp 139 through genome analysis. For illuminating the molecular mechanism of Ste1&Ste2 regulate exopolysaccharide biosynthesis and aminosaccharide metabolism in Streptomyces sp 139, we will identify differentially expressed genes (DEG) especially related to aminosaccharide metabolism and biosynthesis of activated nucleotide-sugar in Streptomyces sp 139, ste1 and ste2 mutant strains by high throughput transcriptome sequencing. We then confirm Ste1&Ste2-DEG interactions by EMSA (Electrophoretic Mobility Shift Assay). The key DEG involved in exopolysaccharide biosynthesis will be further characterized by gene disruption (in vivo) and protein expression (in vitro). This project will provide support to reveal molecular mechanism of exopolysaccharide biosynthesis regulated by DasRABC systems, and has important scientific significance and application value.