代谢工程方法改造大肠杆菌生产胸苷

Metabolic engineering of Escherichia coli for thymidine production

胸苷是抗艾滋病药物司他夫定(3′-脱氧-2′,3′-双脱氢胸苷)和叠氮胸苷的重要前体物质。应用代谢工程方法对大肠杆菌Escherichia coli BL21(DE3)生物合成胸苷进行了研究。通过敲除E.coli BL21嘧啶回补途径的deo A、tdk和udp三个基因,BS03工程菌株能够积累21.6 mg/L胸苷。为了增加合成胸苷前体物核糖-5-磷酸和NADPH的供给,进一步敲除pgi和pyr L使工程菌BS05胸苷的产量提高到90.5 mg/L。而通过过表达胸苷合成途径的ush A、thy A、dut、ndk、nrd A和nrd B六个基因,菌株BS08胸苷的产量能达到272 mg/L。通过分批补料发酵,BS08最终可以积累1 248.8 mg/L的胸苷。本研究结果表明经过代谢工程改造的E.coli BL21具有良好的胸苷合成能力和应用潜力。

Thymidine is a commercially useful precursor for production of antiviral compounds such as stavudine andazidothymidine. Biosynthesis of thymidine by Escherichia coli BL21 （DE3） was studied using metabolic engineering methods. The deoA, tdk and udp of the salvage pathway were disrupted from E. coli BL21 to construct BS03 that produced 21.6 mg thymidine per liter. Additional deletion of pgi and pyrL increased the supply of thymidine precursors and the resulting strain BS05 produced 90.5 mg thymidine/L. At last, ushA, thyA, dut, ndk, nrdA and nrdB ofthymidine biosynthetic pathway were overexpressed, and the resulting strain BS08 produced 272 mg thymidine/L. In fed-batch fermentation, BS08 accumulated 1 248.8 mg thymidine/L. Metabolically engineered strain E. coli has potential applications for thymidine production.