(Deoxy)guanosine-5'-triphosphate (5'-(d)GTP), the precursor for synthesizing DNA or RNA in vivo, is an important raw material for various modern biotechnologies based on PCR. In this study, we investigated the application of whole-cell catalysts constructed by bacterial cell surface display in biosynthetic reactions of 5'-(d)GTP from (deoxy)guanosine-5'-monophosphate (5'-(d)GMP). By N-terminal or N- and C-terminal fusion of the ice nucleation protein, we successfully displayed the GMP kinase of Lactobacillus bulgaricus and the acetate kinase of E. coli on the surface of E. coli cells. A large amount of soluble target protein was obtained upon induction with 0.2 mM IPTG at 25 °C for 30 h. The conversion of dGMP was up to 91% when catalysed by the surface-displayed enzymes at 37 °C for 4 h. Up to 95% of the GMP was converted after 3 h of reaction. The stability of the whole-cell catalyst at 37 °C was very good. The enzyme activity was maintained above 50% after 9 rounds of recovery. Our research showed that only one-twentieth of the initial substrate concentration of added ATP was sufficient to meet the reaction requirements.

中文翻译：

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通过固定在大肠杆菌表面的 GMP 激酶和乙酸激酶生物合成（脱氧）鸟苷-5'-三磷酸

(Deoxy)guanosine-5'-triphosphate (5'-(d)GTP) 是体内合成 DNA 或 RNA 的前体，是各种基于 PCR 的现代生物技术的重要原料。在这项研究中，我们研究了由细菌细胞表面展示构建的全细胞催化剂在来自（脱氧）鸟苷-5'-单磷酸（5'-（d）GMP）的 5'-（d）GTP 的生物合成反应中的应用。通过冰核蛋白的N端或N端和C端融合，我们成功地在大肠杆菌细胞表面展示了保加利亚乳杆菌的GMP激酶和大肠杆菌的乙酸激酶。用 0.2 mM IPTG 在 25°C 下诱导 30 小时后获得大量可溶性靶蛋白。当表面展示酶在 37°C 下催化 4 小时时，dGMP 的转化率高达 91%。反应 3 小时后，高达 95% 的 GMP 被转化。全电池催化剂在37℃下的稳定性非常好。经过 9 轮恢复后，酶活仍保持在 50% 以上。我们的研究表明，添加 ATP 的初始底物浓度只有二十分之一就足以满足反应要求。