Engineering biosynthesis and secretion of 1-alkenes in yeast

Engineering biosynthesis and secretion of 1-alkenes in yeas

植物源活性萜类化合物“细胞工厂”的构建及优化

植物源活性萜类化合物“细胞工厂”的构建及优

蛋白质组学和代谢组学在微生物代谢工程中的应用

构建微生物细胞工厂是化学品、生物能源以及药物分子可持续生产的可行性策略。然而,微生物的代谢复杂、调控严谨,制约着目标产物高效合成。蛋白质组学和代谢组学可以从系统生物学角度分析酶和代谢物组分,从而理解复杂的生物系统,为微生物代谢工程改造提供重要线索。该文介绍了蛋白质组学和代谢组学在微生物代谢工程中的应用,包括基因组尺度代谢模型构建、菌株生物合成优化、指导菌株耐受性改造、限速步骤预测、植物次级代谢途径挖掘,从而为微生物合成天然产物提供新的基因或途径。在此基础上,该文还展望了生物大数据未来的发展方向

蛋白质组学和代谢组学在微生物代谢工程中的应用

构建微生物细胞工厂是化学品、生物能源以及药物分子可持续生产的可行性策略。然而,微生物的代谢复杂、调控严谨,制约着目标产物高效合成。蛋白质组学和代谢组学可以从系统生物学角度分析酶和代谢物组分,从而理解复杂的生物系统,为微生物代谢工程改造提供重要线索。该文介绍了蛋白质组学和代谢组学在微生物代谢工程中的应用,包括基因组尺度代谢模型构建、菌株生物合成优化、指导菌株耐受性改造、限速步骤预测、植物次级代谢途径挖掘,从而为微生物合成天然产物提供新的基因或途径。在此基础上,该文还展望了生物大数据未来的发展方向

Construction of E. coli NAD+ auxotrophic strains and the biotechnological application thereof

NAD+ and its reduced form NADH are essential cofactors in biological systems. They function as cofactors in over 300 redox reactions in vivo1. The level of NAD+ and NADH is tightly controlled by a variety of mechanisms including their biosynthesis and salvage. Therefore, it is difficult to answer some fundamental questions such as the minimal NAD+ level for cell growth and the biological consequences of abnormal activity of a specific NAD+-dependent enzyme. We expressed the NTT4 gene from Chlamydiae UWE25 in Escherichia coli BW25113, as the NTT4 protein was reported as a NAD+ transporter that can specifically transport intact NAD+ across cytoplasmic membrane2. We knocked out the nadC gene responsible for de novo biosynthesis of NAD+ and constructed the strain E. coli BW25113 (ΔnadC, NTT4). It was found that NAD+ in the culture media could significantly promote the growth of BW25113 (ΔnadC, NTT4), suggesting that the NTT4 protein was functional in E. coli (Fig A, B). We then disrupted the other two genes, nadD and nadE, and obtained the strains E. coli BW25113 (ΔnadD, NTT4) and BW25113 (ΔnadE, NTT4). Cell growth of these two strains are depending on exogenous NAD+ supplemented in the media, suggesting that we have successfully engineered E. coli to hold an NAD+ auxotrophic phenotype. We are carrying out a number of experiments using these NAD+ auxotrophic strains to address some interesting questions which may not be able to do otherwise. Results will be discussed during the conference.NAD+ and its reduced form NADH are essential cofactors in biological systems. They function as cofactors in over 300 redox reactions in vivo1. The level of NAD+ and NADH is tightly controlled by a variety of mechanisms including their biosynthesis and salvage. Therefore, it is difficult to answer some fundamental questions such as the minimal NAD+ level for cell growth and the biological consequences of abnormal activity of a specific NAD+-dependent enzyme. We expressed the NTT4 gene from Chlamydiae UWE25 in Escherichia coli BW25113, as the NTT4 protein was reported as a NAD+ transporter that can specifically transport intact NAD+ across cytoplasmic membrane2. We knocked out the nadC gene responsible for de novo biosynthesis of NAD+ and constructed the strain E. coli BW25113 (ΔnadC, NTT4). It was found that NAD+ in the culture media could significantly promote the growth of BW25113 (ΔnadC, NTT4), suggesting that the NTT4 protein was functional in E. coli (Fig A, B). We then disrupted the other two genes, nadD and nadE, and obtained the strains E. coli BW25113 (ΔnadD, NTT4) and BW25113 (ΔnadE, NTT4). Cell growth of these two strains are depending on exogenous NAD+ supplemented in the media, suggesting that we have successfully engineered E. coli to hold an NAD+ auxotrophic phenotype. We are carrying out a number of experiments using these NAD+ auxotrophic strains to address some interesting questions which may not be able to do otherwise. Results will be discussed during the conference

利用人工氧还酶体系催化L-苹果酸氧化脱羧反应

利用含人工氧还酶体系的粗酶液代替纯酶催化反应,以省去酶分离纯化过程.由苹果酸酶突变体ME-t（MEL310R/Q401C）和非天然辅酶烟酰胺5-氟胞嘧啶二核苷酸（NFCD＋）组成的人工氧还酶体系可以催化氧化L-苹果酸生成丙酮酸,并得到非天然辅酶的还原态（NFCDH）.利用含人工氧还酶体系的粗酶液催化反应,只得到单一产物丙酮酸,其选择性与纯酶催化的相同.来自粪肠球菌Enterococcus faecalis的NADH氧化酶（NOX）可再生NFCD＋.与含NAD＋,ME粗酶液和NOX粗酶液的偶联反应体系相比,含NFCD＋,ME-t粗酶液和NOX粗酶液的体系获得的丙酮酸产率高9%,而副产物乳酸明显减少.可见人工氧还酶体系使用更方便,且产物选择性更高,有望代替纯酶催化反应.这为降低生物催化剂的成本,扩大生物催化反应的应用提供了一种新的策略

利用人工氧还酶体系催化L-苹果酸氧化脱羧反应

利用含人工氧还酶体系的粗酶液代替纯酶催化反应,以省去酶分离纯化过程.由苹果酸酶突变体ME-t（MEL310R/Q401C）和非天然辅酶烟酰胺5-氟胞嘧啶二核苷酸（NFCD＋）组成的人工氧还酶体系可以催化氧化L-苹果酸生成丙酮酸,并得到非天然辅酶的还原态（NFCDH）.利用含人工氧还酶体系的粗酶液催化反应,只得到单一产物丙酮酸,其选择性与纯酶催化的相同.来自粪肠球菌Enterococcus faecalis的NADH氧化酶（NOX）可再生NFCD＋.与含NAD＋,ME粗酶液和NOX粗酶液的偶联反应体系相比,含NFCD＋,ME-t粗酶液和NOX粗酶液的体系获得的丙酮酸产率高9%,而副产物乳酸明显减少.可见人工氧还酶体系使用更方便,且产物选择性更高,有望代替纯酶催化反应.这为降低生物催化剂的成本,扩大生物催化反应的应用提供了一种新的策略