Enhancing the atom economy of polyketide biosynthetic processes through metabolic engineering
Enhancing the atom economy of polyketide biosynthetic processes through metabolic engineering
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DOI：
10.1021/bp010045j
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发表时间：
2001-07-01
影响因子：
2.9
通讯作者：
Khosla, C
中科院分区：
文献类型：
--
作者：
Lombó, F;Pfeifer, B;Khosla, C
聚酮化合物是一类具有生物活性的天然产物，由衍生自α-羧基化辅酶A硫酯如丙二酰辅酶A和（2S）-甲基丙二酰辅酶A的结构单元合成。聚酮化合物发酵过程在天然和异源宿主中的生产率经常受到这些前体在体内的可用性的限制。我们描述了一种代谢工程策略，以提高聚酮生物合成的产量和体积生产率。来自三叶根瘤菌的基因matB和matC分别编码丙二酰辅酶A合成酶和推定的二羧酸转运蛋白。这些蛋白质可以直接将外源丙二酸和甲基丙二酸转化为它们相应的CoA硫酯，每产生1摩尔酰基-CoA需要2摩尔ATP。matBC在产生大环内酯6-脱氧阿糖胞苷B的天蓝色链霉菌重组菌株中的异源表达导致大环内酯滴度增加300%。添加到发酵培养基中的甲基丙二酸酯单元的大约三分之一转化为大环内酯，这一事实说明了生物转化的不寻常的效率。将廉价的原料如丙二酸酯和甲基丙二酸酯直接转化为聚酮化合物代表了获得这些高价值天然产物的最具碳效率和能源效率的途径，并且对许多商业和开发阶段小分子的成本效益发酵具有影响。
Polyketides, a large family of bioactive natural products, are synthesized from building blocks derived from a-carboxylated Coenzyme A thioesters such as malonyl-CoA and (2S)-methylmalonyl-CoA. The productivity of polyketide fermentation processes in natural and heterologous hosts is frequently limited by the availability of these precursors in vivo. We describe a metabolic engineering strategy to enhance both the yield and volumetric productivity of polyketide biosynthesis. The genes matB and matC from Rhizobium trifolii encode a malonyl-CoA synthetase and a putative dicarboxylate transport protein, respectively. These proteins can directly convert exogenous malonate and methylmalonate into their corresponding CoA thioesters with an ATP requirement of 2 mol per mol of acyl-CoA produced. Heterologous expression of matBC in a recombinant strain of Streptomyces coelicolor that produces the macrolactone 6-deoxyerythronolide B results in a 300% enhancement of macrolactone titers. The unusual efficiency of the bioconversion is illustrated by the fact that approximately one-third of the methylmalonate units added to the fermentation medium are converted into macrolactones. The direct conversion of inexpensive feedstocks such as malonate and methylmalonate into polyketides represents the most carbon- and energy-efficient route to these high value natural products and has implications for cost-effective fermentation of numerous commercial and development-stage small molecules.