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首页> 外文期刊>Applied Microbiology >Biosynthesis of l-Sorbose and l-Psicose Based on C—C Bond Formation Catalyzed by Aldolases in an Engineered Corynebacterium glutamicum Strain
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Biosynthesis of l-Sorbose and l-Psicose Based on C—C Bond Formation Catalyzed by Aldolases in an Engineered Corynebacterium glutamicum Strain

机译：谷氨酸棒杆菌菌株中醛缩酶催化CC键形成的L-山梨糖和L-蔗糖的生物合成

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The property of loose stereochemical control at aldol products from aldolases helped to synthesize multiple polyhydroxylated compounds with nonnatural stereoconfiguration. In this study, we discovered for the first time that some fructose 1,6-diphosphate aldolases (FruA) and tagatose 1,6-diphosphate (TagA) aldolases lost their strict stereoselectivity when using l-glyceraldehyde and synthesized not only l-sorbose but also a high proportion of l-psicose. Among the aldolases tested, TagA from Bacillus licheniformis (BGatY) showed the highest enzyme activity with l-glyceraldehyde. Subsequently, a “one-pot” reaction based on BGatY and fructose-1-phosphatase (YqaB) generated 378 mg/liter l-psicose and 199 mg/liter l-sorbose from dihydroxyacetone-phosphate (DHAP) and l-glyceraldehyde. Because of the high cost and instability of DHAP, a microbial fermentation strategy was used further to produce l-sorbose/l-psicose from glucose and l-glyceraldehyde, in which DHAP was obtained from glucose through the glycolytic pathway, and some recombination pathways based on FruA or TagA and YqaB were constructed in Escherichia coli and Corynebacterium glutamicum strains. After evaluation of different host cells and combinations of FruA or TagA with YqaB and optimization of gene expression, recombinant C. glutamicum strain WT(pXFTY) was selected and produced 2.53 g/liter total ketoses, with a yield of 0.50 g/g l-glyceraldehyde. Moreover, deletion of gene cgl0331 , encoding the Zn-dependent alcohol dehydrogenase in C. glutamicum , was confirmed for the first time to significantly decrease conversion of l-glyceraldehyde to glycerol and to increase yield of target products. Finally, fed-batch culture of strain SY14(pXFTY) produced 3.5 g/liter l-sorbose and 2.3 g/liter l-psicose, with a yield of 0.61 g/g l-glyceraldehyde. This microbial fermentation strategy also could be applied to efficiently synthesize other l-sugars.
机译：对醛缩酶醛缩酶产物的松散立体化学控制的性质有助于合成具有非天然立体构型的多种多羟基化合物。在这项研究中，我们首次发现某些果糖1,6-二磷酸醛缩酶（FruA）和塔格糖1,6-二磷酸（TagA）醛缩酶在使用l-甘油醛时不仅失去了严格的立体选择性，而且不仅合成了l-山梨糖而且左旋糖的比例也很高。在测试的醛缩酶中，地衣芽孢杆菌（BGatY）的TagA对1-甘油醛的酶活性最高。随后，基于BGatY和果糖-1-磷酸酶（YqaB）的“一锅法”反应从磷酸二羟基丙酮-磷酸酯（DHAP）和1-甘油醛生成了378 mg / L的L-山梨糖和199 mg / L的L-山梨糖。由于DHAP的成本高且不稳定，因此进一步采用微生物发酵策略从葡萄糖和L-甘油醛生产L-山梨糖/ L-癸糖，其中DHAP是通过糖酵解途径从葡萄糖中获得的，以及一些基于重组的途径在大肠杆菌和谷氨酸棒杆菌菌株中构建了FruA或TagA和YqaB的FacA。在评估了不同的宿主细胞以及FruA或TagA与YqaB的组合并优化了基因表达后，选择了重组谷氨酸棒杆菌WT（pXFTY），并生产了2.53 g /升的总酮糖，产量为0.50 g / g l-甘油醛。此外，首次证实在谷氨酸棒杆菌中编码锌依赖性醇脱氢酶的基因cg10333的缺失可显着降低1-甘油醛向甘油的转化并提高目标产物的产率。最后，菌株SY14（pXFTY）的分批补料培养产生了3.5g /升的l-山梨糖和2.3g /升的l-癸糖，产量为0.61g / g的l-甘油醛。这种微生物发酵策略也可以用于有效地合成其他L糖。

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