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Colanic acid biosynthesis in Escherichia coli is dependent on lipopolysaccharide structure and glucose availability.
Microbiological Research ( IF 6.7 ) Pub Date : 2020-06-18 , DOI: 10.1016/j.micres.2020.126527
Chenhui Wang 1 , Hailing Zhang 2 , Jianli Wang 1 , Shanshan Chen 1 , Zhen Wang 1 , Lei Zhao 1 , Xiaoyuan Wang 3
Affiliation  

Lipopolysaccharide and colanic acid are important forms of exopolysaccharides located on the cell surface of Escherichia coli, but their interrelation with the cell stress response is not well understood. In this study, nine mutant strains with different structures of lipopolysaccharide were constructed from E. coli MG1655 by deletion of a single gene or multiple genes. All mutant strains did not produce colanic acid when grown in LB medium, but six of them could produce colanic acid when grown either in M9 medium in which glucose is the sole carbon source or in LB medium supplemented with glucose. The results indicate that colanic acid production in E. coli is dependent on both lipopolysaccharide structure and glucose availability. However, transcriptional analysis showed that 20 genes related to the colanic acid biosynthesis and the key gene rcsA in the Rcs system were all transcriptionally up-regulated in all of the nine mutant strains no matter they were grown in M9 or LB medium. This suggests that the availability of some nucleotide-sugar precursors shared by the biosynthesis of lipopolysaccharide and colanic acid might play a major role in colanic acid production in E. coli. Lipopolysaccharide pathway might have a huge priority to colanic acid pathway to use the common precursors; therefore, the colanic acid is not produced in MG1655 and the nine mutants when grown in LB medium. In the six mutant strains that can produce colanic acid in the glucose rich media, the common precursors might be abundant because they were not needed for synthesizing the mutant lipopolysaccharide.



中文翻译:

大肠杆菌中的钴酸的生物合成取决于脂多糖的结构和葡萄糖的利用率。

脂多糖和可乐酸是位于大肠杆菌细胞表面的胞外多糖的重要形式,但它们与细胞应激反应的相互关系尚不清楚。在这项研究中,通过删除单个基因或多个基因,从大肠杆菌MG1655构建了9个具有不同脂多糖结构的突变菌株。在LB培养基中生长时,所有突变株均不产生可乐酸,但其中六种在以葡萄糖为唯一碳源的M9培养基中或在补充葡萄糖的LB培养基中生长时均可以产生可乐酸。结果表明大肠杆菌中可乐酸的产生取决于脂多糖的结构和葡萄糖的利用率。然而,转录分析显示,在9种突变菌株中,无论它们在M9或LB培养基中生长,Rcs系统中20种与可乐酸生物合成相关的基因和关键基因rcsA均在转录上上调。这表明脂多糖和可乐酸的生物合成所共有的某些核苷酸糖前体的可用性可能在大肠杆菌中可乐酸的产生中起主要作用。脂多糖途径可能要优先于可乐酸途径才能使用常见的前体。因此,MG1655和LB培养基中生长的9个突变体中不产生可乐酸。在可以在富含葡萄糖的培养基中产生可乐酸的六种突变菌株中,常见的前体可能很丰富,因为合成突变型脂多糖不需要它们。

更新日期:2020-06-18
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