The accD3 gene for mycolic acid biosynthesis as a target for improving fatty acid production by fatty acid-producing Corynebacterium glutamicum strains.
The accD3 gene for mycolic acid biosynthesis as a target for improving fatty acid production by fatty acid-producing Corynebacterium glutamicum strains.
复制标题
用于分枝酸生物合成的 accD3 基因作为提高产脂肪酸谷氨酸棒杆菌菌株脂肪酸产量的靶标。
DOI：
10.1007/s00253-018-9395-5
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Ikeda M
中科院分区：
文献类型：
--
作者：
Takeno S;Murata N;Kura M;Takasaki M;Hayashi M;Ikeda M
我们最近开发了谷氨酸棒杆菌菌株，由于增强了脂肪酸的生物合成，该菌株在培养上清液中产生游离脂肪酸。在这些生产菌株中，基本生产菌株PAS-15在脂肪酸生物合成阻遏蛋白基因中具有缺陷，高级生产菌株PCC-6具有两个额外的突变以增加菌株PAS-15的生产。本研究的目的是获得新的遗传性状，以提高这些生产者的脂肪酸生产。从PAS-15菌株中分离到一株新的产菌量增加的突变株，该突变株的accD 3基因发生错义突变（accD 3A 433 T），该突变株与C.谷氨酸，作为因果突变。经验证，突变accD 3A 433 T降低了AccD 3酶活性，并使菌株PAS-15的脂肪酸产量增加了1.8倍。PAS-15菌株accD 3A 433 T突变导致accD 3基因缺失，使脂肪酸产量提高了3.2倍。accD 3基因缺失和accD 3A 433 T突变使PAS-15菌株对万古霉素的敏感性显著增加，表明该工程削弱了分枝菌酸对细胞被膜的通透性屏障。此外，突变accD 3A 433 T还使菌株PCC-6的脂肪酸产量增加了1.3倍。这些增加的生产水平被认为不仅涉及从分枝菌酸生物合成到脂肪酸生产的碳通量的重定向，而且还涉及细胞被膜的渗透性。
We have recently developedCorynebacterium glutamicumstrains that produce free fatty acids in culture supernatant due to enhanced fatty acid biosynthesis. Of these producing strains, the basic producer PAS-15 has a defect in the gene for a fatty acid biosynthesis repressor protein, and the advanced producer PCC-6 has two additional mutations to augment the production by strain PAS-15. The aim of the present study was to obtain novel genetic traits for improving fatty acid production by these producers. A new mutant with increased production derived from strain PAS-15 had a missense mutation in theaccD3gene (mutationaccD3A433T), which is involved in the biosynthesis of mycolic acids that are cell envelope lipids ofC. glutamicum, as the causal mutation. MutationaccD3A433Twas verified to reduce the AccD3 enzymatic activity and increase fatty acid production in strain PAS-15 by 1.8-fold. Deletion of theaccD3gene in strain PAS-15, which was motivated by the characteristic of mutationaccD3A433T, increased fatty acid production by 3.2-fold. Susceptibility of strain PAS-15 to vancomycin was significantly increased byaccD3gene deletion and by mutationaccD3A433Tto the intermediate level, suggesting that the cell envelope permeability barrier by mycolic acids is weakened by this engineering. Furthermore, mutationaccD3A433Talso increased fatty acid production in strain PCC-6 by 1.3-fold. These increased production levels were suggested to be involved not only in the redirection of carbon flux from mycolic acid biosynthesis to fatty acid production but also in the permeability of the cell envelope.