Vo Phuong N L, Lee Hyang-Mi, Ren Jun, Na Dokyun
Department of Biomedical Engineering, Chung-Ang University, Seoul, 06974, Republic of Korea.
J Biol Eng. 2021 Feb 18;15(1):7. doi: 10.1186/s13036-021-00260-x.
Escherichia coli is a widely used platform for metabolic engineering due to its fast growth and well-established engineering techniques. However, there has been a demand for faster-growing E. coli for higher production of desired substances. Here, to increase the growth of E. coli cells, we optimized the expression level of Hfq protein, which plays an essential role in stress responses. Six variants of the hfq gene with a different ribosome binding site sequence and thereby a different expression level were constructed. When the Hfq expression level was optimized in DH5α, its growth rate was increased by 12.1% and its cell density was also increased by 4.5%. RNA-seq and network analyses revealed the upregulation of stress response genes and metabolic genes, which increases the tolerance against pH changes. When the same strategy was applied to five other E. coli strains (BL21 (DE3), JM109, TOP10, W3110, and MG1655), all their growth rates were increased by 18-94% but not all their densities were increased (- 12 - + 32%). In conclusion, the Hfq expression optimization can increase cell growth rate and probably their cell densities as well. Since the hfq gene is highly conserved across bacterial species, the same strategy could be applied to other bacterial species to construct faster-growing strains.
由于生长迅速且工程技术成熟，大肠杆菌是代谢工程中广泛使用的平台。然而，人们一直需要生长更快的大肠杆菌以更高产量生产所需物质。在此，为了提高大肠杆菌细胞的生长速度，我们优化了Hfq蛋白的表达水平，该蛋白在应激反应中起关键作用。构建了六个具有不同核糖体结合位点序列从而具有不同表达水平的hfq基因变体。当在DH5α中优化Hfq表达水平时，其生长速率提高了12.1%，细胞密度也提高了4.5%。RNA测序和网络分析揭示了应激反应基因和代谢基因的上调，这增加了对pH变化的耐受性。当将相同策略应用于其他五种大肠杆菌菌株（BL21(DE3)、JM109、TOP10、W3110和MG1655）时，它们的生长速率均提高了18 - 94%，但并非所有菌株的细胞密度都增加了（-12 - +32%）。总之，Hfq表达优化可以提高细胞生长速率，可能也会提高细胞密度。由于hfq基因在细菌物种中高度保守，相同策略可应用于其他细菌物种以构建生长更快的菌株。
