Biotechnology Core Laboratory, NIDDK, NIH, Bethesda, MD, USA.
N Biotechnol. 2013 Jan 25;30(2):269-73. doi: 10.1016/j.nbt.2011.11.007. Epub 2011 Nov 16.
When exposed to the nonmetabolized glucose derivative alpha methyl glucoside (αMG), both Escherichia coli K-12 (JM109 and MG1655) and E. coli B (BL21) respond by reducing the concentration of the mRNA of the ptsG gene which is responsible for the biosynthesis of the glucose transporter EIICB(glu). This occurs through the over-expression of the noncoding small RNA SgrS, which interacts specifically with the mRNA of the ptsG gene and prevents its translation. However, when these bacteria are exposed to a glucose concentration of 40 g/L, over-expression of SgrS is observed only in E. coli B (BL21). Unlike E. coli K-12 (JM109 and MG1655), which are affected by high glucose concentration and produce higher levels of acetate, E. coli B (BL21) is not affected. Based on this information, it was assumed that over-expression of SgrS enables E. coli B (BL21) to reduce its acetate excretion by controlling the glucose transport. When SgrS was over-expressed in both E. coli K-12 strains from a multicopy plasmid, it was possible to reduce their acetate excretion levels to those seen in E. coli B. This observation opens a new approach towards controlling bacterial metabolism through the use of noncoding RNA.
当暴露于未代谢的葡萄糖衍生物α-甲基葡萄糖苷（αMG）时，大肠杆菌 K-12（JM109 和 MG1655）和大肠杆菌 B（BL21）都会通过过度表达非编码小 RNA SgrS 来降低负责葡萄糖转运蛋白 EIICB(glu)生物合成的 ptsG 基因的 mRNA 浓度。这是通过 SgrS 与 ptsG 基因的 mRNA 特异性相互作用并阻止其翻译来实现的。然而，当这些细菌暴露于 40 g/L 的葡萄糖浓度时，仅在大肠杆菌 B（BL21）中观察到 SgrS 的过度表达。与受高葡萄糖浓度影响并产生更高水平乙酸盐的大肠杆菌 K-12（JM109 和 MG1655）不同，大肠杆菌 B（BL21）不受影响。基于此信息，假设 SgrS 的过度表达通过控制葡萄糖转运使大肠杆菌 B（BL21）能够减少其乙酸盐排泄。当 SgrS 在来自多拷贝质粒的两种大肠杆菌 K-12 菌株中过度表达时，能够将其乙酸盐排泄水平降低到大肠杆菌 B 中观察到的水平。这一观察结果为通过使用非编码 RNA 来控制细菌代谢开辟了一条新途径。
