Optimized expression of Hfq protein increases Escherichia coli growth by
enhancing acid resistance
Abstract
Escherichia coli is a widely used platform for metabolic engineering,
for 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, we optimized Hfq protein expression, which
plays an essential role in stress response, to increase stress tolerance
by designing the ribosome binding site of the hfq gene thereby
increasing cell growth. As a result, Hfq expression correlated with
growth rate, and its optimal expression increased the maximal optical
density in the stationary phase by 30.9% relative to that in the
wild-type E. coli. RNA-seq and network analyses revealed the
upregulation of stress response genes specifically that of the gadE
gene, a transcription factor involved in acid resistance. The optimized
gadE expression also increased the optical density of E. coli by 22.8%,
while co-expression of hfq and gadE genes increased growth by up to
29.7%. In conclusion, our optimized Hfq increased E. coli optical
density by improving cellular stress response, specifically acid
tolerance. The fast-growing E. coli constructed in this study would be a
useful metabolic engineering platform for the production of proteins and
other desired substances.