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Stefan M. Gaida Mohab A. Al-Hinai Dinesh C. Indurthi Sergios A. Nicolaou Eleftherios T. Papoutsakis 《Nucleic acids research》2013,41(18):8726-8737
Synthetic acid tolerance, especially during active cell growth, is a desirable phenotype for many biotechnological applications. Natively, acid resistance in Escherichia coli is largely a stationary-phase phenotype attributable to mechanisms mostly under the control of the stationary-phase sigma factor RpoS. We show that simultaneous overexpression of noncoding small RNAs (sRNAs), DsrA, RprA and ArcZ, which are translational RpoS activators, increased acid tolerance (based on a low-pH survival assay) supra-additively up to 8500-fold during active cell growth, and provided protection against carboxylic acid and oxidative stress. Overexpression of rpoS without its regulatory 5′-UTR resulted in inferior acid tolerance. The supra-additive effect of overexpressing the three sRNAs results from the impact their expression has on RpoS-protein levels, and the beneficial perturbation of the interconnected RpoS and H-NS networks, thus leading to superior tolerance during active growth. Unlike the overexpression of proteins, overexpression of sRNAs imposes hardly any metabolic burden on cells, and constitutes a more effective strain engineering strategy. 相似文献
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Enhancement of the synthesis of RpoN, Cra, and H-NS by polyamines at the level of translation in Escherichia coli cultured with glucose and glutamate
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Terui Y Higashi K Taniguchi S Shigemasa A Nishimura K Yamamoto K Kashiwagi K Ishihama A Igarashi K 《Journal of bacteriology》2007,189(6):2359-2368
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Battesti A Tsegaye YM Packer DG Majdalani N Gottesman S 《Journal of bacteriology》2012,194(10):2470-2478
RpoS, the master sigma factor during stationary phase and under a variety of stress conditions, is regulated at multiple levels, including regulated degradation. Degradation is dependent upon ClpXP and the RssB adaptor protein. H-NS, a nucleoid-associated protein, affects the regulated degradation of RpoS; in the absence of H-NS, RpoS is stable. The mechanisms involved in this regulation were not known. We have found that H-NS inhibits the expression of iraD and iraM, the genes coding for two antiadaptor proteins that stabilize RpoS when overexpressed. The regulation by H-NS of iraM is independent from the previously demonstrated regulation by the PhoP/PhoQ two-component system. Moreover, differences in the behavior of several hns alleles are explained by a role for StpA, an H-NS-like protein, in the regulation of RpoS stability. This finding parallels recent observations for a role of StpA in regulation of RpoS stability in Salmonella. 相似文献