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Open Access Highly Accessed Research article

Decrypting the H-NS-dependent regulatory cascade of acid stress resistance in Escherichia coli

Evelyne Krin1*, Antoine Danchin2 and Olga Soutourina34

Author Affiliations

1 Unité de Plasticité du Génome Bactérien, Institut Pasteur, France

2 AMAbiotics 5, rue Henri Desbruères, 91030 Evry Cedex, France

3 Unité des Bactéries Anaérobies et Toxines, Institut Pasteur, France

4 Université Paris 7-Denis Diderot, 75205 Paris, France

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BMC Microbiology 2010, 10:273  doi:10.1186/1471-2180-10-273

Published: 29 October 2010

Abstract

Background

H-NS regulates the acid stress resistance. The present study aimed to characterize the H-NS-dependent cascade governing the acid stress resistance pathways and to define the interplay between the different regulators.

Results

We combined mutational, phenotypic and gene expression analyses, to unravel the regulatory hierarchy in acid resistance involving H-NS, RcsB-P/GadE complex, HdfR, CadC, AdiY regulators, and DNA-binding assays to separate direct effects from indirect ones. RcsB-P/GadE regulatory complex, the general direct regulator of glutamate-, arginine- and lysine-dependent acid resistance pathways plays a central role in the regulatory cascade. However, H-NS also directly controls specific regulators of these pathways (e.g. cadC) and genes involved in general stress resistance (hdeAB, hdeD, dps, adiY). Finally, we found that in addition to H-NS and RcsB, a third regulator, HdfR, inversely controls glutamate-dependent acid resistance pathway and motility.

Conclusions

H-NS lies near the top of the hierarchy orchestrating acid response centred on RcsB-P/GadE regulatory complex, the general direct regulator of glutamate-, arginine- and lysine-dependent acid resistance pathways.