Involvement of the Global Regulator H-NS in the Survival of Escherichia coli in Stationary Phase

Chib, Savita and Mahadevan, Subramony (2012) Involvement of the Global Regulator H-NS in the Survival of Escherichia coli in Stationary Phase. In: JOURNAL OF BACTERIOLOGY, 194 (19). pp. 5285-5293.

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Abstract

Long-term batch cultures of Escherichia coli grown in nutrient-rich medium accumulate mutations that provide a growth advantage in the stationary phase (GASP). We have examined the survivors of prolonged stationary phase to identify loci involved in conferring a growth advantage and show that a mutation in the hns gene causing reduced activity of the global regulator H-NS confers a GASP phenotype under specific conditions. The hns-66 allele bears a point mutation within the termination codon of the H-NS open reading frame, resulting in a longer protein that is partially functional. Although isolated from a long-term stationary-phase culture of the parent carrying the rpoS819 allele that results in reduced RpoS activity, the hns-66 survivor showed a growth disadvantage in the early stationary phase (24 to 48 h) when competed against the parent. The hns-66 mutant is also unstable and reverts at a high frequency in the early stationary phase by accumulating second-site suppressor mutations within the ssrA gene involved in targeting aberrant proteins for proteolysis. The mutant was more stable and showed a moderate growth advantage in combination with the rpoS819 allele when competed against a 21-day-old parent. These studies show that H-NS is a target for mutations conferring fitness gain that depends on the genetic background as well as on the stage of the stationary phase.

Item Type:	Journal Article
Publication:	JOURNAL OF BACTERIOLOGY
Publisher:	AMER SOC MICROBIOLOGY
Additional Information:	Copyright for this article belongs to AMER SOC MICROBIOLOGY
Department/Centre:	Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	10 Dec 2012 09:29
Last Modified:	11 Dec 2012 06:00
URI:	http://eprints.iisc.ac.in/id/eprint/45228

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