Responses to Reactive Oxygen Species in Escherichia Coli: The Roles of Aconitase a and Fur Protein

The Fur regulon is a well-characterized regulon that monitors intracellular iron concentrations by monitoring concentrations of the ferrous ion. We observed that sub-micromolar concentrations of H2O2 in vivo can cause E. coli catalase and NADH peroxidase mutants (Hpx -) to lose control of their intracellular iron pools. This concentration of H2O2 was sufficient to activate the fur regulon in vivo and cause induction of iron-import proteins. This would potentially result in an increased rate of H2O2-mediated Fenton damage. However, induction of fur expression by OxyR restored Fur repression in iron-replete media. Indeed, when the OxyR binding site upstream of fur was disrupted, Hpx- mutants accumulated high concentrations of intracellular free iron and suffered mutagenesis and bacteriostasis. These defects were eliminated by mutations or chelators that slowed iron import, confirming that dysregulation of iron uptake was the root problem. Collectively these data show the importance of controlling free iron levels intracellularly under oxidative stress.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Microbiology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Varghese, Shery Mathew

Contributors dc:contributor

• James Imlay

• Biology, Cell

Language dc:language

eng

Identifier

(MiAaPQ)AAI3290413

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/86700