{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/86700"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/86700","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Responses to Reactive Oxygen Species in Escherichia Coli: The Roles of Aconitase a and Fur Protein","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Varghese, Shery Mathew"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Microbiology","degree_department":null,"school":null,"contributors":["James Imlay"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-28T15:17:30Z","date_published":"2015-09-28T15:17:30Z","updated_at":"2026-07-22T22:26:27Z","subjects":["Biology, Cell"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(MiAaPQ)AAI3290413"],"render_values":[{"text":"(MiAaPQ)AAI3290413","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/86700","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["James Imlay"]},{"key":"dc:creator","label":"Author","values":["Varghese, Shery Mathew"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-09-28T15:17:30Z","10000-01-01","2007"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Microbiology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Biology, Cell"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/86700","(MiAaPQ)AAI3290413"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["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.","Made available in DSpace on 2015-09-28T15:17:30Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3290413.pdf: 3106804 bytes, checksum: 31dd5151371b37d8122fd5b15a69b0a7 (MD5) Previous issue date: 2007","Embargo set by: Seth Robbins for item 87981 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","132 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007."]},{"key":"dc:title","label":"Title","values":["Responses to Reactive Oxygen Species in Escherichia Coli: The Roles of Aconitase a and Fur Protein"]}]}],"canonical_facts":{"dc:contributor":["James Imlay"],"dc:creator":["Varghese, Shery Mathew"],"dc:date":["2015-09-28T15:17:30Z","10000-01-01","2007"],"dc:description":["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.","Made available in DSpace on 2015-09-28T15:17:30Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 3290413.pdf: 3106804 bytes, checksum: 31dd5151371b37d8122fd5b15a69b0a7 (MD5) Previous issue date: 2007","Embargo set by: Seth Robbins for item 87981 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","132 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007."],"dc:identifier":["http://hdl.handle.net/2142/86700","(MiAaPQ)AAI3290413"],"dc:language":["eng"],"dc:subject":["Biology, Cell"],"dc:title":["Responses to Reactive Oxygen Species in Escherichia Coli: The Roles of Aconitase a and Fur Protein"],"dc:type":["text"],"thesis:degree_discipline":["Microbiology"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:27Z"}