The goal of this project is to determine the mechanism(s) and physiological impact of endogenous superoxide production in Escherichia coli. Strains that lack superoxide dismutase exhibit severe aerobic growth deficiencies, indicating that superoxide is made intracellularly during aerobiosis. Our studies have indicated that superoxide is formed primarily by autoxidation of components of the respiratory chain, including fumarate reductase. We now propose: (1) to identify the other sites of respiratory superoxide production; (2) to determine how the electronic structure of fumarate reductase singularly predisposes it to generate superoxide; (3) to establish whether the superoxide flux from respiratory sources is large enough to damage SOD-proficient cells; and (4) to determine whether superoxide production by low-potential anaerobic respiratory chains causes acute oxidative stress when this facultative anaerobe enters an aerobic environment. For years workers have imposed artificial stresses upon E. coli in order to characterize its elaborate network of oxidative defenses. We want to identify the endogenous sources of the oxidants against which E. coli has evolved to defend itself. More generally, this investigation will identify the characteristics that predispose electron carriers to generate superoxide. Such information may assist in identifying similar sources of superoxide in mammalian cells. Recent work indicates that endogenous superoxide causes the familial form of the neurological disorder amyotrophic lateral sclerosis. Circumstantial evidence has suggested that superoxide may also have a role in the initiation or progression of other clinical disorders, including heart disease and cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM049640-02
Application #
2187163
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1994-05-01
Project End
1999-04-30
Budget Start
1995-05-01
Budget End
1996-04-30
Support Year
2
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Illinois Urbana-Champaign
Department
Microbiology/Immun/Virology
Type
Schools of Arts and Sciences
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
Lu, Zheng; Sethu, Ramakrishnan; Imlay, James A (2018) Endogenous superoxide is a key effector of the oxygen sensitivity of a model obligate anaerobe. Proc Natl Acad Sci U S A 115:E3266-E3275
Li, Xin; Imlay, James A (2018) Improved measurements of scant hydrogen peroxide enable experiments that define its threshold of toxicity for Escherichia coli. Free Radic Biol Med 120:217-227
Khademian, Maryam; Imlay, James A (2017) Escherichia coli cytochrome c peroxidase is a respiratory oxidase that enables the use of hydrogen peroxide as a terminal electron acceptor. Proc Natl Acad Sci U S A 114:E6922-E6931
Lu, Zheng; Imlay, James A (2017) The Fumarate Reductase of Bacteroides thetaiotaomicron, unlike That of Escherichia coli, Is Configured so that It Does Not Generate Reactive Oxygen Species. MBio 8:
Imlay, James A (2015) Transcription Factors That Defend Bacteria Against Reactive Oxygen Species. Annu Rev Microbiol 69:93-108
Mancini, Stefano; Imlay, James A (2015) Bacterial Porphyrin Extraction and Quantification by LC/MS/MS Analysis. Bio Protoc 5:
Mancini, Stefano; Imlay, James A (2015) The induction of two biosynthetic enzymes helps Escherichia coli sustain heme synthesis and activate catalase during hydrogen peroxide stress. Mol Microbiol 96:744-63
Imlay, James A (2015) Diagnosing oxidative stress in bacteria: not as easy as you might think. Curr Opin Microbiol 24:124-31
Imlay, James A (2014) The mismetallation of enzymes during oxidative stress. J Biol Chem 289:28121-8
Sobota, Jason M; Gu, Mianzhi; Imlay, James A (2014) Intracellular hydrogen peroxide and superoxide poison 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase, the first committed enzyme in the aromatic biosynthetic pathway of Escherichia coli. J Bacteriol 196:1980-91

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