The sulfinic acid reductase, sulfiredoxin (Srx), was recently identified as the enzyme in yeast responsible for the reduction of the sulfinic acid moiety (Cys-SO2-) within several oxidatively-inactivated peroxiredoxins (Prxs). This discovery shattered the dogma of the irreversibility of overoxidation for the Prx enzyme family. Moreover, the ATP- and Mg2+-dependent repair or "retroreduction" of the overoxidized Prxs may modulate the role of these enzymes as regulators of hydrogen peroxide-mediated intracellular signaling. Based on the analysis of the in vivo oxidation state for a variety of human Prxs, repair of different Prx isoforms by Srx appears to proceed at different rates, in spite of their high overall degree of sequence identity. Our recent structure determinations of human Srx in complex with either phosphate or ADP have revealed a new protein fold and a novel nucleotide binding motif. Other preliminary data have confirmed some aspects of the proposed scheme for yeast Srx action, although several surprises in our results (the isolation of a disulfide-bonded rather than thiosulfinate-linked intermediate, and the reduction of the Srx:Prx complex by glutathione rather than thioredoxin) have suggested that further investigation is required. The goals of this proposal are: to determine the crystal structures of human Srx in complex with cofactors and human Prxs (Aim 1);and to carry out steady-state and partial turnover experiments coupled with site-directed mutagenesis to elucidate the nature and reaction rates of intermediates, and to characterize residues critical to catalysis (Aims 2 &3). These investigations will contribute significantly to our understanding of the molecular origins of sulfinic acid reductase action and the novel sulfur chemistry involved in this process.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM072866-05
Application #
7658744
Study Section
Macromolecular Structure and Function C Study Section (MSFC)
Program Officer
Anderson, Vernon
Project Start
2005-08-01
Project End
2011-02-28
Budget Start
2009-08-01
Budget End
2011-02-28
Support Year
5
Fiscal Year
2009
Total Cost
$238,112
Indirect Cost
Name
Wake Forest University Health Sciences
Department
Biochemistry
Type
Schools of Medicine
DUNS #
937727907
City
Winston-Salem
State
NC
Country
United States
Zip Code
27157
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Cunniff, Brian; Newick, Kheng; Nelson, Kimberly J et al. (2015) Disabling Mitochondrial Peroxide Metabolism via Combinatorial Targeting of Peroxiredoxin 3 as an Effective Therapeutic Approach for Malignant Mesothelioma. PLoS One 10:e0127310
Haynes, Alexina C; Qian, Jiang; Reisz, Julie A et al. (2013) Molecular basis for the resistance of human mitochondrial 2-Cys peroxiredoxin 3 to hyperoxidation. J Biol Chem 288:29714-23
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Jonsson, Thomas J; Johnson, Lynnette C; Lowther, W Todd (2009) Protein engineering of the quaternary sulfiredoxin.peroxiredoxin enzyme.substrate complex reveals the molecular basis for cysteine sulfinic acid phosphorylation. J Biol Chem 284:33305-10
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Jonsson, Thomas J; Murray, Michael S; Johnson, Lynnette C et al. (2008) Reduction of cysteine sulfinic acid in peroxiredoxin by sulfiredoxin proceeds directly through a sulfinic phosphoryl ester intermediate. J Biol Chem 283:23846-51
Jonsson, Thomas J; Tsang, Allen W; Lowther, W Todd et al. (2008) Identification of intact protein thiosulfinate intermediate in the reduction of cysteine sulfinic acid in peroxiredoxin by human sulfiredoxin. J Biol Chem 283:22890-4
Jonsson, Thomas J; Johnson, Lynnette C; Lowther, W Todd (2008) Structure of the sulphiredoxin-peroxiredoxin complex reveals an essential repair embrace. Nature 451:98-101
Jonsson, Thomas J; Lowther, W Todd (2007) The peroxiredoxin repair proteins. Subcell Biochem 44:115-41

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