Journal
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
Volume 1837, Issue 12, Pages 1932-1943Publisher
ELSEVIER
DOI: 10.1016/j.bbabio.2014.08.007
Keywords
Reactive oxygen species; Oxidative stress; Alkylhydroperoxide reductase; Redox homeostasis; Structural biology; Electron microscopy
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Funding
- School of Biological Sciences (SBS)
- Nanyang Technological University (NTU)
- New Initiative Fund FY
- Singapore International Graduate Award (SINGA)
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2-Cys peroxiredoxins (Prxs) are a large family of peroxidases, responsible for antioxidant function and regulation in cell signaling, apoptosis and differentiation. The Escherichia coli alkylhydroperoxide reductase (AhpR) is a prototype of the Prxs-family, and is composed of an NADH-dependent AhpF reductase (57 kDa) and AhpC (21 kDa), catalyzing the reduction of H2O2. We show that the E. coli AhpC (EcAhpC, 187 residues) forms a decameric ring structure under reduced and close to physiological conditions, composed of five catalytic dimers. Single particle analysis of cryo-electron micrographs of C-terminal truncated (EcAhpe(1-172) and EcAhpC(1-182)) and mutated forms of EcAhpC reveals the loss of decamer formation, indicating the importance of the very C-terminus of AhpC in dimer to decamer transition. The crystallographic structures of the truncated EcAhpC(1-172) and EcAhpC(1-182) demonstrate for the first time that, in contrast to the reduced form, the very C-terminus of the oxidized EcAhpC is oriented away from the AhpC dimer interface and away from the catalytic redox-center, reflecting structural rearrangements during redox-modulation and -oligomerization. Furthermore, using an ensemble of different truncated and mutated EcAhpC protein constructs the importance of the very C-terminus in AhpC activity and in AhpC-AhpF assembly has been demonstrated. (C) 2014 Elsevier B.V. All rights reserved.
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