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Biochim Biophys Acta. 2014 Dec;1837(12):1932-1943. doi: 10.1016/j.bbabio.2014.08.007.

Key roles of the Escherichia coli AhpC C-terminus in assembly and catalysis of alkylhydroperoxide reductase, an enzyme essential for the alleviation of oxidative stress.

Author information

1
Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551; Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, KTP Building, 8 College Road, Singapore 169857; Center for Bioimaging Sciences, Dept. of Biological Sciences, National University of Singapore, Singapore 119077.
2
Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671.
3
Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551.
4
Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, KTP Building, 8 College Road, Singapore 169857; Center for Bioimaging Sciences, Dept. of Biological Sciences, National University of Singapore, Singapore 119077.
5
Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671; School of Computer Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553; Department of Biological Sciences, National University of Singapore, 8 Medical Drive, Singapore 117597.
6
Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551; Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671. Electronic address: ggrueber@ntu.edu.sg.

Abstract

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 (EcAhpC1 -172 and EcAhpC1 -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 EcAhpC1 -172 and EcAhpC1 -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.

PMID:
25193562
DOI:
10.1016/j.bbabio.2014.08.007
[Indexed for MEDLINE]
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