Key roles of the Escherichia coli AhpC C-terminus in assembly and catalysis of alkylhydroperoxide reductase, an enzyme essential for the alleviation of oxidative stressDip, P.V., Kamariah, N., Nartey, W., Beushausen, C., Kostyuchenko, V.A., Ng, T.S., Lok, S.M., Saw, W.G., Eisenhaber, F., Eisenhaber, B., Gruber, G.
(2014) Biochim Biophys Acta
- PubMed: 25193562
- DOI: 10.1016/j.bbabio.2014.08.007
- Structures With Same Primary Citation
- PubMed Abstract:
- The ups and downs in AhpF: Structure, mechanism and ensemble formation of the Alkylhydroperoxide Reductase subunits AhpC and AhpF from Escherichia coli
Dip, P.V., Kamariah, N., Manimekalai, M.S.S., Nartey, W., Balakrishna, A.M., Eisenhaber, F., Eisenhaber, B., Gruber, G.
() To be published --: --
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-f ...
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.
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: email@example.com.