Abstract
Peroxiredoxins (Prxs) act against hydrogen peroxide (H2O2), organic peroxides, and peroxynitrite. Thermococcus kodakaraensis KOD1, an anaerobic archaeon, contains many antioxidant proteins, including three Prxs (Tk0537, Tk0815, and Tk1055). Only Tk0537 has been found to be induced in response to heat, osmotic, and oxidative stress. Tk0537 was found to belong to a 1-Cys Prx6 subfamily based on sequence analysis and was named 1-Cys TkPrx. Using gel filtration chromatography, electron microscopy, and blue-native polyacrylamide gel electrophoresis, we observed that 1-Cys TkPrx exhibits oligomeric forms with reduced peroxide reductase activity as well as decameric and dodecameric forms that can act as molecular chaperones by protecting both proteins and DNA from oxidative stress. Mutational analysis showed that a cysteine residue at the N-terminus (Cys46) was responsible for the peroxide reductase activity, and cysteine residues at the C-terminus (Cys205 and Cys211) were important for oligomerization. Based on our results, we propose that interconversion between different oligomers is important for regulating the different functions of 1-Cys TkPrx.
Highlights
Thermococcus kodakaraensis KOD1, a model thermophilic organism whose entire genome is sequenced, is a thermophilic anaerobic archaeon belonging to the Thermococcaceae family [1]
The results showed that 1-Cys TkPrx shares a significant degree of identity with 1-Cys Prxs from human (38%), mouse (37%), Arabidopsis (38%), and yeast (36%) (S1 Fig)
We considered that the non-catalytic form of 1-Cys TkPrx might play another role, similar to the dual functions of the 2-Cys Prxs as both peroxidases and molecular chaperones [7]
Summary
Thermococcus kodakaraensis KOD1, a model thermophilic organism whose entire genome is sequenced, is a thermophilic anaerobic archaeon belonging to the Thermococcaceae family [1]. In the typical 2-Cys Prxs, the peroxidatic (CP) and resolving (CR) cysteines are located on different subunits, and the CP attacks an O-O bond of the peroxide (ROOH) substrate to form the product ROH and the sulfenic derivative CP-SOH. This sulfenic derivative forms a disulfide bond (CP-S-S-CR) with the other conserved cysteine residues (CR) [5, 9]. Various activities (peroxidase, molecular chaperone, and DNA binding) of the 1-Cys TkPrx were measured in different redox states. The relationship between the structure and function of 1-Cys TkPrx is discussed
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