Improving the thermostability and stress tolerance of an archaeon hyperthermophilic superoxide dismutase by fusion with a unique N-terminal domain

Abstract

The superoxide dismutase from the archaeon Sulfolobus solfataricus (SODSs) is a well-studied hyperthermophilic SOD with crystal structure and possible thermostability factors characterized. Previously, we discovered an N-terminal domain (NTD) in a thermophilic SOD from Geobacillus thermodenitrificans NG80-2 which confers heat resistance on homologous mesophilic SODs. The present study therefore aimed to further improve the thermostability and stress tolerance of SODSs via fusion with this NTD. The recombinant protein, rSODSs, exhibited improved thermophilicity, higher working temperature, improved thermostability, broader pH stability, and enhanced tolerance to inhibitors and organic media than SODSs without any alterations in its oligomerization state. These results suggest that the NTD is an excellent candidate for improving stability of both mesophilic and thermophilic SOD from either bacteria or archaea via simple genetic manipulation. Therefore, this study provides a general, feasible and highly useful strategy for generating extremely thermostable SODs for industrial applications. Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-1854-9) contains supplementary material, which is available to authorized users.

Initial characterization of an iron superoxide dismutase from Thermobifida fusca

“…levisporus [ 60 , 69 ]. Similarly to the results showed here, a SOD from the hyperthermophilic archeon Sulfolobus solfataricus with a relative activity ranging from 65 to 100% has a broad temperature optimum range of 20 to 100 °C [ 70 ]. If an enzyme is to be called thermostable, a high T m , or a long half-life at a temperature above the thermophile boundary for growth (> 55 °C) must be observed [ 40 ].…”

MSD2, an apoplastic Mn-SOD, contributes to root skotomorphogenic growth by modulating ROS distribution in Arabidopsis

“…Peroxynitrite (100 or 200 μM) was added to the protein extract in the dark for 20 min at room temperature [18]. To determine the optimum pH of MSD2 activity, SOD activity was measured in the pH range of 3.0 to 10.0 using 50 mM sodium citrate (pH 3.0-8.0), Tris-HCl (pH 8.0-9.0), or glycine-NaOH (pH 9.0-11.0) buffers [30]. SOD isoenzyme activity was measured according to the manufacturer's instructions in the SOD activity assay kit (Abcam, cat.…”

Enzymatic Antioxidant Signatures in Hyperthermophilic Archaea

“…Most native SODs characterized from hyperthermophilic archaea have been analyzed for industrial applications and, in some cases, site-directed mutagenesis has been used for improving their thermostability as reported for Fe-SOD from A. pyrophilus [109]. Recently, a general and feasible strategy has also been proposed to enhance the thermophilicity and tolerance of both SODs from either bacteria or archaea [110]. The proof of principle description was based on the genetic fusion of SOD from S. solfataricus with the N-terminal domain of SOD from Geobacillus thermodenitrificans.…”