The Effect of Translationally Controlled Tumor Protein (TCTP) of the Arctic Copepod Calanus glacialis on Protecting Escherichia coli Cells against Oxidative Stress

Abstract

Translationally controlled tumor protein (TCTP) is one of the most abundant proteins in various eukaryotic organisms. TCTPs play important roles in cell physiological processes, being implicated in cancer, cell proliferation, gene regulation, and heat shock response. TCTP is also considered an important factor in the resistance to oxidative stress induced by dithiothreitol or hydrogen peroxide (H2O2). The Arctic calanoid copepods have a variety of antioxidant defense systems to regulate the levels of potentially harmful reactive oxygen species generated by ultraviolet radiation in the Arctic marine ecosystem. However, information on the antioxidant activity of TCTP in the Arctic Calanus glacialis is still scarce. To understand the putative antioxidant function of the Arctic copepod C. glacialis TCTP (Cg-TCTP), its gene was cloned and sequenced. The Cg-TCTP comprised 522 bp and encoded a 174-amino acid putative protein with a calculated molecular weight of ~23 kDa. Recombinant Cg-TCTP (Cg-rTCTP) gene was overexpressed in Escherichia coli (BL21), and Cg-rTCTP-transformed cells were grown in the presence or absence of H2O2. Cg-rTCTP-transformed E. coli showed increased tolerance to high H2O2 concentrations. Therefore, TCTP may be an important antioxidant protein related to C. glacialis tolerance to oxidative stress in the harsh environment of the Arctic Ocean.