Identification and characterization of TRP14, a thioredoxin-related protein of 14 kDa from orange-spotted grouper, Epinephelus coioides

• A TRP14 was firstly cloned from orange-spotted grouper, Epinephelus coioides.
• Ec-TRP14 was up-regulated in the liver of grouper challenged with SGIV.
• The rEc-TRP14 fusion protein possessed the thioredoxin activity.

Thioredoxin (abbreviated as Trx) is an important ubiquitous disulfide reductase, which can protect organisms against various oxidative stresses. In the present study, a thioredoxin-related protein of 14 kDa (named as Ec-TRP14) was identified from the marine fish grouper, Epinephelus coioides by RACE PCR. The full-length cDNA of Ec-TRP14 was comprised of 1066 bp with a 372 bp open reading frame that encodes a putative protein of 123 amino acids. Similar to most TRP14s, Ec-TRP14 contained the conserved motif C-P-D-C. Ec-TRP14 mRNA is predominately expressed in liver, brain and muscle. The expression of Ec-TRP14 was up-regulated in the liver of grouper challenged with SGIV. Ec-TRP14 was recombined and expressed in Escherichia coli BL21 (DE3), and the rEc-Ec-TRP14 fusion protein was demonstrated to possess the antioxidant activity. The grouper spleen (GS) cells were treated with a high concentration of rEc-TRP14 (8.3 μg/ml), which significantly enhanced cells viability under damage caused by viral infection. These results together indicated that Ec-TRP14 could function as an important antioxidant in a physiological context, and might be involved in the responses to viral challenge.