title: Molecular profiling and functional insights of rock bream (Oplegnathus fasciatus) thioredoxin reductase 3-like molecule: investigation of its transcriptional modulation in response to live pathogen stress.
abstract: The thioredoxin (Trx) system plays a significant role in cellular antioxidative defense by dismutating the surpluses of reactive oxygen species. Thus, the role of thioredoxin reductase (TrxR) cannot be ignored, owing to its participation in initiating the Trx enzyme cascade. Here, we report the identification and molecular characterization of a teleostean TrxR (RbTrxR-3) ortholog that showed high similarity with the TrxR-3 isoforms of other vertebrates. The complete RbTrxR-3 coding sequence comprised 1800 nucleotides, encoding a 600-amino acid protein with a predicted molecular mass of ~66 kDa. RbTrxR-3 consisted of 16 exons separated by 15 introns and had a total length of 12,658 bp. In silico analysis of the RbTrxR-3 protein sequence revealed that it possesses typical TrxR domain architecture. Moreover, using multiple sequence alignment and pairwise sequence alignment strategies, we showed that RbTrxR-3 has high overall sequence similarity to other teleostean TrxR-3 proteins, including highly conserved active site residues. Phylogenetic reconstruction of RbTrxR-3 affirmed its close evolutionary relationship with fish TrxR-3 orthologs, as indicated by its clustering pattern. RbTrxR-3 transcriptional analysis, performed using quantitative polymerase chain reaction (qPCR), showed that RbTrxR-3 was ubiquitously distributed, with the highest level of mRNA expression in the blood, followed by the gill, and liver. Live bacterial and viral stimuli triggered the modulation of RbTrxR-3 basal transcription in liver tissues that correlated temporally with that of its putative substrate, rock bream thioredoxin1 under the same conditions of pathogenic stress. Finally, resembling the typical function of TrxR protein, purified recombinant RbTrxR-3 showed detectable dose-dependent thiol reductase activity against 5,5'-dithiobis (2-nitrobenzoic) acid. Taken together, these results suggest that RbTrxR-3 plays a role in the host Trx system under conditions of oxidative and pathogenic stress.
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea.
authors.forename: Don Anushka Sandaruwan
authors.initials: DA
authors.lastname: Elvitigala
authors.affiliation: Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea. Electronic address: ilsonwhang@hanmail.net.
authors.forename: Ilson
authors.initials: I
authors.lastname: Whang
authors.affiliation: Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea. Electronic address: jehee@jejunu.ac.kr.
authors.forename: Jehee
authors.initials: J
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D020609:Edwardsiella tarda / Q000276:immunology; D004756:Enterobacteriaceae Infections / Q000201:enzymology / Q000276:immunology / Q000662:veterinary*; D005393:Fish Diseases / Q000097:blood / Q000201:enzymology* / Q000382:microbiology; D029941:Fish Proteins / Q000096:biosynthesis / Q000235:genetics*; D005399:Fishes / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D016415:Sequence Alignment; D013312:Stress, Physiological; D013880:Thioredoxin-Disulfide Reductase / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D029941:Fish Proteins; D013880:Thioredoxin-Disulfide Reductase
keywords: Genomic organization; Rock bream; Thiol reductase activity; Thioredoxin reductase 3; Transcriptional modulation