Cloning and characterization of selenoprotein thioredoxin reductase gene in Haematococcus pluvialis

Thioredoxin reductase (TR) as a selenoprotein is involved in many cellular processes and mainly serves as a key member of the thioredoxin system, which is a crucial antioxidant system in defense against oxidative stress. We investigated selenoproteins in the important commercial microalgae Haematococcus pluvialis. HpTR1 was identified and its molecular properties were analyzed. The full-length cDNA of HpTR1 consists of 2506 base pairs encoding a putative 535-amino acid product. The conformation of HpTR1 has been characterized via sequence analysis and protein structure modelling. A comprehensive phylogenetic tree of TR1 in animals and algae was constructed, which provided an evolution history of selenoprotein from aquatic to terrestrial environment. The expression pattern of TR1 mRNA and TR activity assay indicate that Selenium is an important regulator of HpTR1 and plays different roles in a dosage dependent manner.