Abstract
Animals have varied taurine biosynthesis capability, which was determined by activities of key enzymes including cysteine dioxygenase (CDO) and cysteine sulfinate decarboxylase (CSD). However, whether CDO and CSD are differentially regulated across species remains unexplored. In the present study, we examined the regulations of CDO and CSD in rainbow trout and Japanese flounder, the two fish species with high and low taurine biosynthesis ability respectively. Our results showed that the expression of CDO was lower in rainbow trout but more responsive to cysteine stimulation compared to that in Japanese flounder. On the other hand, both the expression and catalytic efficiency (kcat) of CSD were higher in rainbow trout than those of Japanese flounder. A three-residue substrate recognition motif in rainbow trout CSD with sequence of F126/S146/Y148 was identified to be responsible for high kcat, while that with sequence of F88/N108/F110 in Japanese flounder led to low kcat, as suggested by site-directed mutagenesis studies. In summary, our results determined new aspects of taurine biosynthesis regulation across species.
Highlights
Taurine (2-amino ethanesulfonic acid) is one of the most abundant free amino acids in vertebrates[1]
Taurine biosynthesis is controlled by two key enzymes, cysteine dioxygenase (CDO) and CSD8
CDO and cysteine sulfinate decarboxylase (CSD) have been identified and characterized from mammals to eubacteria[32,35,36,37,38], suggesting the taurine biosynthesis pathway via CDO and CSD is highly conserved during evolution
Summary
Taurine (2-amino ethanesulfonic acid) is one of the most abundant free amino acids in vertebrates[1]. Dietary taurine supplementation stimulated growth on multiple fish species, such as rainbow trout[26], Japanese flounder[27], turbot[21], cobia[28], and yellowtail[29]. Dietary sulfur amino acids stimulated taurine biosynthesis in rainbow trout[19] but not in Japanese flounder[20]. Our previous study suggested that the response of CDO activities to dietary sulfur amino acids was less sensitive in turbot than that in mammals[21]. These results provide clues that the taurine biosynthesis might be differentially regulated among species. The kinetics of recombinant CDO and CSD proteins were investigated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
