Isolation, molecular characterization of cysteine sulfinic acid decarboxylase (CSD) of red sea bream Pagrus major and yellowtail Seriola quinqueradiata and expression analysis of CSD from several marine fish species

Abstract

Cysteine sulfinic acid decarboxylase catalyzes reaction of decarboxylation of cysteine sulfinic acid into hypotaurine. This step is considered as a rate limiting step of taurine biosynthesis in animals. Because of lower CD activity, marine fish has limited ability of de novo taurine synthesis and requires taurine in food. However, if we can develop a method to control CSD activity in marine fish, supplement of taurine to diet of marine fish is not necessary. In order to develop this technique, we have to isolate CSD from marine fish. This study, thereby, is conducted to isolate CSD from red sea bream Pagrus major and yellowtail Seriola quinqueradiata. We also analyze the expression of CSD in red sea bream, yellowtail, Japanese seabass Lateolabrax japonicus, and barfin flounder Verasper moseri. Total RNA was extracted from liver of red sea bream and yellowtail. Primers are designed against sequence of highly conserved region of reported CSD in other animals for RT-PCR. 776bp and 725bp partial CSD sequences were successfully cloned from red sea bream and yellowtail. By 5′ and 3′ RACE methods for cloned partial CSD sequences, total length of CSD (1882bp and 1821bp) from red sea bream and yellowtail was determined. Classification of deduced amino acid sequence revealed that red sea bream and yellowtail CSD showed 88.8% homology similar to Nile tilapia, platyfish, etc. Domain analysis shows that pyridoxine binding region was conserved in CSD from both species.Expression analysis of CSD from red sea bream, Japanese seabass, barfin flounder and yellowtail indicated that CSD is expressed in a variety of tissues but commonly in the liver and pyloric ceca of all species examined. Additionally, strong CSD expression was observed in the heart in all species examined except for Japanese seabass.