Identification, Characterization, and Ontogenic Study of Three Novel Zebrafish Cytosolic Sulfotransferases (SULTs‪)‬

In mammals, sulfation as catalyzed by the cytosolic sulfotransfereases (SULTs) is known to be involved in the metabolism and homeostasis of key endogenous compounds such as thyroid/steroid hormones, as well as in the detoxification of xenobioticsincluding drugs. The present study constitutes part of an overall effort in establishing the zebrafish as a model for studying drug sulfation. By searching GenBank database, we have identified sequences encoding three new zebrafish SULTs. These three novel zebrafish SULTs, designated SULT3 ST4, SULT3 ST5 and SULT1 ST9, were cloned, expressed, purified, and characterized. SULT3 ST4 showed strong activity toward endogenous compound such as dehydroepiandrosterine (DHEA), pregnenolone, and 17β-estradiol. SULT3 ST5 showed weaker, but significant, activities toward endogenous compounds such as DHEA and corticosterone, and xenobiotics including mestranol, β-naphthylamine, β-naphthol, and butylated hydroxyl anisole (BHA). SULT1 ST9, on the other hand, appeared to be mostly involved in the metabolism and detoxification of xenobiotics such as β-naphthol, β-naphthylamine, caffeic acid and gallic acid. pH-dependency and kinetic studies were performed using these three enzymes with DHEA, β-naphthol, β-naphthylamine, and 17β-estradiol as substrates. RT-PCR was carried out to investigate the expression of these three novel zebrafish SULTs during various developmental stages from embryogenesis to maturity.