Molecular Cloning, Expression, and Characterization of Novel Human SULT1C Sulfotransferases That Catalyze the Sulfonation ofN-Hydroxy-2-acetylaminofluorene

Abstract

Upon sulfonation, carcinogenic hydroxyarylamines such as N-hydroxy-2-acetylaminofluorene (N-OH-2AAF) can be further activated to form ultimate carcinogens in vivo. Previous studies have shown that a SULT1C1 sulfotransferase is primarily responsible for the sulfonation of N-OH-2AAF in rat liver. In the present study, two novel human sulfotransferases shown to be members of the SULT1C sulfotransferase subfamily based on sequence analysis have been cloned, expressed, and characterized. Comparisons of the deduced amino acid sequence encoded by the human SULT1C sulfotransferase cDNA 1 reveal 63.7, 61.6, and 85.1% identity to the amino acid sequences of rat SULT1C1 sulfotransferase, mouse SULT1C1 sulfotransferase, and rabbit SULT1C sulfotransferase. In contrast, the deduced amino acid sequence of the human SULT1C sulfotransferase 2 cDNA displays 62.9, 63.1, 63.1, and 62.5% identity to the amino acid sequences of the human SULT1C sulfotransferase 1, rat SULT1C1 sulfotransferase, mouse SULT1C1 sulfotransferase, and rabbit SULT1C sulfotransferase. Recombinant human SULT1C sulfotransferases 1 and 2, expressed in Escherichia coli and purified to near electrophoretic homogeneity, were shown to cross-react with the antiserum against the rat liver SULT1C1 sulfotransferase and exhibited sulfonating activities with N-OH-2AAF as substrate. Tissue-specific expression of these novel human SULT1C sulfotransferases were examined by employing the Northern blotting technique. The results provide a foundation for the investigation into the functional relevance of these new SULT1C sulfotransferases in different human tissues/organs.

Phase II Drug Metabolism

“…SULT1B1 has been found in liver, small intestine, colon, and leukocytes (Wang et al, 1998). Members of SULT1C subfamily were identified in fetal human tissues such as liver (Hehonah et al, 1999) or lung and kidney (Sakakibara et al, 1998) as well as in adult human stomach (Her et al, 1997). The predominant expression of SULT1E1 was found in human liver and jejunum (Riches et al, 2009).…”

Sulfation through the looking glass—recent advances in sulfotransferase research for the curious

“…19,75 considering further: SULTs 1C2 and 1C4 appear to be most highly expressed in fetal tissues, 13 although RNA dot blots indicated the adult stomach and kidney (SULT1C2) and ovary (SULT1C4) may be sites of expression. 18,19 However the function of these enzymes in humans is not clear. The catecholamine sulfotransferase SULT1A3 is expressed at high levels in fetal liver but hepatic expression is essentially absent in the adult-here the gastrointestinal tract is the major site 12 which correlates with the dopaminergic function of the gut, where the majority of dopamine sulfate is produced.…”

“…The human SULT1C2 referred to here was called SULT1C1 or SULT1C sulfotransferase 1 in the original descriptions, 18,19,75 and the human SULT1C4 referred to here was originally called SULT1C2 or SULT1C sulfotransferase. 19,75 considering further: SULTs 1C2 and 1C4 appear to be most highly expressed in fetal tissues, 13 although RNA dot blots indicated the adult stomach and kidney (SULT1C2) and ovary (SULT1C4) may be sites of expression. 18,19 However the function of these enzymes in humans is not clear.…”

Sulfation of ractopamine and salbutamol by the human cytosolic sulfotransferases

“…In humans, 11 SULTs that are categorized into three distinct gene families have been identified and characterized. Seven of the 11 human SULTs that belong to the SULT1 gene family are SULT1A1 and SULT1A2 (both believed to be the general detoxifying enzymes) (19,20), SULT1A3 (dopamine/ catecholamine sulfotransferase) (21), SULT1B1 (thyroid hormone sulfotransferase) (22), SULT1C2 and SULT1C4 (hydroxyarylamine sulfotransferases) (23,24) and SULT1E1 (estrogen sulfotransferase) (25). Three that belong to the SULT2 gene family are SULT2A1 (dehydroepiandrosterone sulfotransferase) (26,27), SULT2B1a (pregnenolone sulfotransferase) (28,29) and SULT2B1b (cholesterol sulfotransferase) (28,29).…”