Characterization of bovine tracheobronchial phenol sulphotransferase cDNA and detection of mRNA regulation by cortisol.

Phenol sulphotransferases esterify both endogenous and foreign hydroxylated aromatic compounds with sulphate. Since these enzymes participate in both hormone and drug metabolism, elucidating their regulation at both the enzymic and molecular levels may provide new understanding in several metabolic pathways. The primary structure of a bovine phenol sulphotransferase has been determined by isolation of the corresponding cDNA. Two partial bovine cDNAs were first isolated by probing a tracheal epithelial cell lambda gt11 cDNA library with a rat phenol sulphotransferase cDNA. These clones provided the sequences of the 5' and 3' ends of the predicted coding region. A contiguous cDNA was subsequently isolated by PCR using 5' and 3' oligonucleotide primers and the cDNA library as the template. The sequence of the resulting approx. 1 kbp cDNA predicted an amino acid sequence that included sequences determined for several tryptic peptides of the purified protein. Antiserum directed to a synthetic N-terminal peptide predicted by the cDNA sequence showed reactivity with the purified enzyme. High-level Trc-promoter-driven expression of the recombinant bovine enzyme was achieved in Escherichia coli. The bovine cDNA was used to determine relative steady-state levels of phenol sulphotransferase transcripts in bovine lung tissues; distal lung parenchymal RNA levels were 6-10-fold greater than those in tracheobronchial epithelium. Using a bronchial epithelial cell culture model, however, cortisol was observed to increase mRNA levels by 5-fold in both a dose- and time-dependent manner; this corresponds to previously reported glucocorticoid stimulation of phenol sulphotransferase activity in this system [Beckmann, Illig and Bartzatt (1994) J. Cell Physiol. 160, 603-610].