High affinity protein-binding and enzyme-inducing activity of methyltrienolone in Pseudomonas testosteroni

The synthetic androgen methyltrienolone (R 1881) was shown to increase steroid delta 1 dehydrogenase activity when added to cultures of Pseudomonas testosteroni at concentrations of 10(-10)-10(-8)M. Incubation with a soluble extract of P. testosteroni showed that (3H)-R 1881 was bound to a macromolecule with high affinity (Kd 0.6 X 10(-9)M) and low capacity (number of binding sites 120 X 10(-15) mol/mg of protein). The (3H)-R 1881-macromolecule complex was partially destroyed following treatment with protease, was precipitated by addition of ammonium sulfate at 20% of saturation, sedimented at 6.3 S both in 0.01 and 0.4 M KCl solutions, and had an isoelectric point of pH 6.3. The complex was partially bound to DNA-cellulose. Analysis by sucrose gradient centrifugation indicated that neither (3H)-testosterone and (3H)-estradiol-17 beta nor (3H)-corticosterone were bound with high affinity to the (3H)-R 1881-binding macromolecule. It is suggested that the partially characterized R 1881-binding macromolecule, which at least in certain respects resembles androgen receptors described in mammalian cells, is involved in the inductive effect of R 1881 on the delta 1 dehydrogenase activity in P. testosteroni.