Nourseothricin (streptothricin) inactivated by a plasmid pIE636 encoded acetyl transferase: nature of the inactivated nourseothricin.

Nourseothricin, a mixture of several streptothricins, is inactivated by an acetyl transferase produced by Escherichia coli containing the plasmid pIE636. Nourseothricin inactivated in the presence of 14C-acetate was purified and submitted to partial hydrolysis. In the hydrolysate besides others a radioactive and ninhydrin-reactive substance moving only slightly towards the cathode was found. It proved to be [14C]-acetyl beta-lysine.