Regulation of ornithine decarboxylase from Mycobacterium smegmatis

The activity of ornithine decarboxylase in Mycobacterium smegmatis is regulated by a novel macromolecular inhibitor--a ribonucleic acid. Addition of polyamines to the growth medium enhances the level of this inhibitor, suggesting that the level of this negative modulator changes in response to the intracellular concentration of polyamines. Thus, while other modes of regulation may be operational, the control by polyamines at the transcriptional level leading to the generation of a specific RNA inhibitor seems to be a key element in the regulation of ornithine decarboxylase in mycobacteria.