Polyamines (such as putrescine, spermidine, and spermine) are major cellular components, and have been shown to be involved in many systems related to growth and differentiation. Our studies have been directed at learning how these polyamines are synthesized and regulated, and their physiological function. To this end we have carried out a wide variety of genetic and biochemical studies. We have: (1) established the pathways for the biosynthesis of these amines; (2) isolated the enzymes involved; (3) identified the genes responsible for each of these steps and constructed mutants lacking the encoded enzymes; (4) constructed plasmids that contain these genes, and that permit overproduction of the various enzymes; (5) studied the physiological effects of amine deprivation in vivo on ribosome action and on protein biosynthesis; (6) shown that the genes coding for spermidine synthase (speE) for S- adenosylmethionine decarboxylase (speD) form an operon at 2.7 minutes on the Escherichia coli chromosome. We have sequenced and characterized this operon. (7) We have shown that S- adenosylmethionine decarboxylase is formed as proenzyme which is then processed by a post-transnational cleavage at a lysyl-serine peptide to form two subunits, one of which contains the pyruvoyl group that is found in the mature enzyme and is essential for enzymatic activity. Mutants in which other amino acids are substituted for the lysine result in much slower processing. (8) We have carried out comparable studies in Saccharomyces cerevisiae.