Occurrence and induction of spermidine-N¹-acetyltransferase in Escherichia coli

Spermidine acetylase activity was detected in extracts prepared from Escherichia coli and there was a marked increase in activity over the early period of growth. This increase reached a maximum 3 h after inoculation and was followed by an increase in ornithine decarboxylase activity. The acetylase was also able to use spermine as a substrate, but not putrescine. With spermidine and acetyl-CoA as substrate, the product formed was exclusively N¹-acetyl-spermidine. This is the first evidence for the occurrence in bacteria of spermidine-N¹-acetyltransferase, an enzyme which has previously been described in mammalian cells. These results suggest that acetylation of spermidine may be involved in the growth of Escherichia coli and in the regulation of its polyamine content.