N1-aminopropylagmatine, a new polyamine produced as a key intermediate in polyamine biosynthesis of an extreme thermophile, Thermus thermophilus

In the extreme thermophile Thermus thermophilus, a disruption mutant of a gene homologous to speB ( coding for agmatinase = agmatine ureohydrolase) accumulated N-1-aminopropylagmatine (N-8-amidino-1,8-diamino-4-azaoctane, N-8-amidinospermidine), a new compound, whereas all other polyamines produced by the wild-type strain were absent from the cells. Double disruption of speB and speE ( polyamine aminopropyltransferase) resulted in the disappearance of N-1-aminopropylagmatine and the accumulation of agmatine. These results suggested the following. 1) N-1-Aminopropylagmatine is produced from agmatine by the action of an enzyme coded by speE. 2) N-1-Aminopropylagmatine is a metabolic intermediate in the biosynthesis of unique polyamines found in the thermophile. 3) N-1-Aminopropylagmatine is a substrate of the SpeB homolog. They further suggest a new biosynthetic pathway in T. thermophilus, by which polyamines are formed from agmatine via N-1-aminopropylagmatine. To confirm our speculation, we purified the expression product of the speB homolog and confirmed that the enzyme hydrolyzes N-1-aminopropylagmatine to spermidine but does not act on agmatine.