Sci Rep. 2024 03 30. 14(1): 7566
Teruyuki Kobayashi,
Akihiko Sakamoto,
Tamao Hisano,
Keiko Kashiwagi,
Kazuei Igarashi,
Koichi Takao,
Takeshi Uemura,
Takemitsu Furuchi,
Yoshiaki Sugita,
Toshiyuki Moriya,
Tairo Oshima,
Yusuke Terui.
An extreme thermophilic bacterium, Thermus thermophilus produces more than 20 unusual polyamines, but their biosynthetic pathways, including homospermidine, are not yet fully understood. Two types of homospermidine synthases have been identified in plants and bacteria, which use spermidine and putrescine or two molecules of putrescine as substrates. However, homospermidine synthases with such substrate specificity have not been identified in T. thermophilus. Here we identified a novel agmatine homocoupling enzyme that is involved in homospermidine biosynthesis in T. thermophilus. The reaction mechanism is different from that of a previously described homospermidine synthase, and involves conjugation of two molecules of agmatine, which produces a diamidino derivative of homospermidine (caldomycin) as an immediate precursor of homospermidine. We conclude that there is a homospermidine biosynthetic pathway from agmatine via caldomycin synthase followed by ureohydrolase in T. thermophilus. Furthermore, it is shown that caldomycin is a novel compound existing in nature.