Spermine and thermospermine synthases emerged multiple times during eukaryote evolution.

ABSTRACT: The polyamines spermine and thermospermine are differentially distributed throughout eukaryotic phyla. It is unlikely that they were present in the Last Eukaryotic Common Ancestor, thus their biosynthetic enzymes, spermine synthase (SpmSyn) and thermospermine synthase (TspmSyn) emerged during eukaryotic evolution. Herein, we show the different evolutionary mechanisms by which functionally validated SpmSyns and TspmSyns evolved, and their phylogenetic distribution in eukaryotes. Animal lineage SpmSyn was horizontally acquired as a bacterial S-adenosylmethionine decarboxylase-SpmSyn fusion protein before the emergence of the single-celled closest relatives of animals, the Choanoflagellata. SpmSyn has been lost from comb jellies, some sponge species, and was lost from most free-living and par

SUBMITTER: Li B 

PROVIDER: S-EPMC12803844 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature