Polyamine biosynthesis domain (IPR030374)

Short name: PABS

Domain relationships



The nearly ubiquitous polyamines (putrescine, spermidine and spermine) are polycationic mediators of cell proliferation and differentiation whose functions likely provide both stability and neutralisation for nucleic acids. The following polyamine biosynthetic enzymes are evolutionary related and contain a polyamine biosynthesis (PABS) domain [PMID: 9517003]:

  • Spermidine synthase (EC: (putrescine aminopropyltransferase). It catalyses the last step in the biosynthesis of spermidine from arginine and methionine; the conversion of putrescine to spermidine using decarboxylated S-adenosylmethionine as the cofactor.
  • Spermine synthase (EC: (spermidine aminopropyltransferase). It converts spermidine into spermine using decarboxylated S-adenosylmethionine as the cofactor.
  • Putrescine N-methyltransferase (EC: It catalyses a step in the biosynthesis of nicotine in plants; the methylation of putrescine to N-methylputrescine using S-adenosylmethionine as the cofactor.

The PABS domain consists of two subdomains: an N-terminal subdomain composed of six beta-strands, and a Rossmann-like C-terminal subdomain. The larger C-terminal catalytic core subdomain consists of a seven-stranded beta-sheet flanked by nine alpha helices. This subdomain resembles a topology observed in a number of nucleotide and dinucleotide- binding enzymes, and in S-adenosyl-L-methionine (AdoMet)-dependent methyltransferases (MTases) [PMID: 11731804].

This entry represents the PABS domain that includes the two subdomains.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE profiles