<p>Polyamines such as spermidine and spermine are essential for cellular growth under most conditions, being implicated in a large number of cellular processes including DNA, RNA and protein synthesis. S-adenosylmethionine decarboxylase (AdoMetDC) plays an essential regulatory role in the polyamine biosynthetic pathway by generating the n-propylamine residue required for the synthesis of spermidine and spermine from putrescein [<cite idref="PUB00035745"/>, <cite idref="PUB00035746"/>]. Unlike many amino acid decarboxylases AdoMetDC uses a covalently bound pyruvate residue as a cofactor rather than the more common pyridoxal 5'-phosphate. These proteins can be divided into two main groups which show little sequence similarity either to each other, or to other pyruvoyl-dependent amino acid decarboxylases: class I enzymes found in bacteria and archaea, and class II enzymes found in eukaryotes. In both groups the active enzyme is generated by the post-translational autocatalytic cleavage of a precursor protein. This cleavage generates the pyruvate precursor from an internal serine residue and results in the formation of two non-identical subunits termed alpha and beta which form the active enzyme.</p><p>This entry represents a set of known and predicted AdoMetDC enzymes from proteobacteria. The <taxon tax_id="562">Escherichia coli</taxon> enzyme is a heterooctamer composed of four alpha and four beta chains, and is dependent on mgnesium for activity [<cite idref="PUB00035747"/>].</p> S-adenosylmethionine decarboxylase, bacterial