This family includes known and predicted bacterial and archaeal agmatinase (agmatine ureohydrolase; AUH; SpeB; EC=3.5.3.11), a binuclear manganese metalloenzyme that belongs to the ureohydrolase superfamily. It is a key enzyme in the synthesis of polyamine putrescine; it catalyzes hydrolysis of agmatine to yield urea and putrescine, the precursor for biosynthesis of higher polyamines, spermidine, and spermine. As compared to E. coli where two paths to putrescine exist, via decarboxylation of an amino acid, ornithine or arginine, a single path is found in Bacillus subtilis, where polyamine synthesis starts with agmatine; the speE and speB encode spermidine synthase and agmatinase, respectively. The level of agmatinase synthesis is very low, allowing strict control on the synthesis of putrescine and therefore, of all polyamines, consistent with polyamine levels in the cell. This subfamily belongs to the ureohydrolase superfamily, which includes arginase, agmatinase, proclavaminate amidinohydrolase, and formiminoglutamase.
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