A number of bacteria obtain nitrogen by biotin- and ATP-dependent urea degradation system distinct from urease. The two characterized proteins of this system are the enzymes urea carboxylase and allophanate hydrolase, but other, uncharacterized proteins co-occur as genes encoded nearby in multiple organisms. This family includes predicted permeases of the amino acid permease family, likely to transport either urea or a compound from which urea is derived. It is found so far only Actinobacteria, whereas a number of other species with the urea carboxylase have an adjacent ABC transporter operon.
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