Structure of the Bacillus subtilis D-aminopeptidase DppA reveals a novel self-compartmentalizing protease

Bacillus subtilis DppA is a binuclear zinc-dependent, D-specific aminopepti dase. The X-ray structure of the enzyme has been determined at 2.4 Angstrom resolution by a three-wavelength MAD experiment. The structure reveals tha t DppA is a new example of a 'self-compartmentalizing protease, a family of proteolytic complexes. Proteasomes are the most extensively studied repres entatives of this family. The DppA enzyme is composed of identical 30 kDa s ubunits organized in a decamer with 52 point-group symmetry. A 20 Angstrom wide channel runs through the complex, giving access to a central chamber h olding the active sites. The structure shows DppA to be a prototype of a ne w family of metalloaminopeptidases characterized by the SXDXEG key sequence .