A self-compartmentalizing protease in Rhodococcus: the 20S proteasome

The 26S proteasome represents a major, energy-dependent and self-compartmen talizing protease system in eukaryotes. The proteolytic core of this comple x, the 20S proteasome, is also ubiquitous in archaea. Although absent from most eubacteria, this multi-subunit protease was recently discovered in Rho dococcus and appears to be confined to actinomycetes. The eubacterial 20S p roteasome represents an attractive complementary system to study proteasome assembly, quaternary structure, and catalytic mechanism. In addition, it i s likely to contribute substantially to our understanding of the role of va rious self-compartmentalizing proteases in bacterial cells.