ATP-dependent serine protease that mediates the selective degradation of mutant and abnormal proteins as well as certain short-lived regulatory proteins. Degrades polypeptides processively (By similarity). Homohexamer. Organized in a ring with a central cavity (By similarity). This protein undergoes a protein self splicing that involves a post-translational excision of the intervening region (intein) followed by peptide ligation. Belongs to the peptidase S16 family. Archaeal LonB subfamily.