ATP-dependent serine protease that mediates the selective degradation of mutant and abnormal proteins as well as certain short-lived regulatory proteins. Required for cellular homeostasis and for survival from DNA damage and developmental changes induced by stress. Degrades polypeptides processively to yield small peptide fragments that are 5 to 10 amino acids long. Binds to DNA in a double-stranded, site-specific manner. Hydrolysis of proteins in presence of ATP. Homohexamer. Organized in a ring with a central cavity. By heat shock. Belongs to the peptidase S16 family.