Caseinolytic protease (ClpP) is an ATP-dependent, highly conserved serine protease
Clp protease (caseinolytic protease; ClpP; Peptidase S14) is a highly conserved serine protease present throughout in bacteria and eukaryota, but seems to be absent in archaea, mollicutes and some fungi. This subfamily only contains bacterial sequences. Clp proteases are involved in a number of cellular processes such as degradation of misfolded proteins, regulation of short-lived proteins and housekeeping removal of dysfunctional proteins. They are also implicated in the control of cell growth, targeting DNA-binding protein from starved cells. ClpP has also been linked to the tight regulation of virulence genes in the pathogens Listeria monocytogenes and Salmonella typhimurium. This enzyme belong to the family of ATP-dependent proteases; the functional Clp protease is comprised of two components: a proteolytic component and one of several regulatory ATPase components, both of which are required for effective levels of protease activity in the presence of ATP, although the proteolytic subunit alone does possess some catalytic activity. Active site consists of the triad Ser, His and Asp; some members have lost all of these active site residues and are therefore inactive, while others may have one or two large insertions. ClpP seems to prefer hydrophobic or non-polar residues at P1 or P1' positions in its substrate. The protease exists as a tetradecamer made up of two heptameric rings stacked back-to-back such that the catalytic triad of each subunit is located at the interface between three monomers, thus making oligomerization essential for function.