Endopeptidase Clp

Endopeptidase Clp (, endopeptidase Ti, caseinolytic protease, protease Ti, ATP dependent Clp protease, ClpP, Clp protease). This enzyme catalyses the following chemical reaction

Hydrolysis of proteins to small peptides in the presence of ATP and Mg2+. This bacterial enzyme contains subunits of two types, ClpP, with peptidase activity, and the protein ClpA, with AAA+ ATPase activity. ClpP and ClpA are not evolutionarily related. A fully assembled Clp protease complex has a barrel shaped structure in which two stacked heptameric ring of proteolytic subunits (ClpP or ClpQ) are either sandwiched between two rings or single caped by one ring of hexameric ATPase active chaperon subunits (ClpA, ClpC, ClpE, ClpX, ClpY, or others). ClpXP is presented in almost all bacteria while ClpA is found in the Gram negative bacteria, ClpC in Gram Positive bacteria and cyanobacteria. ClpAP, ClpXP and ClpYQ coexist in E. coli while only ClpXP complex in present in humans as mitochondrial enzymes.

The Hsp100 family of eukaryotic heat shock proteins is homologous to the ATPase active chaperon subunits found in the Clp complex; as such the entire group is often referred to as the HSP100/Clp family. The family is usually broken into two parts, one being the ClpA/B family with two ATPase domains, and the other being ClpX and friends with only one such domain. ClpA through E is put into the first group along with Hsp78/104, and ClpX and HSIU is put into the second group. A member of the ClpA/B family termed ClpV is used in the bacterial T6SS.