ATP-dependent specificity component of the Clp protease (By similarity). It directs the protease to specific substrates (By similarity). Required for degradation of response regulator CtrA, thus contributing to the G1-to-S transition (PubMed:9755166). Required to degrade DNA replication inhibitor toxin SocB, this function is probably the reason why the protease is essential in this organism (PubMed:24239291). Can perform chaperone functions in the absence of ClpP (By similarity). Component of the ClpX-ClpP complex. Forms a hexameric ring that, in the presence of ATP, binds to fourteen ClpP subunits assembled into a disk-like structure with a central cavity, resembling the structure of eukaryotic proteasomes (By similarity). Interacts with SocA (PubMed:20472802). The N-terminal domain (residues 1-62) is required for interaction with SocA and targeting of SocB for degradation by ClpXP. Essential, it cannot be deleted (PubMed:9755166, PubMed:24239291). When depleted for ClpX cells arrest before the initiation of chromosome replication and are blocked in the cell division process (PubMed:9755166). In depletion experiments ClpX protein starts to decline after about 4 hours, which coincides with cell filamention and a 1000-fold loss of viability by 12 hours; SocB protein accumulates. Deletion of socB permits slower than wild-type growth of the clpX disruption. Belongs to the ClpX chaperone family.