Confers DNA tethering and processivity to DNA polymerases and other proteins. Acts as a clamp, forming a ring around DNA (a reaction catalyzed by the clamp-loading complex) which diffuses in an ATP-independent manner freely and bidirectionally along dsDNA. Initially characterized for its ability to contact the catalytic subunit of DNA polymerase III (Pol III), a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria; Pol III exhibits 3'-5' exonuclease proofreading activity. The beta chain is required for initiation of replication as well as for processivity of DNA replication (By similarity). Interaction with toxin SocB via the hydrophobic cleft blocks DNA replication elongation (PubMed:24239291). Forms a ring-shaped head-to-tail homodimer around DNA which binds and tethers DNA polymerases and other proteins to the DNA. The DNA replisome complex has a single clamp-loading complex (3 tau and 1 each of delta, delta', psi and chi subunits) which binds 3 Pol III cores (1 core on the leading strand and 2 on the lagging strand) each with a beta sliding clamp dimer. Additional proteins in the replisome are other copies of gamma, psi and chi, Ssb, DNA helicase and RNA primase (By similarity). Interacts with DNA replication inhibitor toxin SocB (PubMed:24239291). Forms a discrete locus during DNA replication that moves from one pole to mid-cell before dispersing once DNA has been replicated. Overexpressed tagged toxin SocB colocalizes with these loci but causes their premature collapse (PubMed:24239291). Has 3 promoters, 1 is heat inducible at 42 degrees Celsius (probably under control of sigma-32). Transcription from the other 2 promoters is induced just prior to the onset of DNA replication, at the swarmer-to-stalked-cell transition, lasts through the stalked-cell phase and then decreases in the predivisional cell. Essential, it cannot be deleted. Belongs to the beta sliding clamp family.