The clamp loader is a component of the DNA polymerase III holoenzyme along with the DNA polymerases that catalyze synthesis of DNA during replication. The function of the clamp loader is to load the β-sliding clamp onto DNA, and the β-sliding clamp in turn binds DNA polymerases to increase the processivity of DNA synthesis. The mechanical clamp loading reaction is powered by ATP binding and hydrolysis, and the clamp loader is a member of the AAA+ family of ATPases. Physical and functional interactions between the DNA polymerase III holoenzyme and SSB are mediated by the χ subunit of the clamp loader. The clamp loader contains seven polypeptides, three copies of the DnaX subunit and one copy each of the δ, δ’, ψ and χ subunits. Here you can see a cryoEM structure of the E. coli clamp loader with closed clamp on primed template DNA (PDB code: 8GJ2)

#molecularart ... #clamp ... #loader ... #complex ... #dna ... #synthesis ... #escherichia ... #cryoem

Structure rendered with @proteinimaging and depicted with @corelphotopaint