3bep
From Proteopedia
Structure of a sliding clamp on DNA
Structural highlights
FunctionDPO3B_ECOLI DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria. This DNA polymerase also exhibits 3' to 5' exonuclease activity. The beta chain is required for initiation of replication once it is clamped onto DNA, it slides freely (bidirectional and ATP-independent) along duplex DNA. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe structure of the E. coli beta clamp polymerase processivity factor has been solved in complex with primed DNA. Interestingly, the clamp directly binds the DNA duplex and also forms a crystal contact with the ssDNA template strand, which binds into the protein-binding pocket of the clamp. We demonstrate that these clamp-DNA interactions function in clamp loading, perhaps by inducing the ring to close around DNA. Clamp binding to template ssDNA may also serve to hold the clamp at a primed site after loading or during switching of multiple factors on the clamp. Remarkably, the DNA is highly tilted as it passes through the beta ring. The pronounced 22 degrees angle of DNA through beta may enable DNA to switch between multiple factors bound to a single clamp simply by alternating from one protomer of the ring to the other. Structure of a sliding clamp on DNA.,Georgescu RE, Kim SS, Yurieva O, Kuriyan J, Kong XP, O'Donnell M Cell. 2008 Jan 11;132(1):43-54. PMID:18191219[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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