3u61
Structure of T4 Bacteriophage Clamp Loader Bound To Closed Clamp, DNA and ATP Analog and ADP
Structural highlights
FunctionLOADL_BPT4 Forms the sliding-clamp-loader together with the small subunit (PubMed:10585481). Functions as an ATPase enzyme (PubMed:16800623, PubMed:18676368). The clamp loader holds the clamp in an open conformation and places it onto the DNA (PubMed:18676368, PubMed:22194570). 4 ATP molecules must bind to the sliding-clamp-loader before the latter can open the sliding clamp (PubMed:18676368). ATP hydrolysis triggers the detachment of the sliding clamp from the sliding-clamp-loader, freeing the sliding clamp to track along DNA (PubMed:18676368, PubMed:22194570).[HAMAP-Rule:MF_04162][1] [2] [3] [4] Publication Abstract from PubMedProcessive chromosomal replication relies on sliding DNA clamps, which are loaded onto DNA by pentameric clamp loader complexes belonging to the AAA+ family of adenosine triphosphatases (ATPases). We present structures for the ATP-bound state of the clamp loader complex from bacteriophage T4, bound to an open clamp and primer-template DNA. The clamp loader traps a spiral conformation of the open clamp so that both the loader and the clamp match the helical symmetry of DNA. One structure reveals that ATP has been hydrolyzed in one subunit and suggests that clamp closure and ejection of the loader involves disruption of the ATP-dependent match in symmetry. The structures explain how synergy among the loader, the clamp, and DNA can trigger ATP hydrolysis and release of the closed clamp on DNA. How a DNA polymerase clamp loader opens a sliding clamp.,Kelch BA, Makino DL, O'Donnell M, Kuriyan J Science. 2011 Dec 23;334(6063):1675-80. PMID:22194570[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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