3k70

Crystal structure of the complete initiation complex of RecBCD

spinqualitylabelsall models 3k70, resolution 3.59Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3k70 is a 8 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.59Å Ligands: 5IU, CA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RECB_ECOLI A helicase/nuclease that prepares dsDNA breaks (DSB) for recombinational DNA repair. Binds to DSBs and unwinds DNA via a rapid (>1 kb/second) and highly processive (>30 kb) ATP-dependent bidirectional helicase. Unwinds dsDNA until it encounters a Chi (crossover hotspot instigator, 5'-GCTGGTGG-3') sequence from the 3' direction. Cuts ssDNA a few nucleotides 3' to Chi site, by nicking one strand or switching the strand degraded (depending on the reaction conditions). The properties and activities of the enzyme are changed at Chi. The Chi-altered holoenzyme produces a long 3'-ssDNA overhang which facilitates RecA-binding to the ssDNA for homologous DNA recombination and repair. Holoenzyme degrades any linearized DNA that is unable to undergo homologous recombination (PubMed:4562392, PubMed:4552016, PubMed:123277). In the holoenzyme this subunit contributes ATPase, 3'-5' helicase, exonuclease activity and loads RecA onto ssDNA. The RecBC complex requires the RecD subunit for nuclease activity, but can translocate along ssDNA in both directions. 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 PubMed The molecular mechanism of superfamily 1Balpha helicases remains unclear. We present here the crystal structure of the RecD2 helicase from Deinococcus radiodurans at 2.2-A resolution. The structure reveals the folds of the 1B and 2B domains of RecD that were poorly ordered in the structure of the Escherichia coli RecBCD enzyme complex reported previously. The 2B domain adopts an SH3 fold which, although common in eukaryotes, is extremely rare in bacterial systems. In addition, the D. radiodurans RecD2 structure has aided us in deciphering lower resolution (3.6 A) electron density maps for the E. coli RecBCD enzyme in complex with a long DNA substrate that interacts with the RecD subunit. Taken together, these structures indicated an important role for the 1B domain of RecD, a beta-hairpin that extends from the surface of the 1A domain and interacts with the DNA substrate. On the basis of these structural data, we designed a mutant RecD2 helicase that lacks this pin. The 'pin-less' mutant protein is a fully active ssDNA-dependent ATPase but totally lacks helicase activity. DNA binding to RecD: role of the 1B domain in SF1B helicase activity.,Saikrishnan K, Griffiths SP, Cook N, Court R, Wigley DB EMBO J. 2008 Aug 20;27(16):2222-9. Epub 2008 Jul 31. PMID:18668125 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Exonuclease 3D structures

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