Proceedings of the National Academy of Sciences · 1994 · 145 citations · 30 references
Life SciencesBiochemistryMolecular BiologyDna RepairDna ReplicationEnzymologyDna Double-strand Break RepairDouble-strand Break RepairHelicase FunctionMacromolecular AssemblyProtein StructureReplication In ProkaryotesBranch Migration MechanismsDna Damage InductionDna Holliday JunctionsDouble Holliday JunctionsDouble-stranded Dna StructureHelicase Activity In RepairHolliday Junction Branch MigrationRecombination Reactions
The RuvB protein is induced in Escherichia coli as part of the SOS response to DNA damage. It is required for genetic recombination and the postreplication repair of DNA. In vitro, the RuvB protein promotes the branch migration of Holliday junctions and has a DNA helicase activity in reactions that require ATP hydrolysis. We have used electron microscopy, image analysis, and three-dimensional reconstruction to show that the RuvB protein, in the presence of ATP, forms a dodecamer on double-stranded DNA in which two stacked hexameric rings encircle the DNA and are oriented in opposite directions with D6 symmetry. Although helicases are ubiquitous and essential for many aspects of DNA repair, replication, and transcription, three-dimensional reconstruction of a helicase has not yet been reported, to our knowledge. The structural arrangement that is seen may be common to other helicases, such as the simian virus 40 large tumor antigen.
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Alexander E. Gorbalenya, Eugene V. Koonin, Alexei P. Donchenko et al. · Nucleic Acids Research · 1989 · 1K citations · Full text