Structure and function of an archaeal topoisomerase VI subunit with homology to the meiotic recombination factor Spo11. |
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Authors: | M D Nichols K DeAngelis J L Keck and J M Berger |
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Institution: | Department of Molecular and Cell Biology, University of California at Berkeley, 229 Stanley Hall-#3206, Berkeley, CA 94720, USA. |
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Abstract: | In all organisms, type II DNA topoisomerases are essential for untangling chromosomal DNA. We have determined the structure of the DNA-binding core of the Methanococcus jannaschii DNA topoisomerase VI A subunit at 2.0 A resolution. The overall structure of this subunit is unique, demonstrating that archaeal type II enzymes are distinct from other type II topoisomerases. However, the core structure contains a pair of domains that are also found in type IA and classic type II topoisomerases. Together, these regions may form the basis of a DNA cleavage mechanism shared among these enzymes. The core A subunit is a dimer that contains a deep groove that spans both protomers. The dimer architecture suggests that DNA is bound in the groove, across the A subunit interface, and that the two monomers separate during DNA transport. The A subunit of topoisomerase VI is homologous to the meiotic recombination factor, Spo11, and this structure can serve as a template for probing Spo11 function in eukaryotes. |
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