The MukB-ParC Interaction Affects the Intramolecular,Not Intermolecular,Activities of Topoisomerase IV |
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| Authors: | Ryo Hayama Soon Bahng Mehmet E Karasu Kenneth J Marians |
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| Institution: | From the ‡Physiology, Biophysics, and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, New York 10065 and ;§Molecular Biology Program and ;¶Louis V. Gerstner, Jr. Graduate School of Biomedical Sciences, Memorial Sloan-Kettering Cancer Center, New York, New York 10065 |
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| Abstract: | Proper chromosome organization is accomplished through binding of proteins such as condensins that shape the DNA and by modulation of chromosome topology by the action of topoisomerases. We found that the interaction between MukB, the bacterial condensin, and ParC, a subunit of topoisomerase IV, enhanced relaxation of negatively supercoiled DNA and knotting by topoisomerase IV, which are intramolecular DNA rearrangements but not decatenation of multiply linked DNA dimers, which is an intermolecular DNA rearrangement required for proper segregation of daughter chromosomes. MukB DNA binding and a specific chiral arrangement of the DNA was required for topoisomerase IV stimulation because relaxation of positively supercoiled DNA was unaffected. This effect could be attributed to a more effective topological reconfiguration of the negatively supercoiled compared with positively supercoiled DNA by MukB. These data suggest that the MukB-ParC interaction may play a role in chromosome organization rather than in separation of daughter chromosomes. |
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| Keywords: | Chromosomes DNA Binding Protein DNA Structure DNA Topoisomerase DNA Topology DNA Packaging Condensin |
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