Reverse Gyrase Transiently Unwinds Double-Stranded DNA in an ATP-Dependent Reaction |
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| Authors: | Agneyo Ganguly Yoandris del Toro Duany Dagmar Klostermeier |
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| Institution: | 1. Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, Taipei, Taiwan;2. Institute of Biochemistry, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan;1. Department of General Surgery, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, China;2. Department of Radiology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China;1. Human Molecular Genetics Program, Lurie Children''s Research Center, Chicago, IL, USA;2. Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA;1. Department of Radiation Oncology, Houston Methodist Research Institute, Houston, TX 77030, USA;2. Houston Methodist Neurological Institute, Houston, TX 77030, USA;3. Weill Medical College of Cornell University, New York, USA;1. Department of Radiation Oncology, Houston Methodist Research Institute, Houston, TX 77030, USA;2. Weill Medical College of Cornell University, New York, USA;1. Department of Pharmacology, Post Graduate Institute of Medical Education and Research, Chandigarh, India;2. Department of Experimental Medicine and Biotechnology, Post Graduate Institute of Medical Education and Research, Chandigarh, India;3. Department of Pulmonary Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India;1. School of Food Engineering, Food and Nutrition Department, University of Campinas (UNICAMP), Campinas, SP, 13083-862, Brazil;2. Pontifícia Universidade Católica de Campinas, Centro de Ciências da Vida), Campinas, SP, 13034685, Brazil |
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| Abstract: | Reverse gyrase is a unique DNA topoisomerase that catalyzes the introduction of positive supercoils into DNA in an ATP-dependent reaction. It consists of a helicase domain that functionally cooperates with a topoisomerase domain. Different models for the catalytic mechanism of reverse gyrase that predict a central role of the helicase domain have been put forward. The helicase domain acts as a nucleotide-dependent conformational switch that alternates between open and closed states with different affinities for single- and double-stranded DNA. It has been suggested that the helicase domain can unwind double-stranded regions, but helicase activity has not been demonstrated as yet. Here, we show that the isolated helicase domain and full-length reverse gyrase can transiently unwind double-stranded regions in an ATP-dependent reaction. The latch region of reverse gyrase, an insertion into the helicase domain, is required for DNA supercoiling. Strikingly, the helicase domain lacking the latch cannot unwind DNA, linking unwinding to DNA supercoiling. The unwinding activity may provide and stabilize the single-stranded regions required for strand passage by the topoisomerase domain, either de novo or by expanding already existing unpaired regions that may form at high temperatures. |
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