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Molecular motors present in the cell usually utilize chemical energy obtained from ATP hydrolysis to perform mechanical work, which is used to initiate, conduct, and regulate several important processes in a cell. These motors are structurally designed in such a way that they are amazingly efficient, reaching more than 90% efficiency in mechanical work output. Also intriguing is the dynamics of these motors. Whereas bulk experiments give us an ensemble averaged picture, latest developments in single molecule experiments have resulted in high spatial and temporal accuracy, giving us a more precise picture of the cellular events and the structure and dynamics of these motors in particular. I will talk about a molecular motor involved in DNA repair, whose dynamics and interaction kinetics we have studied at the single molecule level with force manipulations with magnetic tweezers. We observe two modes - a diffusive dynamics, and translocation at uniform speeds, with random switching between these two modes. In order to decipher the biological significance of these two modes, we used a single molecule kinetics analysis of the functional relevance of the motor’s structural domains and interactions with DNA, and its interaction kinetics with other partner proteins. |