Unravelling bacterial chromatin organization by H-NS using dual DNA manipulation (In: Nature)
We developed an optical tweezers instrument that can independently handle two DNA molecules. This allows the systematic investigation of (protein-mediated) DNA-DNA interactions. We used this technique to investigate the nucleoid-associated protein H-NS and show that H-NS is dynamically organized between two DNA molecules in register with their helical pitch. Our optical tweezers also allow us to carry out dynamic force spectroscopy and thereby to determine an energy landscape for the H-NS-DNA interaction. Our results explain how the bacterial nucleoid can be effectively compacted and organized, but be dynamic in nature and accessible to DNA tracking motor enzymes.
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Dual architectural roles of HU: formation of flexible hinges and rigid filaments (In: Proc. Natl. Acad. Sci. USA)
Using a combination of scanning force microscopy and magnetic tweezers we demonstrate that the nucleoid-associated protein HU has two binding 'modes'. HU can either introduce flexible bends into DNA or arrange helically around the DNA helix while rigidifying it. Only the first mode of binding induces significant DNA compaction.
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"Magnetisch pincet helpt bij doorgronden DNA: In- en uitpakken"