Effect of H-NS on the elongation and compaction of single DNA molecules in a nanospace
Author(s)Zhang, Ce; Guttula, Durgarao; Liu, Fan; Malar, Piravi P.; Ng, Siow Yee; Dai, Liang; van Kan, Jeroen A.; van der Maarel, Johan R. C.; Doyle, Patrick S; ... Show more Show less
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The effect of the bacterial heat-stable nucleoid-structuring protein (H-NS) on the conformation of single DNA molecules confined in a nanochannel was investigated with fluorescence microscopy. With increasing concentration of H-NS, the DNA molecules either elongate or contract. The conformational response is related to filamentation of H-NS on DNA through oligomerization and H-NS mediated bridging of distal DNA segments and is controlled by the concentration and ionic composition of the buffer. Confinement in a nanochannel also facilitates compaction of DNA into a condensed form for over-threshold concentrations of H-NS. Divalent ions such as magnesium facilitate but are not required for bridging nor condensation. The time scale of the collapse after exposure to H-NS was determined to be on the order of minutes, which is much shorter than the measured time required for filamentation of around one hour. We found that the effect of H-NS is not only related to its binding properties but also the confinement is of paramount importance. The interplay between confinement, H-NS-mediated attraction, and filamentation controls the conformation and compaction of DNA. This finding might have implications for gene silencing and chromosome organisation, because the cross-sectional dimensions of the channels are comparable to those of the bacterial nucleoid.
DepartmentMassachusetts Institute of Technology. Department of Chemical Engineering
Royal Society of Chemistry
Zhang, Ce et al. “Effect of H-NS on the Elongation and Compaction of Single DNA Molecules in a Nanospace.” Soft Matter 9.40 (2013): 9593. © 2013 Royal Society of Chemistry
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