title: HU protein induces incoherent DNA persistence length.
abstract: HU is a highly conserved protein that is believed to play an important role in the architecture and dynamic compaction of bacterial DNA. Its ability to control DNA bending is crucial for functions such as transcription and replication. The effects of HU on the DNA structure have been studied so far mainly by single molecule methods that require us to apply stretching forces on the DNA and therefore may perturb the DNA-protein interaction. To overcome this hurdle, we study the effect of HU on the DNA structure without applying external forces by using an improved tethered particle motion method. By combining the results with DNA curvature analysis from atomic force microscopy measurements we find that the DNA consists of two different curvature distributions and the measured persistence length is determined by their interplay. As a result, the effective persistence length adopts a bimodal property that depends primarily on the HU concentration. The results can be explained according to a recently suggested model that distinguishes single protein binding from cooperative protein binding.
authors.affiliation: Physics Department, Bar Ilan University, Ramat-Gan, Israel; Institute for Nanotechnology, Bar Ilan University, Ramat-Gan, Israel.
authors.forename: Guy
authors.initials: G
authors.lastname: Nir
authors.affiliation: Physics Department, Bar Ilan University, Ramat-Gan, Israel; Institute for Nanotechnology, Bar Ilan University, Ramat-Gan, Israel.
authors.forename: Moshe
authors.initials: M
authors.lastname: Lindner
authors.affiliation: Department of Imaging Science and Technology, Delft University of Technology, Delft, The Netherlands.
authors.forename: Heidelinde R C
authors.initials: HRC
authors.lastname: Dietrich
authors.affiliation: Institute for Nanotechnology, Bar Ilan University, Ramat-Gan, Israel.
authors.forename: Olga
authors.initials: O
authors.lastname: Girshevitz
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece.
authors.forename: Constantinos E
authors.initials: CE
authors.lastname: Vorgias
authors.affiliation: Physics Department, Bar Ilan University, Ramat-Gan, Israel; Institute for Nanotechnology, Bar Ilan University, Ramat-Gan, Israel. Electronic address: gariniy@mail.biu.ac.il.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Garini
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism* / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000648:ultrastructure; D001411:Geobacillus stearothermophilus / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D008863:Microspheres
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C040330:histone-like protein HU, bacteria