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Bacterial protein HU dictates the morphology of DNA condensates produced by crowding agents and polyamines
Author(s) -
Sarkar Tumpa,
Vitoc Iulia,
Mukerji Ishita,
Hud Nicholas V.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a283-d
Subject(s) - nucleoid , dna , dna condensation , biophysics , macromolecular crowding , microbiology and biotechnology , in vitro , chemistry , premature chromosome condensation , biology , biochemistry , gene , macromolecule , escherichia coli , chromatin , transfection
DNA condensation in vitro by multivalent cations and crowding agents is known to produce nanometer‐scale particles with toroidal, spherical and rod‐like morphologies. Controlling the size and shape of DNA condensates is an integral part of several approaches for the improvement of nonviral gene delivery. Using transmission electron microscopy we demonstrate that the morphology of DNA condensates, formed by polyamines and molecular crowding agent, is shifted completely from toroids to rods if the bacterial protein HU is present during condensation. HU is a nonsequence‐specific DNA binding protein that sharply bends the DNA double helix, but alone does not condense DNA into densely packed particles. Our results illustrate the potential utility of naturally derived proteins for controlling the shape of DNA condensates formed in vitro. HU is an abundant, highly conserved bacterial nucleoid‐associated protein and has been implicated in shaping nucleoid structure. However, the exact role of HU in chromosome compaction is not well understood. Our results regarding how HU governs DNA condensation in vitro suggest a mechanism by which HU could act as an architectural protein in bacterial chromosome compaction and nucleoid organization in vivo. This work was supported by the NIH (GM62873) (NVH), the NSF (MCB 0316625) (IM) and the Patrick and Catherine Weldon Donaghue Medical Research Foundation (IM).