title: Increased bending rigidity of single DNA molecules by H-NS, a temperature and osmolarity sensor.
abstract: Histonelike nucleoid structuring protein (H-NS) is an abundant prokaryotic protein participating in nucleoid structure, gene regulation, and silencing. It plays a key role in cell response to changes in temperature and osmolarity. Force-extension measurements of single, twist-relaxed lambda-DNA-H-NS complexes show that these adopt more extended configurations compared to the naked DNA substrates. Crosslinking indicates that H-NS can decorate DNA molecules at one H-NS dimer per 15-20 bp. These results suggest that H-NS polymerizes along DNA, forming a complex of higher bending rigidity. These effects are not observed above 32 degrees C or at high osmolarity, supporting the hypothesis that a direct H-NS-DNA interaction plays a key role in gene silencing. Thus, we propose that H-NS plays a unique structural role, different from that of HU and IHF, and functions as one of the environmental sensors of the cell.
authors.affiliation: Department of Physics of Complex Systems, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Roee
authors.initials: R
authors.lastname: Amit
authors.forename: Amos B
authors.initials: AB
authors.lastname: Oppenheim
authors.forename: Joel
authors.initials: J
authors.lastname: Stavans
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D010582:Bacteriophage lambda / Q000737:chemistry / Q000235:genetics; D004279:DNA, Viral / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry*; D004548:Elasticity; D046911:Macromolecular Substances; D009994:Osmolar Concentration; D010812:Physical Stimulation / Q000379:methods*; D011108:Polymers / Q000737:chemistry; D012399:Rotation; D015398:Signal Transduction / Q000502:physiology*; D013314:Stress, Mechanical; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D004279:DNA, Viral; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; D046911:Macromolecular Substances; D011108:Polymers