title: The nature of the force-induced conformation transition of dsDNA studied by using single molecule force spectroscopy.
abstract: Single-stranded DNA binding proteins (SSB) interact with single-stranded DNA (ssDNA) specifically. Taking advantage of this character, we have employed Bacillus subtilis SSB protein to investigate the nature of force-induced conformation transition of double-stranded DNA (dsDNA) by using AFM-based single molecule force spectroscopy (SMFS) technique. Our results show that, when a dsDNA is stretched beyond its contour length, the dsDNA is partially melted, producing some ssDNA segments which can be captured by SSB proteins. We have also systematically investigated the effects of stretching length, waiting time, and salt concentration on the conformation transition of dsDNA and SSB-ssDNA interactions, respectively. Furthermore, the effect of proflavine, a DNA intercalator, on the SSB-DNA interactions has been investigated, and the results indicate that the proflavine-saturated dsDNA can be stabilized to the extent that the dsDNA will no longer melt into ssDNA under the mechanical force even up to 150 pN, and no SSB-DNA interactions are detectable.
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, PR China.
authors.forename: Ningning
authors.initials: N
authors.lastname: Liu
authors.forename: Tianjia
authors.initials: T
authors.lastname: Bu
authors.forename: Yu
authors.initials: Y
authors.lastname: Song
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Jinjing
authors.initials: J
authors.lastname: Li
authors.forename: Wenke
authors.initials: W
authors.lastname: Zhang
authors.forename: Jiacong
authors.initials: J
authors.lastname: Shen
authors.forename: Hongbin
authors.initials: H
authors.lastname: Li
mesh_terms: D001696:Biomechanical Phenomena; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018625:Microscopy, Atomic Force / Q000379:methods*; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D044367:Phase Transition; D011370:Proflavine / Q000737:chemistry
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011370:Proflavine