| 1. |
- Fornander, Louise Helena, et al.
(författare)
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Using Nanofluidic Channels to Probe the Dynamics of Rad51-DNA Filaments
- 2014
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 106:2, s. 692A-693A
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Rad51 is a key protein involved in the strand exchange reaction, a reaction where genetic material is transferred between two homologous DNA strands. Strand exchange is initiated by Rad51 forming a helical filament around single-stranded DNA (ssDNA), and the strand exchange is thereafter executed with a homologous double-stranded DNA (dsDNA). The structure of Rad51-DNA filaments, and also the activity of the strand exchange reaction, is dependent on the presence of ATP and dications, where Ca2+ has been shown to promote a higher degree of strand exchange than Mg2+.
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| 2. |
- Frykholm, Karolin, et al.
(författare)
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Probing Physical Properties of a DNA-Protein Complex Using Nanofluidic Channels
- 2014
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 106:2, s. 428A-429A
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Nanofluidic channels have become an important tool to investigate single DNA molecules both from a fundamental polymer physics perspective as well as in e.g. optical mapping techniques. However, less effort has been made to study DNA-protein complexes. A main reason is that the extreme surface-to-volume ratio in the nanochannels causes most proteins to stick to the channel walls. We have recently overcome this problem by coating the channels with a lipid bilayer, thereby eliminating sticking.
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| 3. |
- Frykholm, Karolin, 1977, et al.
(författare)
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Probing Physical Properties of a DNA- Protein Complex Using Nanofluidic Channels
- 2014
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 10:5, s. 884-887
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Tidskriftsartikel (refereegranskat)abstract
- A method to investigate physical properties of a DNA-protein complex in solution is demonstrated. By using tapered nanochannels and lipid passivation the persistence length of a RecA filament formed on double-stranded DNA is determined to 1.15 μm, in agreement with the literature, without attaching protein or DNA to any handles or surfaces.
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| 4. |
- van Mameren, Joost, et al.
(författare)
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Unraveling the structure of DNA during overstretching by using multicolor, single-molecule fluorescence imaging.
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 106:43, s. 18231-6
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Tidskriftsartikel (refereegranskat)abstract
- Single-molecule manipulation studies have revealed that double-stranded DNA undergoes a structural transition when subjected to tension. At forces that depend on the attachment geometry of the DNA (65 pN or 110 pN), it elongates approximately 1.7-fold and its elastic properties change dramatically. The nature of this overstretched DNA has been under debate. In one model, the DNA cooperatively unwinds, while base pairing remains intact. In a competing model, the hydrogen bonds between base pairs break and two single DNA strands are formed, comparable to thermal DNA melting. Here, we resolve the structural basis of DNA overstretching using a combination of fluorescence microscopy, optical tweezers, and microfluidics. In DNA molecules undergoing the transition, we visualize double- and single-stranded segments using specific fluorescent labels. Our data directly demonstrate that overstretching comprises a gradual conversion from double-stranded to single-stranded DNA, irrespective of the attachment geometry. We found that these conversions favorably initiate from nicks or free DNA ends. These discontinuities in the phosphodiester backbone serve as energetically favorable nucleation points for melting. When both DNA strands are intact and no nicks or free ends are present, the overstretching force increases from 65 to 110 pN and melting initiates throughout the molecule, comparable to thermal melting. These results provide unique insights in the thermodynamics of DNA and DNA-protein interactions.
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