Dissecting elastic heterogeneity along DNA molecules coated partly with Rad51 using concurrent fluorescence microscopy and optical tweezers

  • Van Mameren J
  • Modesti M
  • Kanaar R
 et al. 
  • 52


    Mendeley users who have this article in their library.
  • 38


    Citations of this article.


Nucleoprotein filament formation by recombinases is central to homologous recombination. To follow this process, we used fluorescent human Rad51 recombinase to visualize the interactions with double-stranded DNA (dsDNA). Fluorescence imaging revealed that Rad51 filament formation on dsDNA initiates from multiple nucleation points, resulting in Rad51-dsDNA nucleoprotein filaments interspersed with regions of bare DNA. The elastic properties of such heterogeneously coated DNA molecules were assessed by combining force-extension measurements using optical traps with fluorescence microscopy. This combination of single-molecule techniques allows discrimination of segments within an individual DNA molecule and determination of their elastic properties. The nonfluorescent zones of DNA-Rad51 constructs showed the well-known (over)stretching behavior of bare DNA. In contrast, the fluorescent, Rad51-coated zones did not overstretch and Rad51 remained stably bound in a structure that was ∼50% longer than bare DNA. These results illustrate the power of adding sensitive fluorescence imaging to optical tweezers instrumentation. © 2006 by the Biophysical Society.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Mauro ModestiCentre de Recherche en Cancerologie de Marseille

  • Joost Van Mameren

  • Roland Kanaar

  • Claire Wyman

  • Gijs J L Wuite

  • Erwin J G Peterman

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free