Sequential eviction of crowded nucleoprotein complexes by the exonuclease RecBCD molecular motor

Proc Natl Acad Sci U S A. 2017 Aug 1;114(31):E6322-E6331. doi: 10.1073/pnas.1701368114. Epub 2017 Jul 17.


In physiological settings, all nucleic acids motor proteins must travel along substrates that are crowded with other proteins. However, the physical basis for how motor proteins behave in these highly crowded environments remains unknown. Here, we use real-time single-molecule imaging to determine how the ATP-dependent translocase RecBCD travels along DNA occupied by tandem arrays of high-affinity DNA binding proteins. We show that RecBCD forces each protein into its nearest adjacent neighbor, causing rapid disruption of the protein-nucleic acid interaction. This mechanism is not the same way that RecBCD disrupts isolated nucleoprotein complexes on otherwise naked DNA. Instead, molecular crowding itself completely alters the mechanism by which RecBCD removes tightly bound protein obstacles from DNA.

Keywords: DNA curtain; RecBCD; molecular crowding; molecular motor; single molecule.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • DNA / chemistry*
  • DNA Replication / physiology*
  • DNA-Binding Proteins / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / metabolism*
  • Exodeoxyribonuclease V / metabolism*
  • Microscopy, Fluorescence
  • Monte Carlo Method
  • Nucleoproteins / metabolism*


  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Nucleoproteins
  • Adenosine Triphosphate
  • DNA
  • Exodeoxyribonuclease V
  • exodeoxyribonuclease V, E coli