Dynamic growth and shrinkage govern the pH dependence of RecA filament stability

PLoS One. 2015 Jan 21;10(1):e0115611. doi: 10.1371/journal.pone.0115611. eCollection 2015.


RecA proteins form a long stable filament on a single-stranded DNA and catalyze strand exchange reaction. The stability of RecA filament changes dramatically with pH, yet its detailed mechanism is not known. Here, using a single molecule assay, we determined the binding and dissociation rates of RecA monomers at the filament ends at various pH. The pH-induced rate changes were moderate but occurred in opposite directions for binding and dissociation, resulting in a substantial increase in filament stability in lower pH. The highly charged residues in C-terminal domain do not contribute to the pH dependent stability. The stability enhancement of RecA filament in low pH may help the cell to cope with acidic stress by fine-tuning of the binding and dissociation rates without losing the highly dynamic nature of the filament required for strand exchange.

Publication types

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

MeSH terms

  • Hydrogen-Ion Concentration
  • Multiprotein Complexes / chemistry*
  • Rec A Recombinases / chemistry*


  • Multiprotein Complexes
  • Rec A Recombinases