RadA protein from Archaeoglobus fulgidus forms rings, nucleoprotein filaments and catalyses homologous recombination

Nucleic Acids Res. 2001 Nov 15;29(22):4509-17. doi: 10.1093/nar/29.22.4509.


Proteins that catalyse homologous recombination have been identified in all living organisms and are essential for the repair of damaged DNA as well as for the generation of genetic diversity. In bacteria homologous recombination is performed by the RecA protein, whereas in the eukarya a related protein called Rad51 is required to catalyse recombination and repair. More recently, archaeal homologues of RecA/Rad51 (RadA) have been identified and isolated. In this work we have cloned and purified the RadA protein from the hyperthermophilic, sulphate-reducing archaeon Archaeoglobus fulgidus and characterised its in vitro activities. We show that (i) RadA protein forms ring structures in solution and binds single- but not double-stranded DNA to form nucleoprotein filaments, (ii) RadA is a single-stranded DNA-dependent ATPase at elevated temperatures, and (iii) RadA catalyses efficient D-loop formation and strand exchange at temperatures of 60-70 degrees C. Finally, we have used electron microscopy to visualise RadA-mediated joint molecules, the intermediates of homologous recombination. Intriguingly, RadA shares properties of both the bacterial RecA and eukaryotic Rad51 recombinases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphatases / metabolism
  • Adenosine Triphosphate / metabolism
  • Archaeal Proteins / chemistry
  • Archaeal Proteins / genetics
  • Archaeal Proteins / metabolism*
  • Archaeoglobus fulgidus / chemistry
  • DNA / chemistry
  • DNA / metabolism
  • DNA / ultrastructure
  • DNA, Single-Stranded / chemistry
  • DNA, Single-Stranded / metabolism
  • DNA, Single-Stranded / ultrastructure
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Microscopy, Electron
  • Nucleic Acid Conformation
  • Nucleoproteins / chemistry
  • Nucleoproteins / metabolism*
  • Nucleoproteins / ultrastructure
  • Protein Binding
  • Protein Conformation
  • Recombination, Genetic*
  • Temperature


  • Archaeal Proteins
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • Nucleoproteins
  • RadA protein, archaeal
  • Adenosine Diphosphate
  • Adenosine Triphosphate
  • DNA
  • Adenosine Triphosphatases