The bacterial conjugation protein TrwB resembles ring helicases and F1-ATPase

Nature. 2001 Feb 1;409(6820):637-41. doi: 10.1038/35054586.


The transfer of DNA across membranes and between cells is a central biological process; however, its molecular mechanism remains unknown. In prokaryotes, trans-membrane passage by bacterial conjugation, is the main route for horizontal gene transfer. It is the means for rapid acquisition of new genetic information, including antibiotic resistance by pathogens. Trans-kingdom gene transfer from bacteria to plants or fungi and even bacterial sporulation are special cases of conjugation. An integral membrane DNA-binding protein, called TrwB in the Escherichia coli R388 conjugative system, is essential for the conjugation process. This large multimeric protein is responsible for recruiting the relaxosome DNA-protein complex, and participates in the transfer of a single DNA strand during cell mating. Here we report the three-dimensional structure of a soluble variant of TrwB. The molecule consists of two domains: a nucleotide-binding domain of alpha/beta topology, reminiscent of RecA and DNA ring helicases, and an all-alpha domain. Six equivalent protein monomers associate to form an almost spherical quaternary structure that is strikingly similar to F1-ATPase. A central channel, 20 A in width, traverses the hexamer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Conjugation, Genetic*
  • Crystallography, X-Ray
  • DNA Helicases / chemistry
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / physiology
  • Escherichia coli Proteins*
  • Models, Molecular
  • Protein Conformation
  • Proton-Translocating ATPases / chemistry


  • Bacterial Proteins
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • trwB protein, E coli
  • Proton-Translocating ATPases
  • DNA Helicases

Associated data

  • PDB/1e9r
  • PDB/1e9s