5'-Single-stranded/duplex DNA junctions are loading sites for E. coli UvrD translocase

EMBO J. 2010 Nov 17;29(22):3826-39. doi: 10.1038/emboj.2010.242. Epub 2010 Sep 28.


Escherichia coli UvrD is a 3'-5' superfamily 1A helicase/translocase involved in a variety of DNA metabolic processes. UvrD can function either as a helicase or only as an single-stranded DNA (ssDNA) translocase. The switch between these activities is controlled in vitro by the UvrD oligomeric state; a monomer has ssDNA translocase activity, whereas at least a dimer is needed for helicase activity. Although a 3'-ssDNA partial duplex provides a high-affinity site for a UvrD monomer, here we show that a monomer also binds with specificity to DNA junctions possessing a 5'-ssDNA flanking region and can initiate translocation from this site. Thus, a 5'-ss-duplex DNA junction can serve as a high-affinity loading site for the monomeric UvrD translocase, whereas a 3'-ss-duplex DNA junction inhibits both translocase and helicase activity of the UvrD monomer. Furthermore, the 2B subdomain of UvrD is important for this junction specificity. This highlights a separation of helicase and translocase function for UvrD and suggests that a monomeric UvrD translocase can be loaded at a 5'-ssDNA junction when translocation activity alone is needed.

Publication types

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

MeSH terms

  • 5' Flanking Region
  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Binding Sites
  • DNA Helicases / chemistry
  • DNA Helicases / genetics
  • DNA Helicases / metabolism*
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / metabolism*
  • DNA, Single-Stranded / chemistry
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / metabolism*
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Models, Molecular
  • Mutation
  • Protein Binding
  • Protein Structure, Tertiary
  • Substrate Specificity


  • Bacterial Proteins
  • DNA, Bacterial
  • DNA, Single-Stranded
  • Escherichia coli Proteins
  • pcrA protein, Bacteria
  • UvrD protein, E coli
  • DNA Helicases