DNA and RNA-DNA annealing activity associated with the tau subunit of the Escherichia coli DNA polymerase III holoenzyme

Nucleic Acids Res. 1995 Apr 25;23(8):1374-9. doi: 10.1093/nar/23.8.1374.


The DNA polymerase III (pol III)holoenzyme is the 10 subunit replicase of Escherichia coli. The 71 kDa tau subunit, encoded by dnaX, dimerizes the core polymerase (alpha epsilon theta) to form pol III'[(alpha epsilon theta)2 tau 2]. tau is also a single-stranded DNA-dependent ATPase and can substitute for the gamma subunit during initiation complex formation. We show here that tau also possesses a DNA-DNA and RNA-DNA annealing activity that is stimulated by Mg2+, but neither requires ATP nor is inhibited by non-hydrolyzable ATP analogs. This suggests the tau may act to stabilize the primer-template interaction during DNA replication.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Adenosine Triphosphate / analogs & derivatives
  • Adenosine Triphosphate / pharmacology
  • Adenylyl Imidodiphosphate / pharmacology
  • Base Sequence
  • DNA / chemical synthesis
  • DNA / metabolism*
  • DNA Polymerase III / chemistry
  • DNA Polymerase III / metabolism*
  • DNA Replication / physiology
  • Escherichia coli / enzymology*
  • Magnesium Chloride / pharmacology
  • Molecular Sequence Data
  • Nucleic Acid Renaturation / drug effects
  • Polydeoxyribonucleotides / chemical synthesis
  • Polyribonucleotides / chemical synthesis
  • RNA / chemical synthesis
  • RNA / metabolism*


  • Polydeoxyribonucleotides
  • Polyribonucleotides
  • Magnesium Chloride
  • Adenylyl Imidodiphosphate
  • adenosine 5'-O-(3-thiotriphosphate)
  • RNA
  • Adenosine Triphosphate
  • DNA
  • DNA Polymerase III
  • Adenosine Triphosphatases
  • single stranded DNA dependent ATPase