Bacillus subtilis tau subunit of DNA polymerase III interacts with bacteriophage SPP1 replicative DNA helicase G40P

Nucleic Acids Res. 2002 Dec 1;30(23):5056-64. doi: 10.1093/nar/gkf650.


Genetic evidence suggests that the Bacillus subtilis dnaX gene only encodes for the tau subunit of both DNA polymerases III (Pol IIIs). The B.subtilis full-length protein and their mutant derivatives tau(373- 563) (lacking the N-terminal, domains I-III or amino acid residues 1-372) and tau(1-372) (lacking the C-terminal region or amino acids 373-563) have been purified. The tau protein forms tetramers, tau(373- 563) forms dimers, whereas tau(1-372), depending on the ionic strength, forms trimers or tetramers in solution. In the absence of single-stranded (ss) DNA and a nucleotide cofactor, tau interacts with the SPP1 hexameric replicative G40P DNA helicase in solution or with G40P-ATP bound to ssDNA, with a 1:1 stoichiometry. G40P(109-442), lacking the N-terminal amino acid residues 1-108, interacts with the C-terminal moiety of tau. The data indicate that the interaction of G40P with the tau subunit of Pol III, is relevant for the loading of the Pol IIIs into the SPP1 G38P-promoted open complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Adenosine Triphosphate / metabolism
  • Bacillus subtilis / enzymology*
  • Bacillus subtilis / genetics
  • Bacillus subtilis / virology
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Bacteriophages / enzymology
  • Bacteriophages / genetics
  • DNA / metabolism
  • DNA Helicases / metabolism*
  • DNA Polymerase III / chemistry
  • DNA Polymerase III / genetics
  • DNA Polymerase III / metabolism*
  • Histidine
  • Mutation
  • Protein Structure, Tertiary
  • Protein Subunits
  • Viral Proteins*
  • Virus Replication


  • Bacterial Proteins
  • DnaX protein, Bacteria
  • Protein Subunits
  • Viral Proteins
  • polyhistidine
  • Histidine
  • Adenosine Triphosphate
  • DNA
  • DNA Polymerase III
  • Adenosine Triphosphatases
  • DNA Helicases
  • G40P helicase protein, Bacteriophage SPP1