The chi psi subunits of DNA polymerase III holoenzyme bind to single-stranded DNA-binding protein (SSB) and facilitate replication of an SSB-coated template. Journal Article uri icon



  • A complex of the chi and psi proteins is required to confer resistance to high levels of glutamate on the DNA polymerase III holoenzyme-catalyzed reaction (Olson, M., Dallmann, H. G., and McHenry, C. (1995) J. Biol. Chem. 270, 29570-29577). We demonstrate that this salt resistance also requires templates to be coated with the Escherichia coli single-stranded DNA-binding protein (SSB). We show that this is the result of a direct chipsi-SSB interaction that is strengthened approximately 1000-fold when SSB is bound to DNA. On model oligonucleotide templates, DNA polymerase III core is inhibited by SSB. We show that the minimal polymerase assembly that will synthesize DNA on SSB-coated templates is polymerase III-tau-psi chi. gamma, the alternative product of the dnaX gene, will not replace tau in this reaction, indicating that tau's unique ability to bind to DNA polymerase III holding chipsi in the same complex is essential. All of our findings are consistent with chipsi strengthening DNA polymerase III holoenzyme interactions with the SSB-coated lagging strand at the replication fork, facilitating complex assembly and elongation.

publication date

  • September 4, 1998

has subject area

has restriction

  • hybrid

Date in CU Experts

  • October 1, 2013 12:09 PM

Full Author List

  • Glover BP; McHenry CS

author count

  • 2

Other Profiles

International Standard Serial Number (ISSN)

  • 0021-9258

Additional Document Info

start page

  • 23476

end page

  • 23484


  • 273


  • 36