DnaX complex of Escherichia coli DNA polymerase III holoenzyme. The chi psi complex functions by increasing the affinity of tau and gamma for delta.delta' to a physiologically relevant range. Journal Article uri icon



  • An artificial operon that contains tandem holC-holD genes was used to overproduce a complex of the chi and psi subunits of the DNA polymerase III holoenzyme. Normally insoluble by itself, psi forms a tight soluble complex with chi. A purification procedure that yields pure, active chi psi complex in 100-mg quantities suitable for biophysical studies is reported. Sedimentation equilibrium studies demonstrate that chi psi is a 1:1 heterodimer. The presence of chi psi dramatically lowers the level of delta.delta' required to reconstitute holoenzyme to levels expected in vivo. That chi psi accomplishes this by binding to gamma or tau and increasing their affinity for delta.delta' was demonstrated by surface plasmon resonance using a Pharmacia BIA-core instrument. In the absence of delta.delta', chi psi binds to either the gamma or tau DnaX protein with Kd = 2 nM.

publication date

  • December 8, 1995

Date in CU Experts

  • October 1, 2013 12:09 PM

Full Author List

  • Olson MW; Dallmann HG; McHenry CS

author count

  • 3

Other Profiles

International Standard Serial Number (ISSN)

  • 0021-9258

Additional Document Info

start page

  • 29570

end page

  • 29577


  • 270


  • 49