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

Olson MW, Dallmann HG, McHenry CS

Published Dec. 8, 1995 in J Biol Chem volume 270 .

Pubmed ID: 7494000

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' 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' was demonstrated by surface plasmon resonance using a Pharmacia BIA-core instrument. In the absence of', chi psi binds to either the gamma or tau DnaX protein with Kd = 2 nM.

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Last modification of this entry: Oct. 6, 2010

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