Table 2. Lifetime of β-clamp binding mutants of Pol IIIcore, Pol IV and Pol II.

			Polymerase exchange (%) *
Polymerase	Mutation	Lifetime (s)†	III→IV	IV →III	III + IV
Pol IIIcore	WT	15.7 ± 1.1	70	22	9
	ε (β-)	7.9 ± 1.2	70	26	3
	ε (β+)	40.2 ± 8.7	71	24	6
Pol IV	WT	14.2 ± 1.8	70	22	9
	β groove‡	2.7 ± 0.2	40	60	0
	β rim	14.9 ± 1.7	66	29	5
Polymerase	Mutation	Lifetime (s)†	III→II	II →III	III + II
Pol II	WT	10.4 ± 1.3	71	29	0
	β groove	4.4 ± 0.8	63	37	0

^*Polymerase exchange observed on clamp-DNA showing the exchange from Pol IIIcore to Pol IV or Pol II, Pol IV or Pol II to Pol IIIcore, or co-localization of Pol IIIcore and Pol IV or Pol II.

^†Lifetime on clamp-DNA.

^‡The Pol IV β cleft mutant was measured at high concentrations (90nM) in an attempt to catch co-localization events.