TABLE 3.

Binding of ss- and dsDNA by WT and mutated LTAgs^a

Protein	Binding of ssDNAb				Binding of dsDNAc
	−ATP-γ-S		+ATP-γ-S		−ATP-γ-S		+ATP-γ-S
	Kd,app (nM)	n	Kd,app (nM)	n	Kd,app (nM)	n	Kd,app (nM)	n
WT	180 ± 10	1.8	64 ± 1	1.2	110 ± 10	1.8	95 ± 5	1.8
tK418A mutant	160 ± 20	1.5	100 ± 5	1.5	230 ± 20	1.5	100 ± 10	1.8
tK419A mutant	140 ± 20	1.2	48 ± 5	1.8	200 ± 30	2.0	53 ± 3	2.0
tR498A mutant	80 ± 30	1.6	64 ± 3	1.4	70 ± 7	1.9	60 ± 6	1.8
tD499A mutant	110 ± 20	1.2	100 ± 20	1.4	160 ± 10	1.3	180 ± 40	1.2
tD502A mutant	+		+		−		−
tR540A mutant	67 ± 3	1.8	46 ± 2	2.5	1200 ± 300	1.2	290 ± 20	1.4
cD474A mutant	75 ± 4	1.5	50 ± 1	1.9	290 ± 150	1.2	100 ± 10	1.5
cT527A mutant	100 ± 10	1.0	40 ± 2	1.9	100 ± 10	1.7	50 ± 3	2.3
cN529A mutant	55 ± 3	1.3	57 ± 4	1.4	55 ± 5	1.8	52 ± 4	1.8

^aFor the WT LTAg and each mutant, increasing amounts of LTAg were titrated into a solution containing 50 nM fluorescently labeled ssDNA or dsDNA substrate. The apparent values of K_d (K_d,app) for ss- and dsDNA binding by WT and mutated LTAgs in the presence (+ATP-γ-S) and absence (−ATP-γ-S) of 1 mM ATP-γ-S, measured by rotational fluorescence anisotropy, were calculated by fitting the resultant binding curve to equation 1. Errors in Hill coefficients (n) were typically less than 10%.

^b+, binding detected but data could not be fit to equation 1.

^c−, weak or no binding detected.