TABLE 5.

Dissociation constants for the binding of fork junction and double-stranded promoter fragments to the RNAP holoenzymes containing [104–613, 211Cys-TMR] σ⁷⁰ and full-length σ⁷⁰ [211Cys-TMR] (σ_FL)

The structures of [−38/−7][−38/−12]−35 mut and [−38/−3][−38/−12]−35 mut are shown in Fig. 4; [−38/−12]TG corresponds to the double-stranded fragment of the [−35cons]TG probe shown in Fig. 5A. The K_d values shown are averages obtained from 2 to 3 individual experiments; the error is ±15%.

DNA probe	Kd, σ104–613 RNAP	Kd, σFL RNAP	Kd, σ104–613 RNAP/Kd, σFL RNAP
	nm	nm
[−38/−7][−38/−12]−35 mut	95	2.1	45
[−38/−3][−38/−12]−35 mut	7.6	0.01	760
[−38/−12]TG	57	12	4.7