Table 1.

Plating efficiency of tethered σ⁷⁰ expressed from plasmids in wild-type and mutant strains

		rpoD- straina		rpoB- strainb	rpoC- strainb
Plasmid	Subunit	—IPTG	+IPTG	+IPTG	+IPTG
pTrc99c	None	<10-6	<10-6	<10-6d	<10-6d
pRL663	β′	—	—	—	1
pRL706	β	—	—	1	—
pCL391	σ70	1	1	—	—
pRM314	β′::σ70	<10-6	0.5—1	—	Weak, <10-6 scc
pRM328	β::σ70	<10-6	<10-6	<10-6d	—
pRM317	β′::σ70/32	<10-6	<10-6	—	<10-6d

^aStrain CAG20153 (Supplementary Table 1) in which rpoD transcription is conditionally repressed by TrpR. These strains were tested on plates lacking IAA to prevent rpoD transcription

^brpoC^- strain is RL602 (Supplementary Table 1; functionally rpoC^TS). rpoB strain is RL585 (Supplementary Table 1, functionally rpoB^TS). These strains were plated at 42°C, a nonpermissive temperature for rpoC or rpoB expression

^cWeak growth at 10⁶ cells/mL with ITPG, but not without ITPG; no single colonies (sc) at <10⁶ cells/mL. When struck on IPTG plates, this strain gave growth at 42°C in the heavy part of the streak, but not single colonies. No equivalent growth was observed in plates lacking IPTG

^dNo growth at any cell density with or without IPTG