TABLE 2.

Summary of in vitro transcription and glycerol gradient sedimentation results^a

ς32 protein (allele)b	Region affected	Ks (nM)	Maximum yield of transcripts (fmol)	% of core RNAP bindingc:
				Without ς70	With ς70
Wild type
ς32 C-his	None	∼1.5	∼160	>99	∼57
ς32 N-his	None	∼1.7	∼162	>99	∼53
Mutants
Class I
L161P (rpoH182)	3.1	∼3	∼120	>99	∼47
Class II
D179G (rpoH111)	3.1	∼8	∼70	∼94	∼6
R243C (rpoH174)	4.1	∼6	∼108	∼99	∼30
W244R (rpoH161)	4.1	∼7	∼160	∼99	∼28
L245P (rpoH162)	4.1	∼8	∼157	>99	∼4
L270R (rpoH163)	4.2	∼6	≥141	>99	∼22
Class III
F136L (rpoH176)	RpoH box	≥21	≥81	∼33	∼3
L278W (rpoH112)	4.2	≥40	≥157	∼41	∼1
Δ178–201 (rpoH113)	3	NDd	ND	∼28	∼1

^aIn addition to the errors obtained from the experimental procedure in in vitro transcription and in immunoblot assays, there may be additional errors (±20%) from determination of protein concentrations by molar coefficient of extinction. 

^bThe mutants are classed according to their K_ss and glycerol gradient sedimentation data (see Results). 

^cThe estimated percentage of core RNAP-bound ς³² was calculated by densitometry. 

^dND, not determined.