TABLE 1.

Effects of mutations in the spacer region of the overlapping promoters on transcription of lacZ fusions

Region or mutation	Sequencea			Maximum units of β-galactosidase activityb
	BtI (−35)	BtII (−10)	BtI (−10)
Region
Promoter	GCATTTT T	T CATAAGATG AGT	CATATGTT
B. subtilis ςEc	G/TC/AATATT		CATACA-T
B. subtilis ςKc		CATA-------Ta
Mutationd
Wild type (both)				1,100
271 (only BtII)			CGCATGTG	300
272 (only BtI)		CGCAAGACT		5,400
1076 (only BtI)		CATGAGATG		5,200
1077 (both)		CATACAATG		100
1078 (both)		CATAAGATG AC		950
1079 (both)	A	T CATAAGATG		900

^aThe −10 and −35 sequences are in italics, and some neighboring nucleotides are shown. Mutated bases are in boldface type. 

^bSee Fig. 4. 

^cSee reference 33. 

^dFunctional promoters as determined by reverse transcriptase mapping are in parentheses. “both” indicates that BtI and BtII are functional.