Table 1. Comparison of promoter and promoter-riboswitch properties.

For comparison the approximate promoter strengths and promoter-ribo responses (as measured by GFP fluorescence) are normalized to Phsp60 and Phsp60-ribo, respectively (summarized from Figure 1). For the promoter-ribo constructs, the UNAFold server was used to calculate the predicted RNA secondary structures and calculated free energies for sequences from the transcriptional start through the start codon. The calculated free energy of the riboswitch alone was then subtracted to obtain ΔΔG values as a metric for the secondary structure introduced by the promoter-dependent 5′UTR.

	hsp60	gs	smyc	imyc	MOP	A37	ribo
Promoter strength	1	2.5	2	1	0.1
Maximum response of promoter-ribo	1	1	4	1	0.6	1
Shine-Dalgarno (deduced)	GGAGGAA	AAAGGAG	AAGGAGA	AAGGAG	AGGAG	AAGGAGG	AAGGAGG
# of bases between SD and ATG	10	6	6	7	9	7	7
# of bases between transcriptional start and SD (promoter)	166	32	91	*	37	22
# of bases between transcriptional start and riboswitch (promoter-ribo)	16	33	77	*	59	22
ΔΔG (kcal/mol)	−7.9	−13.8	−30.0	--	−22.2	−10.9
Constant sequence	Y	Y	N	Y	Y	Y

^*The sequence of the 5'UTR is unknown because the transcriptional start site of Pimyc has not been mapped.