Table 1.

Effect of rctA transcription on oriCII plasmid copy number in E. coli

Plasmid* in trans	Glucose/arabinose (0.2%)	Luciferase activity, arbitrary units	Relative copy number of oriCII plasmid pTVC35†
pTVC12 (PBADluc)	Glucose	<0.1	1.0 ± 0.38
	None	47 ± 34	1
	Arabinose	4,830 ± 383	1.0 ± 0.19
pTVC38 (PBADrctA-luc)	Glucose	<0.1	0.29 ± 0.15
	None	129 ± 33	0.44 ± 0.18
	Arabinose	4,787 ± 268	0.68 ± 0.11
pTVC128 (PBADAtcr-luc)	Glucose	<0.1	0.38 ± 0.14
	None	78 ± 47	0.57 ± 0.07
	Arabinose	6,524 ± 474	0.89 ± 0.22

*Cells also had pTVC15 to supply RctB constitutively. Its level was similar in all cases tested (Fig. 5, which is published as supporting information on the PNAS web site).

^†In pTVC35, oriCII fragment is identical to that in pTVC31 except that it has no vector origin (Fig. 1).